CN116413862A - Wavelength selection device, wavelength selection method and ROADM - Google Patents
Wavelength selection device, wavelength selection method and ROADM Download PDFInfo
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- G—PHYSICS
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
- G02B6/29304—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by diffraction, e.g. grating
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- G02B6/27—Optical coupling means with polarisation selective and adjusting means
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
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- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/27—Optical coupling means with polarisation selective and adjusting means
- G02B6/2753—Optical coupling means with polarisation selective and adjusting means characterised by their function or use, i.e. of the complete device
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
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- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
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- G—PHYSICS
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- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
- G02B6/29379—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device
- G02B6/2938—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
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Abstract
The application provides a wavelength selection device, a wavelength selection method and a ROADM, and belongs to the technical field of optical communication. The wavelength selective device comprises an input port, a diffraction component, a switching engine and an output port, wherein the input port is used for inputting an incident light beam, the reticle spacing at the incidence position of the light beam on the diffraction component is not completely the same, the reticle spacing at the incidence position of the light beam is related to the bandwidth of a channel of the wavelength selective device, the diffraction component is used for dispersing the incident light beam into a plurality of sub-light beams, the wavelengths of the sub-light beams are different, and the switching engine is used for outputting at least one sub-light beam in the plurality of sub-light beams to the output port. By adopting the technical scheme, the reticle pitches at the incidence positions of the light beams of the diffraction components in the wavelength selection device are not identical, so that the bandwidth of the channel of the wavelength selection device can be adjusted on the premise of not changing the complexity of the light path of the wavelength selection device.
Description
Technical Field
The present disclosure relates to the field of optical communications technologies, and in particular, to a wavelength selection device, a wavelength selection method, and a ROADM.
Background
The wavelength selective device is an optical device commonly used in optical communications, e.g. the wavelength selective device is a wavelength selective switch (wavelength selective switch, WSS) or the like. The wavelength selective device includes a diffraction element, which may be a diffraction grating with the same reticle pitch. The diffraction element is used for dispersing an incident light beam into a plurality of light beams with different wavelengths. The bandwidth of the channels of the wavelength selective device may not meet the requirements, such as non-uniformity of the bandwidth of the channels, due to non-uniformity of the dispersion of the diffraction element and chromatic aberration of the spatial optical lens system of the wavelength selective device.
In the related art, a lens or a combination of lenses is typically added to the optical path of the wavelength selective device to adjust the bandwidth of the channel of the wavelength selective device.
The optical path of the wavelength selective device is complicated due to the addition of optical elements in the optical path of the wavelength selective device.
Disclosure of Invention
The application provides a wavelength selection device, a wavelength selection method and a ROADM, which can adjust the bandwidth of a channel of the wavelength selection device without complicating the optical path of the wavelength selection device.
In a first aspect, the present application provides a wavelength selective device comprising an input port, a diffraction element, a switching engine, and an output port; the input port is used for inputting an incident light beam; the pitch of the reticle at the beam incidence location on the diffraction element is not exactly the same, the pitch of the reticle at the beam incidence location being related to the bandwidth of the channel of the wavelength selective device; the diffraction component is used for dispersing the incident light beam into a plurality of sub-light beams, and the wavelength of each sub-light beam is different; the switching engine is used for outputting at least one sub-beam of the plurality of sub-beams to the output port.
According to the scheme, the reticle pitches of the diffraction components in the wavelength selection device at the incidence positions of the light beams are not identical, so that the spot sizes of light spots formed by different light beams on the exchange engine can be adjusted.
In one possible implementation, the wavelength selective device further comprises a polarizing component; the polarization component is used for separating the incident light beam into a first light beam with a first polarization state and a second light beam with a second polarization state, converting the first light beam and the second light beam into the same polarization state, and the first polarization state is orthogonal to the second polarization state; the diffraction element has a first diffraction region in which a pitch of the reticle at a first incident location of the first light beam is not exactly the same, and a second diffraction region in which a pitch of the reticle at a second incident location of the second light beam is not exactly the same, the pitch of the reticle at the first incident location being related to a bandwidth of the channel of the wavelength selective device in the first polarization state, the pitch of the reticle at the second incident location being related to a bandwidth of the channel of the wavelength selective device in the second polarization state; the diffraction element is for dispersing the first light beam into a plurality of first sub-beams and for dispersing the second light beam into a plurality of second sub-beams; the switching engine is used for outputting at least one first sub-beam of the plurality of first sub-beams to the output port and outputting at least one second sub-beam of the plurality of second sub-beams to the output port, the at least one first sub-beam and the at least one second sub-beam have the same wavelength, and the first sub-beam and the second sub-beam with the same wavelength are output from the same output port.
In the solution shown in the present application, when the switching engine is a phase space modulator, the selectivity for the polarization state of the light beam requires that the light beam incident on the phase space modulator is a light beam of a certain polarization state. After the incident light beam is incident to the wavelength selection device, the wavelength selection device divides the incident light beam into two light beams with the same polarization state, the two light beams are respectively incident to a first incident position and a second incident position of the diffraction component, the reticle pitches at the first incident position are not identical, the reticle pitches at the second incident position are not identical, and the bandwidths of the channels of the wavelength selection device under different polarization states can be respectively adjusted, so that the bandwidths of the channels can be more flexibly adjusted.
In one possible implementation, the diffraction element includes a first diffraction grating and a second diffraction grating; the first diffraction region belongs to the first diffraction grating, and the second diffraction region belongs to the second diffraction grating. In this way, two diffraction gratings are used, which is more flexible.
In one possible implementation, the first diffraction region and the second diffraction region are located at adjacent positions within the same plane.
In one possible implementation, the first diffraction region and the second diffraction region are parallel and do not overlap.
In one possible implementation, the first diffraction region includes score lines that are parallel to the score lines included in the second diffraction region.
In one possible implementation, the switching engine is a liquid crystal on silicon (liquid crystal on silicon, LCOS) phase space modulator.
In one possible implementation, the pitch of the score lines at the first incidence location equalizes the bandwidth difference of the channels of the wavelength selective device in the first polarization state, and the pitch of the score lines at the second incidence location equalizes the bandwidth difference of the channels of the wavelength selective device in the second polarization state. In this way, by setting the pitch of the score lines at the first incidence position and the pitch of the score lines at the second incidence position, the bandwidth of the channel can be equalized.
In one possible implementation, the pitch of the scribe lines at the first incident location and the pitch of the scribe lines at the second incident location are such that the channel of the wavelength selective device satisfies the constraint that the first bandwidth difference and the second bandwidth difference are equal or opposite; the first bandwidth difference is the bandwidth difference between the channel with the minimum central wavelength of the wavelength selection device and the channel with the maximum central wavelength of the wavelength selection device in the first polarization state; the second bandwidth difference is the bandwidth difference between the channel with the smallest center wavelength and the channel with the largest center wavelength in the second polarization state. Thus, by setting the pitch of the score lines at the first incidence position and the pitch of the score lines at the second incidence position, the relation of bandwidths of the channels in different polarization states can be adjusted.
In one possible implementation, the pitch of the scribe lines at the first incidence location and the pitch of the scribe lines at the second incidence location are such that each channel of the wavelength selective device satisfies a constraint that the bandwidth difference is equal to a target threshold, the bandwidth difference of each channel being the difference in bandwidths in the first polarization state and the second polarization state. In this way, by setting the pitch of the scribe lines at the first incidence position and the pitch of the scribe lines at the second incidence position, the bandwidth difference of the channel in different polarization states can be made constant.
In a second aspect, the present application provides a method of wavelength selection, the method being applied to a wavelength selective device, the method comprising: the input port outputs an incident light beam to a diffraction element, the pitch of the reticle at the light beam incident position on the diffraction element is not identical, the pitch of the reticle at the light beam incident position is related to the bandwidth of the channel of the wavelength selective device; the diffraction component disperses the incident light beam into a plurality of sub-light beams, each of which has different wavelengths, and outputs the sub-light beams to the exchange engine; the switching engine outputting at least one of the plurality of sub-beams to an output port; the output port outputs the received light beam.
In one possible implementation, the input port inputs an incident light beam to a diffraction element, comprising: the input port outputs an incident light beam to the polarization component; the polarization component separates the incident light beam into a first light beam with a first polarization state and a second light beam with a second polarization state, converts the first light beam and the second light beam into the same polarization state, outputs the same to the diffraction component, and the first polarization state is orthogonal with the second polarization state; the diffraction element has a first diffraction region in which a pitch of the reticle at a first incident location of the first light beam is not exactly the same, and a second diffraction region in which a pitch of the reticle at a second incident location of the second light beam is not exactly the same, the pitch of the reticle at the first incident location being related to a bandwidth of the channel of the wavelength selective device in the first polarization state, the pitch of the reticle at the second incident location being related to a bandwidth of the channel of the wavelength selective device in the second polarization state; the diffraction element disperses the incident light beam into a plurality of sub-beams, including: the diffraction component disperses the first light beam into a plurality of first sub-light beams and outputs the first sub-light beams to the switching engine, and disperses the second light beam into a plurality of second sub-light beams and outputs the second sub-light beams to the switching engine; the switching engine outputting at least one of the plurality of beamlets to an output port, comprising: the switching engine outputs at least one first sub-beam of the plurality of first sub-beams to the output port and outputs at least one second sub-beam of the plurality of second sub-beams to the output port, the at least one first sub-beam and the at least one second sub-beam having the same wavelength, and the first sub-beam and the second sub-beam having the same wavelength are output from the same output port.
In one possible implementation, the diffraction element includes a first diffraction grating and a second diffraction grating; the first diffraction region belongs to the first diffraction grating, and the second diffraction region belongs to the second diffraction grating.
In one possible implementation, the first diffraction region and the second diffraction region are located at adjacent positions within the same plane.
In one possible implementation, the first diffraction region includes score lines that are parallel to the score lines included in the second diffraction region.
In one possible implementation, the pitch of the score lines at the first incidence location equalizes the bandwidth difference of the channels of the wavelength selective device in the first polarization state, and the pitch of the score lines at the second incidence location equalizes the bandwidth difference of the channels of the wavelength selective device in the second polarization state.
In a third aspect, the present application provides a reconfigurable optical add-drop multiplexer (ROADM) comprising at least one wavelength selective device, one or more of the at least one wavelength selective devices being a wavelength selective device of the first aspect or of the possible modes of the first aspect.
In a fourth aspect, the present application provides a method of determining a grating parameter, the method comprising: obtaining grating parameters of a diffraction element in a wavelength selective device, the grating parameters comprising a reticle pitch at a beam incidence position of the diffraction element, the wavelength selective device of the first aspect or in an alternative manner to the first aspect; based on the grating parameters, determining the light spot size and the light spot distance corresponding to each channel of the wavelength selection device, wherein for a target channel, the light spot size corresponding to the target channel is the light spot size of a light beam with the center wavelength of the target channel on a switching engine in the wavelength selection device, and the light spot distance corresponding to the target channel is the distance between light spots of the light beam with the boundary wavelength of the target channel on the switching engine; and adjusting the grating parameters based on the corresponding light spot size and light spot distance of each channel to obtain the target grating parameters meeting the bandwidth constraint condition.
According to the scheme, the light spot size and the light spot distance corresponding to the channels can influence the bandwidth of the channels, so that grating parameters meeting bandwidth constraint conditions can be obtained through feedback based on the light spot size and the light spot distance corresponding to each channel.
In a fifth aspect, the present application provides an apparatus for determining parameters of a grating, the apparatus having the functionality to implement the fourth aspect described above. The apparatus comprises at least one module for implementing the method of determining grating parameters provided in the fourth aspect.
In a sixth aspect, the present application provides a computer device for determining grating parameters, the computer device comprising a processor and a memory; the memory is used for storing computer instructions; the processor is configured to execute the computer instructions to cause a computer device to implement the method for determining a grating parameter provided in the fourth aspect.
In a seventh aspect, the present application provides a computer readable storage medium having stored therein at least one computer instruction that is readable by a processor to cause a computer device to perform the method of determining a grating parameter provided in the fourth aspect above.
In an eighth aspect, the present application provides a computer program product comprising computer instructions stored in a computer readable storage medium. The processor of the computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device performs the method of determining the grating parameter provided in the fourth aspect.
Drawings
FIG. 1 is a schematic diagram of a wavelength selective device provided in an exemplary embodiment of the present application;
FIG. 2 is a schematic illustration of the transmission of a light beam provided by an exemplary embodiment of the present application;
FIG. 3 is a schematic diagram of a diffraction element provided in an exemplary embodiment of the present application;
FIG. 4 is a side view of a diffraction element provided in an exemplary embodiment of the present application;
FIG. 5 is a schematic diagram of a diffraction element provided in an exemplary embodiment of the present application;
FIG. 6 is a schematic diagram of a diffraction element provided in an exemplary embodiment of the present application;
FIG. 7 is a schematic diagram of a wavelength selective device provided in an exemplary embodiment of the present application;
FIG. 8 is a top view of a wavelength selective device provided in one exemplary embodiment of the present application;
FIG. 9 is a schematic diagram of a beam of light imaged on a switching engine provided in accordance with an exemplary embodiment of the present application;
FIG. 10 is a schematic illustration of the dispersion of a light beam on a diffraction element provided in an exemplary embodiment of the present application;
FIG. 11 is a schematic diagram of a beam of light imaged on a switching engine provided in accordance with an exemplary embodiment of the present application;
FIG. 12 is a schematic illustration of filtering provided by an exemplary embodiment of the present application;
FIG. 13 is a schematic diagram of bandwidth versus wavelength provided by an exemplary embodiment of the present application;
FIG. 14 is a schematic diagram of a computer device provided in an exemplary embodiment of the present application;
FIG. 15 is a flow chart of a method of determining grating parameters provided in one exemplary embodiment of the present application;
FIG. 16 is a flow chart of a method of determining grating parameters provided in one exemplary embodiment of the present application;
FIG. 17 is a schematic diagram of bandwidth versus wavelength provided by an exemplary embodiment of the present application;
FIG. 18 is a schematic diagram of bandwidth versus wavelength provided by an exemplary embodiment of the present application;
FIG. 19 is a schematic diagram of bandwidth versus wavelength provided by an exemplary embodiment of the present application;
FIG. 20 is a schematic diagram of bandwidth versus wavelength provided by an exemplary embodiment of the present application;
FIG. 21 is a schematic diagram of bandwidth versus wavelength provided by an exemplary embodiment of the present application;
FIG. 22 is a schematic diagram of bandwidth versus wavelength provided by an exemplary embodiment of the present application;
fig. 23 is a schematic structural view of an apparatus for determining grating parameters according to an exemplary embodiment of the present application.
Description of the drawings
1. An input port; 2. a diffraction member; 3. a switching engine; 4. an output port; 5. a diffraction member; 6. a curved mirror; 7. a cylindrical mirror; 8. a reflecting prism;
21. A first diffraction grating; 22. a second diffraction grating; 23. and a prism.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present application more apparent, the embodiments of the present application will be described in further detail below with reference to the accompanying drawings.
Some term concepts related to the embodiments of the present application are explained below.
The channel is a channel formed by a light beam having a certain wavelength range transmitted in the optical device. Channels may also be referred to as wavelength channels, each channel corresponding to a center wavelength and two boundary wavelengths, the center wavelength being equal to half of the sum of the two boundary wavelengths.
Beam waist, the position where gaussian beams travel absolutely parallel.
The WSS adopts a diffraction grating to carry out free space wave division and wave combination, and a micro-electro-mechanical system (MEMS) or liquid crystal on silicon (liquid crystal on silicon, LCOS) phase space modulator is used for changing the space transmission direction of a light beam, so that the light beam reaches different output ports of the WSS, and the aim of light exchange is fulfilled.
The relevant background referred to in this application is described below.
In optical communications, wavelength selective devices are commonly used, such as WSS, wavelength blockers (wavelength blocker, WB), etc. The wavelength selective device includes a diffraction element, which may be a diffraction grating with the same reticle pitch. The diffraction element is used for dispersing an incident light beam into a plurality of light beams with different wavelengths. The chromatic dispersion of the diffraction element is uneven, and the space optical lens system of the wavelength selection device has chromatic aberration, so that the bandwidth of the channel of the wavelength selection device cannot meet the requirement, such as uneven bandwidth of the channel, and the like. In the related art, a lens or a combination of lenses is typically added to the optical path of the wavelength selective device to adjust the bandwidth of the channel of the wavelength selective device. The addition of optical elements in the optical path of the wavelength selective device can result in a complex optical path of the wavelength selective device.
In this embodiment of the present application, the wavelength selective device includes the diffraction component 2, the reticle pitches at the beam incident positions on the diffraction component 2 are not exactly the same, and the reticle pitches at the beam incident positions are related to the bandwidths of the channels of the wavelength selective device, and all the reticle pitches can be set appropriately to adjust the bandwidths of the wavelength selective device to meet the requirements. It can be seen that only the diffractive part needs to be replaced without adding optical elements in the optical path of the wavelength selective device, so that the optical path of the wavelength selective device is not complicated.
The following describes the structure of the present application in relation to a wavelength selective device.
Referring to the schematic structure of the wavelength selective device shown in fig. 1, the wavelength selective device comprises an input port 1, a diffraction element 2, a switching engine 3 and an output port 4. The input port 1 is connected with an external optical fiber, the pitch of the reticle at the light beam incidence position on the diffraction component 2 is not identical, the pitch of the reticle at the light beam incidence position is related to the bandwidth of the channel of the wavelength selective device, that is, the pitch of the reticle at the light beam incidence position affects the bandwidth of the channel of the wavelength selective device, the switching engine 3 is used for switching the light beam to the output port 4, and the output port 4 is also connected with an external optical fiber for outputting the light beam. The non-identical reticle pitch at the beam incidence location is understood here to be: the light beam incidence position comprises a plurality of scribing lines, and at least two scribing lines in the plurality of scribing lines have different spacing. For example, the plurality of scribe lines includes adjacent first scribe lines and second scribe lines, adjacent third scribe lines and fourth scribe lines, a pitch between the first scribe lines and the second scribe lines is a first scribe line pitch, a pitch between the third scribe lines and the fourth scribe lines is a second scribe line pitch, and at least the first scribe line pitch and the second scribe line pitch in the plurality of scribe line pitches are different.
In the wavelength selective device shown in fig. 1, the beam transmission process is: the incident light beam is input to the wavelength selective device from the input port 1. The incident light beam is transmitted to the diffraction element 2, which diffraction element 2 disperses the incident light beam in a dispersion plane y-z into a plurality of sub-light beams, each of which has a different wavelength. The plurality of sub-beams are transmitted to the switching engine 3, and the switching engine 3 causes the position of the sub-beams in the switching plane x-z to be changed, and outputs at least one sub-beam of the plurality of sub-beams to the output port 4. In the embodiment of the present application, the dispersion plane y-z refers to a plane in which the light beams of the respective wavelengths after the light beams are dispersed by the diffraction element 2, which is also referred to as a wavelength plane, and the switching plane x-z is a plane in which the input port 1 and the output port 4 are located, which is also referred to as a port plane or a switching plane. The dispersion plane y-z and the switching plane x-z are perpendicular to each other.
In the case of a WSS, the multiple sub-beams are all output to the output port 4 for output, and the multiple sub-beams may be output to different output ports 4, or at least two sub-beams may be output to the same output port 4, for example, fig. 2 shows a schematic transmission diagram of the beams, where the wavelength of the incident beam is λ 1 To lambda 3 . Wavelength lambda 1 Is reflected by the switching engine 3, and changes in position in the switching plane x-z, viaThe over-diffraction element 2 is output from the first output port. Wavelength lambda 2 And lambda (lambda) 3 Is reflected by the switching engine 3, changes in position in the switching plane x-z, has a wavelength lambda 2 And lambda (lambda) 3 Is incident on the same position of the diffraction element 2 where the diffraction element 2 emits a light having a wavelength lambda 2 And lambda (lambda) 3 Is combined into one beam, which is output from the second output port.
In the case where the wavelength selection device is WB, the middle sub-beam of the plurality of sub-beams is output to the output port 4, and the other sub-beams are not output from the output port 4. For example, the incident beam has a wavelength lambda 1 To lambda 3 . Wavelength lambda 1 The sub-beams of (a) are reflected by the switching engine 3, and the position of the sub-beams is changed in the switching plane x-z, and the sub-beams are output from the first output port via the diffraction element 2. Wavelength lambda 2 And lambda (lambda) 3 Is reflected by the switching engine 3, changes in position in the switching plane x-z, has a wavelength lambda 2 And lambda (lambda) 3 Is incident on the same position of the diffraction element 2 where the diffraction element 2 emits a light having a wavelength lambda 2 And lambda (lambda) 3 Is combined into one beam which is output to a position other than the output port 4, so that WB will have a wavelength lambda 1 And outputting sub-beams with wavelength lambda 2 And lambda (lambda) 3 Is blocked by a sub-beam of (a).
Illustratively, the input port 1 and the output port 4 may constitute an array of fiber ports comprising at least two ports for connecting optical fibers, respectively, each port for an input beam or an output beam, the ports being referred to as input ports when the ports are for input beams and as output ports when the ports are for output beams.
Illustratively, the switching engine 3 may be a MEMS array, each sub-beam being incident on one MEMS of the MEMS array, such that one MEMS is independently controlling one sub-beam, etc.
Illustratively, the diffraction member 2 includes a diffraction grating and a prism, and the reticle pitches at the beam incidence positions of the diffraction grating are not exactly the same. The prism is attached to the diffraction grating to form a prism grating. The prism can enhance the dispersion capability of the diffraction grating, reduce the dispersion nonlinearity of the diffraction grating, and reduce the influence caused by the conical diffraction effect of the diffraction grating.
The wavelength selective device further comprises, illustratively, a focusing lens located in the optical path between the diffraction element 2 and the switching engine 3 for focusing the sub-beams. In this case, the exchange engine 3 may be located at the focal plane of the focusing lens.
The wavelength selective device may also comprise a mirror, for example, arranged in the light path between the diffraction element 2 and the switching engine 3.
Illustratively, the WSS is generally applied to ROADMs, so that, in order to make the transmission performance of the optical transmission system of the ROADM for light beams with different wavelengths relatively small, the channel bandwidth of the WSS may be balanced, so that the filtering performance of the WSS for light beams with different wavelengths is balanced. In order to equalize the channel bandwidth of the WSS, the reticle pitch at the beam incidence location may be set such that the bandwidth difference of the channels of the WSS satisfies the constraint of equalization.
In the embodiment of the present application, the reason why the bandwidth of the channel can be adjusted by the reticle pitch at the light beam incident position of the diffraction member 2 is as follows: the reticle pitch at the beam incidence position of the diffraction element 2 affects the wavefront phase of the beam, so that the imaging characteristics change, and thus the spot size and position of the beam waist of the beam, which affects the distance of the beam waist to the switching engine 3, which affects the spot size of the beam forming a spot on the switching engine 3, and the spot size of the beam of the channel and p, which affects the bandwidth of the channel, so that the bandwidth of the channel can be adjusted by setting the reticle pitch, p being the size of the channel beam covering the switching engine 3 in the dispersion direction, which is equal to the distance between the spot centers of the beam forming a spot on the switching engine 3 for the beam of the boundary wavelength of the channel. In the embodiment of the application, the reticle pitch at the incidence position of the light beam can be set through simulation. See the description below for specific arrangements.
In a possible implementation, where the diffraction element 2 is a phase space modulator, the phase space modulator is selective for the polarization state of the light beam, requiring that the light beam incident on the phase space modulator be of a certain polarization state. The polarization state of the incident light beam of the wavelength selective device is not uniform, and the incident light beam is converted into the same polarization state by the polarization component 5 before the incident light beam enters the phase modulator. In this case, the wavelength selective device further comprises a polarization component 5, the polarization component 5 being configured to split the incident light beam into a first light beam of a first polarization state and a second light beam of a second polarization state, the first polarization state and the second polarization state being perpendicular. For example, the first and second polarization states may be S and P polarization states, respectively, and the first and second polarization states may be other orthogonal polarization states.
When the wavelength selective device comprises a polarizing component 5, the beam transmission process is as follows:
the incident light beam is input to the wavelength selective device from the input port 1. The incident light beam is transmitted to the polarization component 5, and the polarization component 5 splits the incident light beam into a first light beam of a first polarization state and a second light beam of a second polarization state, the first and second light beams having the same wavelength, e.g., the incident light beam having a wavelength lambda 1 To lambda n The wavelength of the first light beam is lambda 1 To lambda n The wavelength of the second light beam is lambda 1 To lambda n N is an integer greater than 1. The polarization assembly 5 converts the first and second light beams into the same polarization state. The same polarization state to which the first light beam and the second light beam are converted may be an S polarization state or the like, or may be other polarization states.
The first light beam is transmitted to the diffraction element 2 at a first incidence position, the second light beam is transmitted to the diffraction element 2 at a second incidence position, the first light beam is dispersed by the diffraction element 2 into a plurality of first sub-light beams, each of which has a different wavelength, and the second light beam is dispersed by the diffraction element 2 into a plurality of second sub-light beams, each of which has a different wavelength.
The plurality of first sub-beams and the plurality of second sub-beams are transmitted to the switching engine 3, the switching engine 3 outputs at least one first sub-beam of the plurality of first sub-beams to the output port 4 and outputs at least one second sub-beam of the plurality of second sub-beams to the output port 4, the at least one first sub-beam and the at least one second sub-beam have the same wavelength, and the first sub-beam and the second sub-beam of the same wavelength are output from the same port. For example, in the case where the wavelength selective device is a WSS, the first sub-beam and the second sub-beam obtained by dispersion are both output from the output port 4, and the first sub-beam and the second sub-beam having the same wavelength are combined into one beam before being output to the output port 4, and the beams having different wavelengths may be output from the same output port 4 or may be output from different output ports 4.
Illustratively, the diffraction member 2 has a first diffraction region and a second diffraction region, and fig. 3 shows a schematic structural view of the diffraction member 2, and the diffraction member 2 has the first diffraction region and the second diffraction region. The first diffraction region is used for dispersing an incident first light beam into a plurality of first sub-light beams, the wavelength of each first sub-light beam is different, and the second diffraction region is used for dispersing an incident second light beam into a plurality of second sub-light beams, and the wavelength of each second sub-light beam is different. The pitch of the reticle at the incidence position of the first light beam in the first diffraction region (referred to as the first incidence position) is not identical, and the pitch of the reticle at the incidence position of the second light beam in the second diffraction region (referred to as the second incidence position) is not identical. The pitch of the score lines at the first location of incidence is related to the bandwidth of the channels of the wavelength selective device in the first polarization state and the pitch of the score lines at the second location of incidence is related to the bandwidth of the channels of the wavelength selective device in the second polarization state. In this way, the pitch of the score lines at the first incidence position can be set such that the bandwidth of the channels of the wavelength selective device in the first polarization state meets the requirements, and the pitch of the score lines at the second incidence position can be set such that the bandwidth of the channels of the wavelength selective device in the second polarization state meets the requirements.
The pitch of the score lines at the first incidence position is not exactly the same, which can be understood as: the first incident position comprises a plurality of scribing lines, and at least two scribing line spaces in the plurality of scribing lines are different. For example, the plurality of scribe lines includes adjacent first scribe lines and second scribe lines, adjacent third scribe lines and fourth scribe lines, a pitch between the first scribe lines and the second scribe lines is a first scribe line pitch, a pitch between the third scribe lines and the fourth scribe lines is a second scribe line pitch, and at least the first scribe line pitch and the second scribe line pitch in the plurality of scribe line pitches are different. Similarly, the pitch of the score lines at the second incidence position is not exactly the same may be understood as: the second incidence position comprises a plurality of scribing lines, and at least two scribing line spaces formed by the plurality of scribing lines are different.
Note that the pitch of the score lines at the first incidence position and the pitch of the score lines at the second incidence position can be obtained by simulation. Illustratively, the reticle pitch is obtained by simulation based on the channel bandwidth requirements of the wavelength selective device to which the diffraction element 2 is applied.
In addition, for ease of understanding, a side view of the first and second diffraction regions is shown in fig. 4.
Illustratively, the diffraction element 2 comprises two diffraction gratings, both being reflective diffraction gratings. The two diffraction gratings are a first diffraction grating 21 and a second diffraction grating 22, the first diffraction region belonging to the first diffraction grating 21 and the second diffraction region belonging to the second diffraction grating 22. In this way, the first diffraction grating 21 is used for performing dispersion processing on the first light beam, the second diffraction grating 22 is used for performing dispersion processing on the second light beam, and the two diffraction gratings can be provided with a reticle spacing, a substrate material type and a distance between the two diffraction gratings, so that the degree of freedom of design is increased, and the diffraction component 2 is easier to design so that the wavelength selection device has a requirement on the channel bandwidth.
Illustratively, the base materials of the first diffraction grating 21 and the second diffraction grating 22 may be the same or different, which is not limited in the embodiment of the present application.
Illustratively, the first diffraction region may include a scribe line and the second diffraction region may include a scribe line that are parallel. In this way, it is easier to machine the diffraction member 2.
For example, the first diffraction region and the second diffraction region may be parallel in positional relationship, but do not overlap so that the first light beam and the second light beam are incident separately, and may overlap in some cases, except that the light beam incidence is not blocked. In the case where the first diffraction region belongs to the first diffraction grating 21 and the second diffraction region belongs to the second diffraction grating 22, the first diffraction grating 21 and the second diffraction grating 22 may be parallel. In the diffraction member 2 shown in fig. 5, the first diffraction grating 21 and the second diffraction grating 22 are parallel.
Illustratively, the first diffraction region and the second diffraction region are located at adjacent positions or non-adjacent positions in the same plane, which is not limited in the embodiments of the present application. In the case where the first diffraction region belongs to the first diffraction grating 21 and the second diffraction region belongs to the second diffraction grating 22, the first diffraction grating 21 and the second diffraction grating 22 may be disposed at adjacent positions or non-adjacent positions. In fig. 3, the first diffraction grating 21 and the second diffraction grating 22 are disposed at adjacent positions, and in fig. 6, the first diffraction grating 21 and the second diffraction grating 22 are disposed at non-adjacent positions.
Illustratively, the diffraction element 2 further includes a prism 23, where the prisms 23 are attached to the first diffraction grating 21 and the second diffraction grating 22 to form a prism. The prism 23 can enhance the dispersive power of the first diffraction grating 21 and the second diffraction grating 22, reduce the dispersion nonlinearity of the first diffraction grating 21 and the second diffraction grating 22, and reduce the influence by the conical diffraction effect of the first diffraction grating 21 and the second diffraction grating 22.
The wavelength selective device also comprises, for example, a curved mirror 6, a cylindrical mirror 7, etc. The curved mirror 6 is used to collimate and converge the light beam in the dispersion plane y-z. The cylindrical mirror 7 is used for collimating and converging the light beam in the switching plane x-z. The polarizing component 5 is located on the optical path between the input port 1 and the curved mirror 6, the curved mirror 6 is located on the optical path between the polarizing component 5 and the cylindrical mirror 7, the diffraction element 2 is located on the optical path between the cylindrical mirror 7 and the curved mirror 6, and the cylindrical mirror 7 is located on the optical path between the switching engine 3 and the curved mirror 6.
Illustratively, the switching engine 3 is an LCOS phase space modulator. The LCOS phase space modulator includes a plurality of pixels for applying voltages to the pixels of the beam-covered region, and changing the phase of the light beam by changing the refractive index of the liquid crystal material, so that the position of the light beam in the switching plane x-z changes. Optionally, the wavelength selection device further includes a reflecting prism 8, the curved mirror 6 reflects the first sub-beam and the second sub-beam to the reflecting prism 8, and the reflecting prism 8 reflects the received sub-beams with different wavelengths to different pixel areas of the LCOS phase space modulator.
Illustratively, the polarizing assembly 5 includes a shaping component for collimating and shaping the light beam and a polarizing component. The polarization component is used for separating an input light beam into two light beams with orthogonal polarization states, and converting the two light beams with orthogonal polarization states into two light beams with the same polarization state.
Illustratively, in the case where the wavelength selective device further includes a curved mirror 6 and a cylindrical mirror 7, the light beam is transmitted in the wavelength selective device as follows:
as shown in fig. 7, after an incident light beam is incident from the input port 1, the shaping member performs collimation and shaping processing on the incident light beam. The polarization component splits the collimated and shaped beam into two beams of orthogonal polarization and converts into two output beams of the same polarization, which are referred to as a first beam L1 and a second beam L2. The first and second light beams are incident on curved mirror 6, and curved mirror 6 has optical power in dispersion plane y-z, which is equal to the difference between the convergence of image Fang Guangshu and the convergence of the object beam, which characterizes the ability of the optical system to deflect the light, acts to collimate and converge first and second light beams L1 and L2 in dispersion plane y-z, and reflects first and second light beams L1 and L2 onto cylindrical mirror 7.
The cylindrical mirror 7 has optical power in the switching plane x-z, acts to collimate and converge the first light beam L1 and the second light beam L2 in the switching plane x-z, and transmits the first light beam L1 and the second light beam L2 to the first diffraction region and the second diffraction region of the diffraction element 2, respectively. The first diffraction region of the diffraction element 2 disperses the first light beam L1 to obtain a plurality of first sub-light beams. The second light beam L2 is dispersed by the second diffraction region of the diffraction element 2, and a plurality of second sub-light beams are obtained. The plurality of first sub-beams and the plurality of second sub-beams sequentially pass through the cylindrical mirror 7 and the curved mirror 6, the curved mirror 6 converts the plurality of first sub-beams into parallel light to be incident on the LCOS phase space modulator, and the curved mirror 6 converts the plurality of second sub-beams into parallel light to be incident on the LCOS phase space modulator. The sub-beams of the same wavelength in the first sub-beam and the second sub-beam are incident at the same location of the LCOS phase space modulator.
The LCOS phase space modulator applies voltages to the pixel points of the coverage area of the first sub-beam and the coverage area of the second sub-beam, and changes the phases of the first sub-beam and the second sub-beam by changing the refractive index of the liquid crystal material, so that the positions of the first sub-beam and the second sub-beam in the switching plane x-z are changed, and the first sub-beam and the second sub-beam after the phase change of the LCOS phase space modulator return to the output port 4 along the curved mirror 6, the cylindrical mirror 7, the diffraction component 2 and the polarization component 5 for output. For example, an incident light beam is input from the first input port, the wavelength of the incident light beam includes λ 1 To lambda 5 ，λ 1 To lambda 3 Is output from the first output port lambda 4 And lambda (lambda) 5 Is output from the second output port. The voltage applied to the pixel of the LCOS phase space modulator may be applied to each pixel of the LCOS phase space modulator, but the voltage applied to each pixel may be different, or the voltage may be applied to only the pixel at the beam incident position.
Here, the path of the first sub-beam of the first wavelength returning to the output port 4 is a first path, the path of the second sub-beam of the first wavelength incident on the LCOS phase space modulator is a second path, and the projection of the first path and the second path in the dispersion plane y-z is the same. The path of the second sub-beam of the first wavelength, which is returned to the output port 4, is a third path, the path of the first sub-beam of the first wavelength, which is incident to the LCOS phase space modulator, is a fourth path, and the projection of the third path and the fourth path in the dispersion plane y-z is the same.
Note that fig. 7 shows a schematic diagram of transmission of only one beam. For a better understanding of the structure of the wavelength selective device, fig. 8 shows a top view of the wavelength selective device. In fig. 8, in the dispersion plane y-z, the first sub-beams obtained by the dispersion of the first light beam L1 coincide, and the second sub-beams obtained by the dispersion of the second light beam L2 coincide. In fig. 8, the input port 1 and the output port 4 overlap in plan view, and may be regarded as an array of fiber ports.
For example, the wavelength selective device may be generally applied to a ROADM, so that, in order to make the transmission performance of an optical transmission system of the ROADM for light beams with different wavelengths relatively small, the channel bandwidth of the wavelength selective device may be balanced, so that the filtering performance of the wavelength selective device for light beams with different wavelengths is balanced. In order to equalize the channel bandwidths of the wavelength selective devices, the reticle pitches of the first diffraction regions may be set such that the bandwidth differences of the channels of the wavelength selective devices in the first polarization state satisfy the equalization constraint conditions, and the reticle pitches of the second diffraction regions may be set such that the bandwidth differences of the channels of the wavelength selective devices in the second polarization state satisfy the equalization constraint conditions.
Illustratively, in a dense wavelength division multiplexing system, the wavelength selective devices in the system have different responses to light beams with different wavelengths, and the bandwidths of the channels of the wavelength selective devices can be designed according to the requirements of the system. For example, in some cases, the tendency of the bandwidth to change with the channel may be adjusted, and the channel is defined based on the wavelength of the light beam, so it may be understood that the tendency of the bandwidth to change with the wavelength is adjusted, for example, the larger the center wavelength of the channel, the larger the bandwidth of the channel, or the smaller the center wavelength of the channel, the larger the bandwidth of the channel. In the embodiment of the application, by setting the reticle pitches of the first diffraction region and the second diffraction region, the channel of the wavelength selection device can meet the constraint condition that the first bandwidth difference value and the second bandwidth difference value are equal. For another example, some optical devices (such as transmission fibers) in the optical transmission system of the ROADM have polarization correlation, and the polarization state change in the light beam transmission process can affect the transmission performance of the optical transmission system, so that the bandwidth distribution adjustment under different polarization states of the same channel is beneficial to balancing the influence of different polarization states on the transmission performance of the optical transmission system. In the embodiment of the application, by setting the reticle pitches of the first diffraction region and the second diffraction region, the channel of the wavelength selection device can meet the constraint condition that the first bandwidth difference value and the second bandwidth difference value are opposite to each other. The first bandwidth difference is the bandwidth difference between the channel with the minimum center wavelength of the wavelength selection device and the channel with the maximum center wavelength of the wavelength selection device in the first polarization state, and the second bandwidth difference is the bandwidth difference between the channel with the minimum center wavelength and the channel with the maximum center wavelength in the second polarization state.
Under the constraint that the first bandwidth difference value and the second bandwidth difference value are equal, the variation trend of the bandwidth of the channel along with the wavelength in the first polarization state and the second polarization state is consistent, and the wavelength distribution adjustment of the bandwidth of the channel independent of the polarization state can be realized. Under the constraint that the first bandwidth difference value and the second bandwidth difference value are opposite numbers, the change trend of the bandwidth of the channel along with the wavelength is opposite in the first polarization state and the second polarization state, and the adjustment of the bandwidth of the channel along with the wavelength distribution in different polarization states can be realized. The minimum center wavelength is equal to an average of a minimum wavelength and a sub-minimum wavelength of the light beam incident on the wavelength selective device, and the maximum center wavelength is equal to an average of a maximum wavelength and a sub-maximum wavelength of the light beam incident on the wavelength selective device.
Illustratively, in some cases, the bandwidth difference between different polarization states is required to be constant for channels of arbitrary wavelength. In order to achieve a constant bandwidth difference requirement between different polarization states for channels of any wavelength, the reticle spacings of the first and second diffraction regions may be set such that each channel of the wavelength selective device satisfies the constraint that the bandwidth difference in the first and second polarization states is equal to the target threshold. The target threshold may be preset, such as 0.5GHz, etc.
It should be noted that, when the incident light beam passes through the polarization component 5, the incident light beam is first split into a first light beam with a first polarization state and a second light beam with a second polarization state, and then the first light beam and the second light beam are converted into the same polarization state, where the first light beam and the second light beam are incident on the switching engine 3, and may be considered that the light beams from two orthogonal polarization states are incident on the switching engine 3, and the channel of the wavelength selective device may have bandwidths in the two orthogonal polarization states.
The center position of the spot on the switching engine 3 is unchanged for the first sub-beam compared to the use of diffraction elements having equal reticle pitches. The second sub-beam does not change the central position of the spot on the switching engine 3.
Illustratively, for a better understanding of the embodiments of the present application, parameters affecting the bandwidth of the channel of the wavelength selective device are described below, and here, a target beam is illustrated as an example, where the target beam may be a first sub-beam or a second sub-beam.
Fig. 9 shows the imaging of the target beam at the switching engine 3. For convenience of understanding, the object beam is spatially separated into sub-beams of a plurality of wavelengths after being dispersed by the diffraction element 2, and for simplicity of description, three of the sub-beams of different wavelengths, namely, the first wavelength sub-beam a1, the second wavelength sub-beam a2, and the third wavelength sub-beam a3 are taken. a1, a2 and a3 are focused on the exchange engine 3 by a curved mirror 6. The optical system has aberrations (aberrations are deviations from the ideal condition of gaussian optics in an actual optical system, which are caused by the inconsistency of the results obtained for non-paraxial ray-tracing and those obtained for paraxial ray-tracing), and the focal points c1, c2 and c3 of a1, a2 and a3 are distributed in a focal plane, the projection of which in the dispersive plane y-z is a curve in fig. 9. The incident beam is a gaussian beam, and the positions of the focus points c1, c2, and c3 are the positions of the beam waists of a1, a2, and a3, respectively. The beam waist positions c1, c2 and c3 of a1, a2 and a3 have different distances d1, d2, d3 with respect to the surface of the exchange engine 3. According to the formula of divergence of Gaussian beams 
It is understood that, for a beam of wavelength λ, the greater the distance d of the beam waist from the surface of the switching engine 3, the spot size w (d) of the spot of the beam on the switching engine 3 is compared to the beam waist spot size w 0 The higher the divergence of (c), i.e. the greater w (d).
In fig. 9, the spots of a1, a2 and a3 on the surface of the exchange engine 3 are b1, b2 and b3, respectively. b1, b2 and b3 have different spot radii (spot radii may also be referred to as spot sizes) w1, w2 and w3 respectively.
In fig. 9, the first wavelength sub-beam a1 is shown by two lines to illustrate that the beam has a certain width.
Fig. 10 shows a dispersion diagram of the target beam. As shown in fig. 10, the target beam diverges in the dispersion plane y-z through the diffraction element 2. For simplicity of description, the frequencies of a1, a2 and a3 are f1, f2 and f3, respectively, and there is an equal frequency interval B between a1, a2 and a3, i.e. b=f2-f1=f3-f 2. As can be appreciated based on the nonlinear dispersion characteristics of the diffraction element 2,
and (3) with
Not equal, the included angle between a2 and a1 is +.>
The included angle between a2 and a3 is +.>
Fig. 11 shows a schematic of the spots on the switching engine 3. As shown in fig. 11, the first wavelength sub-beam a1, the second wavelength sub-beam a2 and the third wavelength sub-beam a3 are reflected in parallel by the curved mirror 6 to the switching engine 3, and spots, respectively, a first spot q1, a second spot q2 and a third spot q3 are formed on the surface of the switching engine 3, the distance between the centers of the first spot q1 and the second spot q2 is p1, the distance between the centers of the second spot q2 and the third spot q3 is p2, and the distance between the two spots is typically 
Where f is the focal length of the curved mirror 6, < >>
The angle between the beams forming the two spots before entering the curved mirror 6. Due to->
And->
Are not equal, so p1 and p2 are not identical.
The bandwidth of the channel of the wavelength selective device is used to describe the steepness of the filter curve of the wavelength selective device, and is defined in terms of the bandwidth of the-3 dB position of the insertion loss spectrum of the channel, referred to as the-3 dB bandwidth, see fig. 12. The higher the 3dB bandwidth, the steeper the filtering curve, and the less the filtering loss damage to the signal. The embodiments of the present application are illustrated with-3 dB bandwidth as an example. It has been shown by research that, in the case of a fixed channel spacing B, for a channel, the spot size w corresponding to the channel and p corresponding to the channel determine the-3 dB bandwidth of the channel, w being the spot size of the beam of the central wavelength of the channel on the surface of the switching engine 3, p being the size of the beam of the channel covering the switching engine 3 in the dispersion direction, i.e. the distance between the spots of the beam of the boundary wavelength of the channel on the switching engine 3, simply referred to as the spot distance, e.g. a larger p/w corresponds to a larger-3 dB bandwidth. The different beams of the wavelength selective device differ in p/w, indicating that the bandwidths of the different channels differ. Therefore, for one channel of the wavelength selection device, the bandwidth of the channel can be adjusted by the spot size w and p of the light beam of the channel, and as the formula (1) can know that the spot size is related to the beam waist, the distance from the beam waist to the surface of the switching engine 3 can be adjusted by setting the reticle spacing at the incidence position of the light beam, so that the adjustment of the spot size is realized, and the adjustment of the bandwidth of the channel is further realized.
Further, since the chromatic dispersion of the first diffraction grating 21 and the second diffraction grating 22 is not uniform, the two light fluxes divided by the polarization component 5 into the light fluxes of the same wavelength are different in the corresponding p/w on the switching engine 3. The bandwidth versus wavelength and polarization distribution of a conventional wavelength selective device is given in fig. 13. As can be seen from fig. 13, the bandwidths of the different channels of the wavelength selective device are different in the same polarization state, and the bandwidths of the same channels in different polarization states are generally different. For example, in a wavelength selective device based on a diffraction grating of the same reticle pitch, b=100 GHz, the minimum bandwidth of the wavelength selective device is 92.2GHz, the bandwidth of the short wavelength channel is lower than that of the long wavelength channel for the p-polarization state, the maximum bandwidth difference is 0.6GHz, the bandwidth of the short wavelength channel is higher than that of the long wavelength channel for the s-polarization state, the maximum bandwidth difference is 0.2GHz, and the maximum bandwidth difference is 0.6GHz considering the polarization state and the wavelength. In the embodiments of the present application, short wavelength and long wavelength are a relative concept, short wavelength being smaller than long wavelength.
In the embodiment of the present application, the reason why the bandwidth of the channel in the first polarization state can be adjusted by the reticle pitch at the first incident position of the first diffraction grating 21 is as follows: the reticle pitch of the first diffraction grating 21 affects the wavefront phase of the first sub-beam, so that the imaging characteristics of the switching engine 3 change, and thus affects the spot size and position of the beam waist, which affects the distance from the beam waist to the switching engine 3, which affects the spot size of the beam forming a spot on the switching engine 3, and the spot size of the beam of the channel and p affects the bandwidth of the channel, so that the bandwidth of the channel can be adjusted by setting the reticle pitch, p being the size of the channel beam covering the switching engine 3 in the dispersion direction, which is equal to the distance between the spot centers of the spot forming a spot on the switching engine 3 for the beam of the boundary wavelength of the channel. The bandwidth of the channel in the second polarization state is likewise adjusted by the pitch of the reticle of the second diffraction grating 22. Therefore, for one channel of the wavelength selection device, the bandwidth of the channel can be adjusted by the light spot size w and p of the light beam of the channel, and as the formula (1) can know that the light spot size is related to the beam waist, the distance from the beam waist to the surface of the LCOS phase space modulator can be adjusted by setting the reticle distribution of the first diffraction region and the second diffraction region, so that the adjustment of the light spot size is realized, and the adjustment of the bandwidth of the channel is further realized. In the embodiment of the application, the reticle pitches of the first diffraction region and the second diffraction region can be set through simulation. See the description below for specific arrangements.
The process of obtaining grating parameters of the diffraction element 2 by a simulation, including reticle distribution information of the diffraction element 2, which is used to reflect the reticle pitch, is described below.
The method of determining the grating parameter may be performed by a determining device, optionally a hardware device, such as a computer device, e.g. a terminal, a server, etc. Alternatively, the determining means is a software means, such as a set of software programs running on hardware means.
Fig. 14 shows a schematic configuration of the hardware device when it is determined that the device is a computer apparatus. As shown in fig. 14, the computer device 1400 is optionally implemented by a general bus architecture. The computer device 1400 includes at least one processor 1401, a communication bus 1402, a memory 1403, and at least one network interface 1404.
The processor 1401 is, for example, a general-purpose central processing unit (central processing unit, CPU), a network processor (network processer, NP), a graphics processor (Graphics Processing Unit, GPU), a neural-network processor (neural-network processing units, NPU), a data processing unit (Data Processing Unit, DPU), a microprocessor, or one or more integrated circuits for implementing the aspects of the present application. For example, the processor 1401 includes an application-specific integrated circuit (ASIC), a programmable logic device (programmable logic device, PLD), or a combination thereof. PLDs are, for example, complex programmable logic devices (complex programmable logic device, CPLD), field-programmable gate arrays (field-programmable gate array, FPGA), general-purpose array logic (generic array logic, GAL), or any combination thereof.
A communication bus 1402 is used to transfer information between the above-described components. The communication bus 1402 can be classified into an address bus, a data bus, a control bus, and the like. For ease of illustration, only one thick line is shown in fig. 14, but not only one bus or one type of bus.
The Memory 1403 is, for example, but not limited to, a read-only Memory (ROM) or other type of static storage device that can store static information and instructions, a random access Memory (random access Memory, RAM) or other type of dynamic storage device that can store information and instructions, an electrically erasable programmable read-only Memory (electrically erasable programmable read-only Memory, EEPROM), a compact disc (compact disc read-only Memory) or other optical disk storage, a compact disc storage (including compact disc, laser disc, optical disc, digital versatile disc, blu-ray disc, etc.), a magnetic disk storage medium, or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and that can be accessed by a computer. The memory 1403 is, for example, independent and is connected to the processor 1401 via the communication bus 1402. Memory 1403 may also be integrated with processor 1401.
Optionally, the memory 1403 is used to hold data needed in determining grating parameters, such as storing reticle distribution information of the diffraction element 2.
The network interface 1404 uses any transceiver-like device for communicating with other devices or communication networks. Network interface 1404 includes a wired network interface and may also include a wireless network interface. The wired network interface may be, for example, an ethernet interface. The ethernet interface may be an optical interface, an electrical interface, or a combination thereof. The wireless network interface may be a wireless local area network (wireless local area networks, WLAN) interface, a network interface of a cellular network, a combination thereof, or the like.
In a particular implementation, as an example, processor 1401 may include one or more CPUs.
In a particular implementation, as an example, the computer device 1400 may include multiple processors. Each of these processors may be a single-core processor (single-CPU) or a multi-core processor (multi-CPU). A processor herein may refer to one or more devices, circuits, and/or processing cores for processing data (e.g., computer program instructions).
In a particular implementation, as an example, computer device 1400 may also include output devices and input devices. An output device communicates with the processor 1401 and may display information in a variety of ways. For example, the output device may be a liquid crystal display (liquid crystal display, LCD), a light emitting diode (light emitting diode, LED) display device, a Cathode Ray Tube (CRT) display device, or a projector (projector), or the like. An input device is in communication with the processor 1401 and receives input from a user in a variety of ways. For example, the input device may be a mouse, a keyboard, a touch screen device, a sensing device, or the like.
In some embodiments, the memory 1403 is used to store program code 14031 for performing the determination of raster parameters herein, and the processor 1401 executes the program code 14031 stored in the memory 1403. That is, computer device 1400 may implement method embodiments to provide a method of determining grating parameters by processor 1401 and program code 14031 in memory 1403.
As shown in fig. 15, a flow of determining the grating parameter is provided, and in the flow shown in fig. 15, description is given taking the determination device as an example of a terminal.
In step 1501, grating parameters of the diffraction component 2 in the wavelength selective device are obtained, the grating parameters including reticle distribution information of the diffraction component 2.
In this embodiment, an application program for determining the grating parameter is installed on the terminal, and when the determination of the grating parameter is started, a technician (hereinafter referred to as a user) triggers the start of the application program. An input box of grating parameters is provided in the application, into which the user inputs the grating parameters of the diffraction element 2. The grating parameter is an initial grating parameter, and the initial grating parameter is a preset grating parameter, for example, the initial grating parameter may be an equidistant reticle pitch.
In step 1502, based on the grating parameters, the spot size and the spot distance corresponding to each channel of the wavelength selection device are determined, and for the target channel, the spot size corresponding to the target channel is the size of the spot on the switching engine 3 of the light beam with the center wavelength of the target channel, and the spot distance corresponding to the target channel is the distance between the spots on the switching engine 3 of the light beam with the boundary wavelength of the target channel.
In this embodiment, after the terminal obtains the grating parameter input by the user, the grating parameter may be used to simulate the spot size and the spot distance corresponding to each channel of the wavelength selection device when the grating parameter is used. For a target channel of the wavelength selection device, the target channel has a center wavelength and a boundary wavelength, the center wavelength is equal to an average value of the boundary wavelengths, the boundary wavelength is a maximum wavelength and a minimum wavelength of the target channel, a spot size corresponding to the target channel is a radius of a spot on the switching engine 3 of a light beam with the center wavelength in the wavelength selection device, a spot distance corresponding to the target channel is a distance between spots on the switching engine 3 of the light beam with the boundary wavelength, and the target channel is any channel of the wavelength selection device. For example, as shown in fig. 11, the boundary wavelength of the target channel is the wavelength of a1 and the wavelength of a2, and the spot distance corresponding to the target channel is p1.
Illustratively, the grating parameters of the diffraction element 2 include the reticle distribution information of the first diffraction region and the reticle distribution information of the second diffraction region when corresponding to the wavelength selective device shown in fig. 7.
Illustratively, when the diffraction member 2 includes the first diffraction grating 21 and the second diffraction grating 22, the first diffraction region belongs to the first diffraction grating 21, and the second diffraction region belongs to the second diffraction grating 22. The grating parameters also include the type of substrate material of the first diffraction grating 21 and the type of substrate material of the second diffraction grating 22. In this way, when determining the grating parameters, the substrate material type is considered, which is equivalent to considering one degree of freedom, so that the finally obtained target grating parameters can be more accurate.
For example, in the case that the first diffraction region and the second diffraction region are parallel and do not overlap, the grating parameter may further include a distance between the first diffraction region and the second diffraction region, so that when determining the grating parameter, the distance between the first diffraction region and the second diffraction region is also considered, which is equivalent to considering one more degree of freedom, so that the finally obtained target grating parameter is more accurate.
Illustratively, the grating parameters may also include the distance of the first diffraction region from the second diffraction region, the type of base material of the first diffraction grating 21, and the type of base material of the second diffraction grating 22.
And step 1503, adjusting grating parameters based on the light spot size and the light spot distance corresponding to each channel to obtain target grating parameters meeting the bandwidth constraint condition.
Wherein the bandwidth constraint is used to indicate the condition that the bandwidth of the wavelength selective device should meet. Such as bandwidth equalization of wavelength selective devices, etc.
In this embodiment, the terminal acquires a bandwidth constraint condition stored in advance, the bandwidth constraint condition being used to constrain the grating parameters of the diffraction element 2. And then the terminal adjusts the grating parameters by using the light spot size and the light spot distance corresponding to each channel, so that the bandwidth of the wavelength selection device under the grating parameters meets the bandwidth constraint condition, and the grating parameters at the moment are the target grating parameters finally obtained. For example, the terminal determines the bandwidth of the wavelength selective device by using the spot size and the spot distance corresponding to each channel, and determines whether the bandwidth of the wavelength selective device meets the bandwidth constraint condition. If the bandwidth meets the bandwidth constraint condition, determining the grating parameter meeting the bandwidth constraint condition as a target grating parameter, if the bandwidth does not meet the bandwidth constraint condition, returning to adjust the grating parameter, determining the light spot size and the light spot distance corresponding to each channel by using the adjusted grating parameter, determining the bandwidth of the wavelength selection device by using the light spot size and the light spot distance corresponding to each channel, and executing the processing of judging whether the bandwidth of the wavelength selection device meets the bandwidth constraint condition until the target grating parameter meeting the bandwidth constraint condition is obtained. After obtaining the target grating parameters, the terminal can display the target grating parameters. The diffraction element 2 may be subsequently fabricated using the target grating parameters, and when the fabricated diffraction element 2 is applied in a wavelength selective device, the bandwidth of the wavelength selective device satisfies the bandwidth constraint.
In order to meet the bandwidth requirements of the wavelength selective device channels in different scenarios, different bandwidth constraints can be set in different scenarios. The first polarization state is p-polarization state, and the second polarization state is s-polarization state, as described below.
First scenario: when the wavelength selection device is applied to the ROADM, in order to make the transmission performance of the optical transmission system of the ROADM for the light beams with different wavelengths relatively small, the bandwidth of the channel of the wavelength selection device can be balanced so that the filtering performance of the wavelength selection device for the light beams with different wavelengths is balanced. The flow of equalizing the bandwidth of the wavelength selective device channels is shown in fig. 16.
In step 1601, grating parameters of the diffraction element 2 in the wavelength selective device are obtained, where the grating parameters include reticle distribution information of a first diffraction region of the diffraction element 2 and reticle distribution information of a second diffraction region of the diffraction element 2.
The processes from step 1601 to step 1602 are referred to as a flow shown in fig. 15, and are not described herein.
In this embodiment, for the target channel, the terminal divides the spot distance corresponding to the target channel by the spot size corresponding to the target channel to obtain the parameter determining the bandwidth of the target channel.
It should be noted that, after the input light beam of the wavelength selection device enters the wavelength selection device, the light beam is divided into two polarized light beams by the polarization component, so for the target channel, there are two corresponding spot sizes of the target channel, namely, the corresponding spot size in the first polarized state and the corresponding spot size in the second polarized state, and there are two corresponding spot distances of the target channel, namely, the corresponding spot distance in the first polarized state and the corresponding spot distance in the second polarized state.
In this embodiment, after determining the bandwidths of each channel in the two polarization states, it is determined whether the bandwidths of the channels of the wavelength selection device in the first polarization state are balanced, and whether the bandwidths of the channels in the second polarization state are balanced.
In step 1605, if the bandwidth differences of the channels of the wavelength selection device are balanced, the process of determining the grating parameters is ended, and if the bandwidth differences of the channels of the wavelength selection device are not balanced, step 1601 is executed again until the grating parameters that balance the bandwidth differences of the channels of the wavelength selection device are obtained.
In this embodiment, whether the bandwidth difference of the channels of the wavelength selective device is balanced refers to whether the bandwidth difference in the two polarization states is balanced.
Illustratively, when measuring whether the bandwidth differences of the channels of the wavelength selective device are balanced, an evaluation Factor (FOM) 1 may be used, and the FOM1 may be that adjacent wavelength channels have a minimum difference in the corresponding p/w in each polarization state.
After determining the grating parameters of the diffraction element 2 using the procedure shown in fig. 16, a curve of the channel of the WSS in p-polarization and s-polarization at the-3 dB position is fitted, see fig. 17. As can be seen from fig. 17, based on the diffraction element 2 in the embodiment of the present application, the bandwidth of the channel of the wavelength selective device is 92.72GHz at the channel interval b=100 GHz, and the bandwidth is improved by 0.5GHz compared with the bandwidth difference of the conventional wavelength selective device in fig. 13. And for the p-polarization and s-polarization, the bandwidths of the short wavelength and long wavelength channels are balanced, the bandwidth difference is less than 0.08GHz, and the bandwidth difference is reduced by 7 times compared with that shown in fig. 13.
The second scenario: in a dense wavelength division multiplexing system, a wavelength selection device in the system has different responses to light beams with different wavelengths, and the bandwidth of a channel of the wavelength selection device can be designed according to the requirement of the system. For example, the bandwidth of the short wavelength channels in the system in the first polarization state is greater than the bandwidth of the long wavelength channels in the first polarization state, so the trend of the bandwidth variation with wavelength can be adjusted such that the bandwidth of the short wavelength channels in the wavelength selective device in the first polarization state is less than the bandwidth of the long wavelength channels in the first polarization state to balance the bandwidth of the short wavelength channels and the bandwidth of the long wavelength channels in the system. For another example, in the system, the bandwidth of the short wavelength channels in the second polarization state is less than the bandwidth of the long wavelength channels in the second polarization state, so the trend of the bandwidth variation with wavelength can be adjusted so that the bandwidth of the short wavelength channels in the wavelength selective device in the second polarization state is greater than the bandwidth of the long wavelength channels in the second polarization state to balance the bandwidth of the short wavelength channels and the bandwidth of the long wavelength channels in the system. In the second scenario, the procedure for determining the grating parameters is as follows.
In step 1701, grating parameters of the diffraction element 2 in the wavelength selective device are obtained, the grating parameters comprising reticle distribution information of a first diffraction region of the diffraction element 2 and reticle distribution information of a second diffraction region of the diffraction element 2.
Step 1702, determining a spot size and a spot distance corresponding to each channel of the wavelength selection device based on the grating parameters, wherein for a target channel, the spot size corresponding to the target channel is the size of a spot on the switching engine 3 of a light beam with the center wavelength of the target channel in the wavelength selection device, and the spot distance corresponding to the target channel is the distance between spots on the switching engine 3 of a light beam with the boundary wavelength of the target channel.
The process from step 1701 to step 1702 is referred to as a flow shown in fig. 15, and will not be described herein.
Step 1703, determining a bandwidth of each channel based on the corresponding spot size and spot distance of each channel.
The process of step 1703 is referred to as the process of step 1603 in fig. 16, and will not be described again here.
Step 1704, determining whether the first bandwidth difference and the second bandwidth difference of the wavelength selective device are equal.
In this embodiment, the bandwidth value of the channel with the smallest center wavelength of the WSS in the first polarization state is determined, and the bandwidth value of the channel with the largest center wavelength of the WSS in the first polarization state is determined, and the two bandwidth values are differenced to obtain a first bandwidth difference value. And determining the bandwidth value of the channel with the minimum center wavelength of the WSS in the second polarization state, determining the bandwidth value of the channel with the maximum center wavelength of the WSS in the second polarization state, and taking the difference between the two bandwidth values to obtain a second bandwidth value. And judging whether the first bandwidth value is equal to the second bandwidth value.
Step 1705, if the first bandwidth difference is equal to the second bandwidth difference, the process of determining the grating parameter is ended, and if the first bandwidth difference is not equal to the second bandwidth difference, the process returns to step 1701 until the first bandwidth difference is equal to the second bandwidth difference, and the target grating parameter is obtained.
For example, when the first bandwidth difference is determined to be the same as the second bandwidth difference, it can be considered that the p/w of the channel of the minimum center wavelength and the p/w of the channel of the longest center wavelength have a fixed difference value Δ1 in two orthogonal polarization states.
For example, when Δ1 is smaller than 0, by the diffraction element 2 provided in steps 1701 to 1705, the bandwidth of the channel of the smallest wavelength of the wavelength selection device is made smaller than the bandwidth of the channel of the longest wavelength, and referring to the graph of the bandwidth versus wavelength of the channel of the wavelength selection device shown in fig. 18, the bandwidth distribution shows a tendency that the bandwidth of the short wavelength channel is lower than the bandwidth of the long wavelength channel, and the tendency is uncorrelated with the polarization state of the light beam. In this way, a system with short wavelength transmission performance better than long wavelength transmission performance can be balanced.
When Δ1 is greater than 0, the bandwidth of the channel of the wavelength selective device having the largest wavelength is made smaller than the bandwidth of the channel of the wavelength selective device having the smallest wavelength by the diffraction element 2 provided in steps 1701 to 1705, and the bandwidth distribution shows a tendency that the bandwidth of the short wavelength channel is higher than the bandwidth of the long wavelength channel and the tendency is uncorrelated with the polarization state of the light beam, see the bandwidth versus wavelength diagram of the channel of the wavelength selective device shown in fig. 19. In this way, a system with short wavelength transmission performance lower than long wavelength transmission performance can be equalized.
Third scenario: some optical devices (such as transmission optical fibers and the like) in an optical transmission system of the ROADM have polarization correlation, and the polarization state change in the light beam transmission process can influence the transmission performance of the optical transmission system, so that the bandwidth distribution adjustment under different polarization states of the same channel is beneficial to balancing the influence of different polarization states on the transmission performance of the optical transmission system. For example, the bandwidth of the short wavelength channels in the system is greater in the first polarization than the bandwidth of the long wavelength channels in the first polarization, the bandwidth of the short wavelength channels in the system is less in the second polarization than the bandwidth of the long wavelength channels in the second polarization, so the trend of the bandwidth as a function of wavelength can be adjusted such that the bandwidth of the WSS short wavelength channels in the first polarization is less than the bandwidth of the long wavelength channels in the first polarization, and such that the bandwidth of the short wavelength channels in the WSS is greater in the second polarization than the bandwidth of the long wavelength channels in the second polarization to balance the bandwidth of the short wavelength channels and the bandwidth of the long wavelength channels in the system. In a third scenario, the procedure for determining grating parameters is as follows.
In step 1901, grating parameters of the diffraction element 2 in the wavelength selective device are obtained, the grating parameters including reticle distribution information of a first diffraction region of the diffraction element 2 and reticle distribution information of a second diffraction region of the diffraction element 2.
Step 1902, determining, based on the grating parameters, a spot size and a spot distance corresponding to each channel of the wavelength selection device, where, for the target channel, the spot size corresponding to the target channel is the size of a spot on the switching engine 3 of a light beam with a center wavelength of the target channel, and the spot distance corresponding to the target channel is the distance between spots on the switching engine 3 of a light beam with a boundary wavelength of the target channel.
The process from step 1901 to step 1902 is referred to as the flow shown in fig. 15, and will not be described herein.
In step 1903, the bandwidth of each channel is determined based on the corresponding spot size and spot distance for each channel.
The process of step 1903 is referred to as the process of step 1603 in fig. 16, and will not be described again here.
In step 1904, it is determined whether the first bandwidth difference and the second bandwidth difference of the wavelength selective device are opposite numbers to each other.
In this embodiment, the manner in which the first bandwidth difference and the second bandwidth difference are determined is referred to as step 1604. And judging whether the first bandwidth value and the second bandwidth value are opposite numbers or not.
In step 1905, if the first bandwidth difference value and the second bandwidth difference value are opposite, the process of determining the grating parameter is ended, and if the first bandwidth difference value and the second bandwidth difference value are not opposite, step 1901 is executed again until the first bandwidth difference value and the second bandwidth difference value are opposite, and the target grating parameter is obtained.
For example, when determining whether the first bandwidth difference and the second bandwidth difference are opposite to each other, it may be considered that the p/w of the channel of the minimum center wavelength and the p/w of the channel of the longest center wavelength have a fixed and opposite difference value Δ2 in two orthogonal polarization states.
For example, when Δ2 is smaller than 0, using the diffraction element 2 set in steps 1901 to 1905 may cause the bandwidth of the channel of the smallest wavelength to be smaller than the bandwidth of the channel of the longest wavelength in the first polarization state, and the bandwidth of the channel of the smallest wavelength to be larger than the bandwidth of the channel of the longest wavelength in the second polarization state, see the graph of the bandwidth versus wavelength of the channel of the wavelength selection device shown in fig. 20. In this way, the wavelength distribution in different polarization states can be equalized.
When Δ2 is greater than 0, using the diffraction element 2 set in steps 1901 to 1905 will cause the bandwidth of the channel with the largest wavelength to be greater than the bandwidth of the channel with the smallest wavelength in the first polarization state, and the bandwidth of the channel with the smallest wavelength to be less than the bandwidth of the channel with the longest wavelength in the second polarization state, which is shown in the graph of the bandwidth versus wavelength for the channel of the wavelength selection device in fig. 21. In this way, the wavelength distribution in different polarization states can be equalized.
Fourth scenario: in some cases, the bandwidth difference between different polarization states is required to be constant for channels of arbitrary wavelength. For example, in an optical transmission system, for a channel of any wavelength, the bandwidth difference between the first polarization state and the second polarization state is the target threshold, so the tendency of the bandwidth to change with the wavelength can be adjusted such that, for a channel of any wavelength of the wavelength selection device, the bandwidth difference between the first polarization state and the second polarization state approaches the target threshold. In a fourth scenario, the procedure for determining grating parameters is as follows.
Step 2201, obtaining grating parameters of the diffraction element 2 in the wavelength selective device, where the grating parameters include reticle distribution information of a first diffraction region of the diffraction element 2 and reticle distribution information of a second diffraction region of the diffraction element 2.
Step 2202, determining, based on the grating parameters, a spot size and a spot distance corresponding to each channel of the wavelength selection device, where, for the target channel, the spot size corresponding to the target channel is the size of a spot on the switching engine 3 of the light beam with the center wavelength of the target channel, and the spot distance corresponding to the target channel is the distance between spots on the switching engine 3 of the light beam with the boundary wavelength of the target channel.
The processes from step 2201 to step 2202 refer to the flow shown in fig. 15, and are not described here again.
Step 2203 determines a bandwidth of each channel based on the corresponding spot size and spot distance of each channel.
The process of step 2203 is referred to as the process of step 1603 in fig. 16, and will not be described here.
At step 2204, it is determined whether a bandwidth difference of each channel of the wavelength selective device in the first polarization state and the second polarization state is a target threshold.
In this embodiment, for a target channel of a wavelength selective device, a bandwidth of the target channel in a first polarization state is determined, and a bandwidth of the target channel in a second polarization state is determined. And determining the difference value of the two bandwidths, obtaining the bandwidth difference value of the target channel in the first polarization state and the second polarization state, and judging the size relation between the bandwidth difference value and the target threshold value.
In step 2205, if the bandwidth difference of each channel in the first polarization state and the second polarization state is the target threshold, the process of determining the grating parameter is ended, and if the bandwidth difference of each channel in the first polarization state and the second polarization state is not the target threshold, step 2201 is performed back until the bandwidth difference of each channel in the first polarization state and the second polarization state is the target threshold, and the target grating parameter is obtained.
For example, in determining that the bandwidth difference of each channel in the first polarization state and the second polarization state is the target threshold, the evaluation factor may be set such that the bandwidth difference of each channel in the first polarization state and the second polarization state is the target threshold, for example, the expression of the evaluation factor FOM is as follows:
in this formula, N is the number of channels of the wavelength selective device minus one, i indicates the ith channel, the ith channel and the (i+1) th channel are adjacent channels, p ia For the corresponding light spot distance, w, of the ith channel in the first polarization state ia For the corresponding spot size, p, of the ith channel in the first polarization state ib For the corresponding light spot distance, w, of the ith channel in the second polarization state ib For the corresponding spot size of the ith channel in the second polarization state, Δ3 is the target threshold.
Fig. 22 shows a plot of wavelength versus bandwidth for a channel of a wavelength selective device, with channels of any wavelength having a fixed bandwidth difference of 0.5GHz in two orthogonal polarization states.
Based on the above description, the bandwidth constraint condition is different in each scene, and different evaluation factors can be set for different scenes to determine grating parameters, so that the diffraction component 2 can be suitable for a wavelength selective device.
It should be noted that, the foregoing is described by taking the terminal to determine the grating parameter as an example, and in another implementation, the grating parameter may be determined by the server.
In the embodiment of the application, aiming at the problem of uneven bandwidth distribution of the channels of the wavelength selection device, the bandwidths of the channels of the wavelength selection device are balanced. And compared with the traditional wavelength selection device, only the diffraction component is changed, and the change of the light path of the wavelength selection device is small.
And the bandwidth of the channel of the wavelength selection device can meet the requirements of different scenes by determining grating parameters according to different requirements of the distribution of the bandwidth of the channel of the wavelength selection device in different scenes.
The embodiment of the application also provides a wavelength selection method, and the flow of the method is shown in the light beam transmission process in the wavelength device shown in fig. 2 and 7.
The embodiment of the present application further provides a ROADM, where the ROADM includes at least one wavelength selective device, and one or more wavelength selective devices included in the at least one wavelength selective device are the wavelength selective devices shown in fig. 1 or fig. 7, that is, at least one wavelength selective device shown in the present application is adopted in the ROADM, where the wavelength selective device shown in the present application may be set in the ROADM according to actual needs.
In the embodiment of the present application, an input of one incident light beam is taken as an example, and when a plurality of incident light beams are input, the light beam transmission process is the same as the transmission process of one incident light beam.
The device provided by the embodiment of the application is described below.
Fig. 23 is a block diagram of an apparatus for determining grating parameters according to an embodiment of the present application. The apparatus may be implemented as part or all of an apparatus by software, hardware, or a combination of both. The apparatus provided in the embodiment of the present application may implement the flow shown in fig. 15 in the embodiment of the present application, where the apparatus includes: acquisition module 2310 and determination module 2320, wherein:
an obtaining module 2310, configured to obtain grating parameters of a diffraction element in the wavelength selective device, where the grating parameters include a scribe line pitch at a beam incident position of the diffraction element, and may be specifically configured to implement the obtaining function of step 1501 and perform the implicit steps included in step 1501;
a determining module 2320, configured to determine, based on the grating parameter, a spot size and a spot distance corresponding to each channel of the wavelength selection device, where, for a target channel, the spot size corresponding to the target channel is a size of a spot on the switching engine of a light beam with a central wavelength of the target channel in the wavelength selection device, and the spot distance corresponding to the target channel is a distance between spots on the switching engine of a light beam with a boundary wavelength of the target channel;
The grating parameters are adjusted based on the spot size and the spot distance corresponding to each channel, so as to obtain target grating parameters meeting the bandwidth constraint condition, which can be used for realizing the determining functions of the step 1502 and the step 1503 and executing the hidden steps included in the step 1502 and the step 1503.
The detailed process of determining the grating parameters by the device for determining the grating parameters shown in fig. 23 is described in the previous embodiments, and will not be repeated here.
In some embodiments, a computer program product is provided that includes computer instructions stored in a computer-readable storage medium. The processor of the computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device performs the flow shown in fig. 15.
Those of ordinary skill in the art will appreciate that the various method steps and elements described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the steps and elements of the various embodiments have been described generally in terms of functionality in the foregoing description to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Those of ordinary skill in the art may implement the described functionality using different approaches for each particular application, but such implementation is not to be considered as beyond the scope of the present application.
In the several embodiments provided in the present application, it should be understood that the disclosed system architecture, apparatus, and method may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, and for example, the division of the modules is merely a logical function division, and there may be additional divisions when actually implemented, for example, multiple modules or components may be combined or integrated into another system, or some features may be omitted or not performed. In addition, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices, or modules, or may be an electrical, mechanical, or other form of connection.
The modules illustrated as separate components may or may not be physically separate, and components shown as modules may or may not be physical modules, i.e., may be located in one place, or may be distributed over multiple network modules. Some or all of the modules may be selected according to actual needs to achieve the purposes of the embodiments of the present application.
In addition, each module in each embodiment of the present application may be integrated into one processing module, or each module may exist alone physically, or two or more modules may be integrated into one module. The integrated modules may be implemented in hardware or in software.
The integrated module, if implemented in the form of a software functional module and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application is essentially or a part contributing to the prior art, or all or part of the technical solution may be embodied in the form of a software product stored in a storage medium, including several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method in the various embodiments of the present application. And the aforementioned storage medium includes: a usb disk, a removable hard disk, a ROM, a RAM, a magnetic disk, or an optical disk, etc.
The terms "first," "second," and the like in this application are used for distinguishing between similar elements or items having substantially the same function and function, and it should be understood that there is no logical or chronological dependency between the terms "first," "second," and no limitation on the amount or order of execution. It will be further understood that, although the following description uses the terms first, second, etc. to describe various elements, these elements should not be limited by the terms. These terms are only used to distinguish one element from another element. For example, a first beam may be referred to as a second beam, and similarly, a second beam may be referred to as a first beam, without departing from the scope of the various examples. The first and second light beams may both be light beams and, in some cases, may be separate and distinct light beams.
The term "at least one" means one or more, and the term "plurality" means two or more.
The foregoing description is merely a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think about various equivalent modifications or substitutions within the technical scope of the present application, and these modifications or substitutions are all covered by the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (17)
1. A wavelength selective device, characterized in that it comprises an input port (1), a diffraction element (2), a switching engine (3) and an output port (4);
the input port (1) is used for inputting an incident light beam;
the pitch of the reticle at the beam incidence position on the diffraction element (2) is not exactly the same, and is related to the bandwidth of the channel of the wavelength selective device;
the diffraction element (2) is used for dispersing the incident light beam into a plurality of sub-light beams, and the wavelength of each sub-light beam is different;
the switching engine (3) is configured to output at least one sub-beam of the plurality of sub-beams to the output port (4).
2. The wavelength selective device according to claim 1, characterized in that the wavelength selective device further comprises a polarizing component (5);
the polarization component (5) is used for separating the incident light beam into a first light beam with a first polarization state and a second light beam with a second polarization state, and converting the first light beam and the second light beam into the same polarization state, wherein the first polarization state is orthogonal to the second polarization state;
the diffraction element (2) has a first diffraction region in which the reticle pitch at a first entrance position of the first light beam is not exactly the same and a second diffraction region in which the reticle pitch at a second entrance position of the second light beam is not exactly the same, the reticle pitch at the first entrance position being related to the bandwidth of the channel of the wavelength selective device in the first polarization state and the reticle pitch at the second entrance position being related to the bandwidth of the channel of the wavelength selective device in the second polarization state;
the diffraction element (2) is arranged to disperse the first light beam into a plurality of first sub-beams and to disperse the second light beam into a plurality of second sub-beams;
The switching engine (3) is configured to output at least one first sub-beam of the plurality of first sub-beams to the output port (4) and to output at least one second sub-beam of the plurality of second sub-beams to the output port (4), the at least one first sub-beam and the at least one second sub-beam having the same wavelength, and the first sub-beam and the second sub-beam having the same wavelength being output from the same output port (4).
3. The wavelength selective device according to claim 2, wherein the diffraction component (2) comprises a first diffraction grating (21) and a second diffraction grating (22);
the first diffraction region belongs to the first diffraction grating (21) and the second diffraction region belongs to the second diffraction grating (22).
4. A wavelength selective device according to claim 2 or 3, wherein said first and second diffractive regions are located adjacent in the same plane.
5. A wavelength selective device according to claim 2 or 3, wherein the first and second diffraction regions are parallel and non-overlapping.
6. The wavelength selective device of any one of claims 2 to 5, wherein the first diffraction region comprises score lines parallel to the second diffraction region.
7. A wavelength selective device according to any one of claims 2 to 6, wherein the switching engine (3) is a liquid crystal on silicon LCOS phase space modulator.
8. The wavelength selective device of any one of claims 2 to 7, wherein the pitch of the score lines at the first location of incidence equalizes the bandwidth difference of the channels of the wavelength selective device in the first polarization state, and the pitch of the score lines at the second location of incidence equalizes the bandwidth difference of the channels of the wavelength selective device in the second polarization state.
9. The wavelength selective device of any one of claims 2 to 7, wherein the pitch of the score lines at the first location of incidence and the pitch of the score lines at the second location of incidence are such that the channels of the wavelength selective device satisfy a constraint that the first bandwidth difference and the second bandwidth difference are equal or opposite;
the first bandwidth difference value is a bandwidth difference value between a channel with the minimum central wavelength of the wavelength selection device and a channel with the maximum central wavelength of the wavelength selection device in the first polarization state;
the second bandwidth difference is the bandwidth difference between the channel with the minimum center wavelength and the channel with the maximum center wavelength in the second polarization state.
10. The wavelength selective device of any one of claims 2 to 7, wherein the pitch of the score lines at the first location of incidence and the pitch of the score lines at the second location of incidence are such that each channel of the wavelength selective device satisfies a constraint that the bandwidth difference is equal to a target threshold, the bandwidth difference of each channel being the difference in bandwidths in the first and second polarization states.
11. A method of wavelength selection, the method being applied to a wavelength selective device, the method comprising:
an input port (1) outputs an incident light beam to a diffraction component (2), wherein the reticle spacing at the light beam incidence position on the diffraction component (2) is not completely the same, and the reticle spacing at the light beam incidence position is related to the bandwidth of a channel of the wavelength selection device;
the diffraction component (2) disperses the incident light beam into a plurality of sub-light beams, each of which has a different wavelength, and outputs the sub-light beams to the switching engine (3);
-the switching engine (3) outputting at least one of the plurality of sub-beams to an output port (4);
the output port (4) outputs the received light beam.
12. The method according to claim 11, wherein the input port (1) inputs an incident light beam to a diffraction element (2), comprising:
the input port (1) outputs an incident light beam to a polarization component (5);
the polarization component (5) separates the incident light beam into a first light beam with a first polarization state and a second light beam with a second polarization state, converts the first light beam and the second light beam into the same polarization state, and outputs the same to the diffraction component (2), wherein the first polarization state is orthogonal to the second polarization state; the diffraction element (2) has a first diffraction region in which the reticle pitch at a first entrance position of the first light beam is not exactly the same and a second diffraction region in which the reticle pitch at a second entrance position of the second light beam is not exactly the same, the reticle pitch at the first entrance position being related to the bandwidth of the channel of the wavelength selective device in the first polarization state and the reticle pitch at the second entrance position being related to the bandwidth of the channel of the wavelength selective device in the second polarization state;
the diffraction element (2) disperses the incident light beam into a plurality of sub-beams, comprising:
The diffraction element (2) disperses the first light beam into a plurality of first sub-beams and outputs the first sub-beams to the switching engine (3), and disperses the second light beam into a plurality of second sub-beams and outputs the second sub-beams to the switching engine (3);
the switching engine (3) outputting at least one of the plurality of sub-beams to an output port (4), comprising:
the switching engine (3) outputs at least one first sub-beam of the plurality of first sub-beams to the output port (4) and outputs at least one second sub-beam of the plurality of second sub-beams to the output port (4), the at least one first sub-beam and the at least one second sub-beam having the same wavelength, and the first sub-beam and the second sub-beam having the same wavelength are output from the same output port (4).
13. The method according to claim 12, wherein the diffraction element (2) comprises a first diffraction grating (21) and a second diffraction grating (22);
the first diffraction region belongs to the first diffraction grating (21) and the second diffraction region belongs to the second diffraction grating (22).
14. The method of claim 12 or 13, wherein the first and second diffraction regions are located adjacent to each other in the same plane.
15. The method of any one of claims 12 to 14, wherein the first diffraction region comprises score lines parallel to the second diffraction region.
16. The method of any of claims 12 to 15, wherein the pitch of the score lines at the first location of incidence equalizes the bandwidth difference of the channels of the wavelength selective device in the first polarization state and the pitch of the score lines at the second location of incidence equalizes the bandwidth difference of the channels of the wavelength selective device in the second polarization state.
17. A reconfigurable optical add drop multiplexer ROADM, characterized in that it comprises at least one wavelength selective device comprising one or more wavelength selective devices as claimed in any one of claims 1 to 10.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111658828.2A CN116413862A (en) | 2021-12-30 | 2021-12-30 | Wavelength selection device, wavelength selection method and ROADM |
| PCT/CN2022/124656 WO2023124374A1 (en) | 2021-12-30 | 2022-10-11 | Wavelength selection device, wavelength selection method and roadm |
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| CN202111658828.2A CN116413862A (en) | 2021-12-30 | 2021-12-30 | Wavelength selection device, wavelength selection method and ROADM |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006106304A (en) * | 2004-10-05 | 2006-04-20 | Fujitsu Ltd | Optical path changeover switch and wavelength selection optical switch |
| JP2013142875A (en) * | 2012-01-12 | 2013-07-22 | Olympus Corp | Wavelength-selective switch |
| CN114594550B (en) * | 2013-05-22 | 2023-12-29 | 菲尼萨公司 | Method of aberration correcting system in optical system |
| JP2015010899A (en) * | 2013-06-27 | 2015-01-19 | キヤノン株式会社 | Wavelength selection filter, wavelength variable light source using the same, optical interference fault meter using the wavelength variable light source, and photodetector using the wavelength selection filter |
| EP3692399B1 (en) * | 2017-10-02 | 2023-06-07 | CSEM Centre Suisse d'Electronique et de Microtechnique SA - Recherche et Développement | Resonant waveguide grating and applications thereof |
| CN114731208A (en) * | 2019-12-31 | 2022-07-08 | 华为技术有限公司 | Wavelength selective switch |
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