CN112543054B - Multichannel optical channel monitoring system and manufacturing method thereof - Google Patents

Abstract

The invention discloses a multichannel optical channel monitoring system and a manufacturing method thereof, belonging to the field of optical communication. Compared with the traditional channel monitoring method, the invention integrates a plurality of optical channels on one optical waveguide based on a device of an integrated waveguide, adopts a plano-convex SiO2 substrate, replaces an external body grating diffraction device in the traditional channel monitoring method with an inclined grating in the waveguide, uses an area array CCD detector to receive optical signals of different channels and different wavelength channels, simultaneously realizes space division multiplexing and wavelength division multiplexing, does not need a collimating lens in a specific direction while realizing the monitoring of the multichannel optical channels, and has high integration level and stable structure.

Description

Multichannel optical channel monitoring system and manufacturing method thereof

Technical Field

The invention belongs to the field of optical communication, and particularly relates to a multichannel optical channel monitoring system and a manufacturing method thereof.

Background

With the rapid development of 5G communication, the construction of optical networks with high channel density and high channel transmission rate is an inevitable trend in the development of the communication field. Dense Wavelength Division Multiplexing (DWDM) and Space Division Multiplexing (SDM) are common means for increasing the number of channels, and are also preferred schemes for capacity expansion of optical communication and optical network systems. For dense wavelength division multiplexing systems, in addition to monitoring the power of each channel, it is also necessary to monitor the wavelength of each channel and the optical signal-to-noise ratio.

The optical channel monitoring technology commonly used in the dense wavelength division multiplexing system at present is to spread light with different wavelengths on space by using the diffraction effect of a grating, and then the light is collimated and focused by a lens group and then received by a detector. The existing optical channel monitoring technology can only be used for monitoring a single core, and cannot realize multi-channel monitoring under space division multiplexing; and such conventional monitoring techniques usually require a separate volume grating and several separate optical lenses to separate and receive the signal light, which makes the monitoring system complicated and susceptible to external interference.

Disclosure of Invention

The present invention provides a multi-channel optical channel monitoring system and a method for making the same, which aims to solve the technical problems that the existing optical channel monitoring system cannot be used for monitoring multi-channel transmission, or the system is too complex, has low integration level, and is easily interfered by the outside world.

To achieve the above object, according to one aspect of the present invention, there is provided a multi-channel optical channel monitoring system including: the device comprises a SiO2 cladding, a light guide layer, a SiO2 substrate and an area array CCD detector which are sequentially distributed from top to bottom; the area array CCD detector is connected with the signal processing module;

the light guide layer is composed of N germanium-doped Si channels; each germanium-doped Si channel is engraved with an inclined grating; the inclined grating and the section vertical to the light path form an included angle of 0-45 degrees;

each row of germanium-doped Si channel and the corresponding row of pixel points of the area array CCD detector are positioned on the same plane;

the upper side of the SiO2 substrate is a plane, and the lower side of the SiO2 substrate is a cylindrical surface; the distance between the area array CCD detector and the SiO2 substrate is the focal length corresponding to the cylindrical lens formed by the SiO2 substrate;

the SiO2 cladding is used for limiting the light path to be transmitted in the light guide layer; the light guide layer is used for transmitting light paths to the inclined grating through the germanium-doped Si channels, so that light with different wavelengths is diffracted into the SiO2 substrate; the SiO2 substrate is used for focusing diffracted light with different wavelengths to different pixel points of the area array CCD detector; each row of pixel points in the area array CCD detector is used for realizing channel monitoring of a corresponding row of germanium-doped Si channels; and the signal processing module is used for extracting the signals detected by the area array CCD detector into spectral signals of different channels.

Further, the gap between adjacent germanium-doped Si channels is filled with SiO2 material.

Further, the signal processing module performs spectrum compensation on light intensity responses at different wavelengths corresponding to the same row of pixel points in the area array CCD detector, and monitoring of channels with different wavelengths is completed.

Furthermore, the area array CCD detector adopts an InGaAs area array detector.

Further, the maximum number C of channels that can be monitored by the multichannel optical channel monitoring system satisfies the following formula:

C＝M×N

wherein N is the number of germanium-doped Si channels, and M is the number of channels with different wavelengths in each germanium-doped Si channel.

Further, the spectral resolution of the multichannel optical channel monitoring system satisfies the following formula:

wherein, δ λ is the spectral resolution, λ is the wavelength of incident light, f is the focal length of the cylindrical lens formed by the SiO2 substrate, D is the length of the tilted grating, D is the height of the SiO2 substrate, Λ is the period of the tilted grating, and n is the refractive index of the germanium-doped Si channel.

According to another aspect of the present invention, there is provided a method for manufacturing the above multichannel optical channel monitoring system, including:

s1, depositing a layer of germanium-doped Si material on the upper side of a SiO2 substrate with the upper side being a plane and the lower side being a cylindrical surface to obtain a first deposition layer;

s2, etching N germanium-doped Si channels on the first deposition layer to obtain a light guide layer;

s3, depositing a SiO2 material on the upper side of the light guide layer to obtain a SiO2 cladding;

s4, writing an inclined grating on the light guide layer; the inclined grating and the section perpendicular to the light path form an included angle of 0-45 degrees.

Furthermore, the inclined grating is engraved on the light guide layer by adopting a laser mask method or a double-beam interference method.

Further, adopt laser mask method to write slope grating on leaded light layer, specifically include:

after beam collimation and beam expansion, laser enters a 45-degree reflector in parallel, is reflected and then penetrates through a cylindrical lens to form a focusing light spot, and is incident on a phase mask plate to form an interference region;

one side of the SiO2 cladding is close to the phase mask plate, and the phase mask plate, the SiO2 cladding, the light guide layer and the SiO2 substrate are rotated for 0-45 degrees together;

and controlling the electric displacement platform to enable the SiO2 cladding, the light guide layer and the SiO2 substrate to move in the direction perpendicular to the electric displacement platform, wherein the moving distance is the distance between adjacent germanium-doped Si channels every time, the laser is closed during moving, the laser is opened after the movement is finished, the light guide layer realizes refractive index modulation in an interference area, and the writing of the inclined grating is finally realized.

Further, the method of writing the inclined grating on the light guide layer by using the double-beam interference method specifically comprises the following steps:

the laser emits laser, the laser enters the 45-degree reflector in parallel, then the beam splitter is split by rotating the adjustable grating, and two beams of split light interfere in the light guide layer after passing through the reflecting lens group;

and controlling the electric displacement platform to enable the SiO2 cladding, the light guide layer and the SiO2 substrate to move in the direction perpendicular to the electric displacement platform, wherein the moving distance is the distance between adjacent germanium-doped Si channels every time, the laser is closed during moving, the laser is opened after the movement is finished, the light guide layer realizes refractive index modulation in an interference area, and the writing of the inclined grating is finally realized.

In general, the above technical solutions contemplated by the present invention can achieve the following advantageous effects compared to the prior art.

Compared with the traditional channel monitoring method, the invention integrates a plurality of optical channels on one optical waveguide based on a device of an integrated waveguide, adopts a plano-convex SiO2 substrate, replaces an external body grating diffraction device in the traditional channel monitoring method with an inclined grating in the waveguide, uses an area array CCD detector to receive optical signals of different channels and different wavelength channels, simultaneously realizes space division multiplexing and wavelength division multiplexing, does not need a collimating lens in a specific direction while realizing the monitoring of the multichannel optical channels, and has high integration level and stable structure.

Drawings

Fig. 1 is a schematic diagram of a conventional optical channel monitoring system;

FIG. 2 is a schematic structural diagram of an embodiment of a multi-channel optical channel monitoring system provided in the present invention;

FIG. 3 is a left side view of a multi-channel optical channel monitoring system provided by the present invention;

FIG. 4 is a diagram of a device for manufacturing a tilted grating by laser masking in a multi-channel optical channel monitoring system according to an embodiment of the present invention;

FIG. 5 is a diagram of a device for two-beam interferometry of tilted gratings in a multi-channel optical channel monitoring system according to an embodiment of the present invention;

the device comprises a substrate 1, a substrate 2, a light guide layer 3, a substrate 2 of SiO, a planar array CCD detector 4, a germanium-doped Si channel 5, an inclined grating 6, a signal processing module 7, a laser 8, a beam expander 9, a 45-degree reflector 10, a cylindrical lens 11, a phase mask plate 12, an electric displacement platform 13, a beam splitter 14, a reflecting lens 15, an adjustable-angle reflecting lens I16, an adjustable-angle reflecting lens II 17, a transmission optical fiber 18, an optical fiber coupler 19, an optical fiber collimator 20, a volume diffraction grating 21, a focusing lens 22 and a linear array detector 23, wherein the substrate 1 is a SiO2 cladding, the light guide layer 2 is a light guide layer, the optical beam expander 9 is a 45-degree reflector 10, the transmission optical fiber 18 is a cylindrical lens, the phase mask plate 12 is a cylindrical lens, the optical fiber collimator 20 is an optical fiber collimator, the volume diffraction grating 21 is a focusing lens, and the linear array detector 23 is a linear array detector.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

As shown in fig. 1, a currently existing optical channel monitoring system includes: the system comprises a transmission optical fiber 18, an optical fiber coupler 19, an optical fiber collimator 20, a volume diffraction grating 21, a focusing lens 22 and a linear array detector 23. The signal light in the transmission optical fiber 18 is divided into two paths after passing through the optical fiber coupler 19, one path is used for channel monitoring, the other path is used for signal transmission, the signal light for channel monitoring is coupled to a free space through the optical fiber collimator 20 and then enters the surface of the body diffraction grating 21 to form diffraction light, and the diffraction light is focused by the focusing lens 22 and then is received by the linear array detector 23. The optical channel monitoring system needs to couple transmission light out of the transmission optical fiber 18, and diffract signal light by the volume diffraction grating in space, so that the optical path of the whole system is complex, and the loss of the signal light is large when the signal light is coupled to a free space and in the diffraction process of the volume diffraction grating, which is not beneficial to monitoring optical signals. If optical channel monitoring of multi-channel signals is to be realized, a plurality of optical fiber collimators, a volume diffraction grating, a focusing lens and a linear array detector are needed to respectively perform collimation, diffraction, focusing and signal receiving on signal light of each channel, and the whole monitoring system is too complex, low in integration level, more in needed devices and high in cost.

Referring to fig. 2 and fig. 3, the present invention provides a multi-channel optical channel monitoring system, including: the device comprises a SiO2 cladding 1, a light guide layer 2, a SiO2 substrate 3, an area array CCD detector 4 and a signal processing module 7. The light guide layer is provided with N germanium-doped Si channels 5, each germanium-doped Si channel 5 is engraved with an inclined grating 6, and the gaps between adjacent germanium-doped Si channels 5 are filled with SiO2 material. The area array CCD detector 4 is an InGaAs area array detector, the response wave band is 900-1700nm, and the resolution is 640 multiplied by 512. The interval of the adjacent germanium-doped Si channels 5 is the same as the interval of the horizontal adjacent pixel points of the area array CCD detector 4, the distance is 20 microns in the embodiment, the number of the horizontal pixel points of the germanium-doped Si channels 5 is the same as that of the horizontal pixel points of the area array CCD detector 4, and the number of the horizontal pixel points is 640 in the embodiment. The length of the tilted grating 6 is 5mm, the period is 748nm, and the tilt angle is 45 degrees. The upper side of the SiO2 substrate 3 is a plane, the lower side is a cylindrical surface, the height is 1cm, and the focal length of the cylindrical lens is 5 mm. The distance between the area array CCD detector and the SiO2 substrate is the focal length corresponding to the cylindrical lens formed by the SiO2 substrate.

In specific application, when light is transmitted to the inclined grating 6 in each germanium-doped Si channel 5, the light is diffracted into the SiO2 substrate 3 at a diffraction angle related to the wavelength, and due to the fact that the bottom of the SiO2 substrate 3 is a cylindrical surface, diffracted light with different wavelengths is focused on different pixel points of the area array CCD detector 4, and therefore monitoring of channels with different wavelengths is completed. Each row of germanium-doped Si channels 5 and each row of pixel points of the area array CCD detector 4 are positioned on the same plane from left to right, namely, one row of pixel points realize the channel monitoring of one germanium-doped Si channel 5.

In this example, the signal processing module 7 is configured to extract the signal detected by the area array CCD detector 4 into spectral signals of different channels, and the longitudinal signal of the area array CCD detector 4 is a spectral signal of each channel, and spectral compensation needs to be performed on light intensity responses at different wavelengths in the signal processing module 7. The transverse signals of the area array CCD detector 4 are signals at the same wavelength of different channels. In this example, the area array CCD detector 4 outputs 512 signals of the 1 st row to the signal processing module 7, obtains a spectrum signal of the first germanium-doped Si channel 5 after spectrum compensation, and then sequentially outputs signals of the 2 nd row, the 3 rd row … … the 640 th row, each row has 512 signals corresponding to the spectrum signals of the 2 nd, the 3 rd … … th germanium-doped Si channel 5.

The spectral resolution of the multichannel optical channel monitoring system in the embodiment satisfies the following formula:

wherein, δ λ is the spectral resolution, λ is the wavelength of the incident light, f is the focal length of the cylindrical lens of the SiO2 substrate 3, D is the length of the tilted grating 6, D is the height of the SiO2 substrate 3, Λ is the period of the tilted grating 6, and n is the refractive index of the germanium-doped Si channel 5. In the embodiment, when the wavelength of the incident light is 1550nm, the spectral resolution is 0.16nm, which reaches the current technical standard of channel monitoring.

The maximum number of channels C that can be monitored satisfies the following equation:

C＝M×N

where N is the number of germanium-doped Si channels 5 and M is the number of different wavelength channels in each germanium-doped Si channel 5. With 0.4nm as the wavelength interval of each transmission channel, the number of channel monitoring that can be achieved within the 40nm wavelength range is 64000.

Compared with the traditional optical channel monitoring system with the height and the width of decimeter magnitude, the optical channel monitoring system has the advantages that the spectral resolution and the channel monitoring number are met, and meanwhile, the stability and the integration are high.

The manufacturing method of the multichannel optical channel monitoring system comprises the steps of depositing a layer of germanium-doped Si material on the upper side of a cylindrical SiO2 substrate 3, etching N germanium-doped Si channels 5 by a reactive ion etching method to obtain a light guide layer 2, and continuously depositing SiO2 material on the upper side of the light guide layer 2 to obtain a SiO2 cladding 1. And writing an inclined grating 6 on the light guide layer 2 by adopting a laser mask method or a double-beam interference method, wherein the inclined direction is the vertical direction.

Fig. 4 shows a laser mask writing device for tilted gratings in the multichannel optical channel monitoring system of the present example. Laser 8 emits laser, after passing through a beam expander 9, the laser enters a 45-degree reflector 10 in parallel, then passes through a cylindrical lens 11 to form a focusing spot, the laser is incident on a phase mask 12 to form an interference region, one side of a SiO2 cladding 1 is close to the phase mask 12, the SiO2 cladding 1, the light guide layer 2 and the SiO2 substrate 3 rotate together for 45 degrees, an electric displacement platform 13 is controlled, the SiO2 cladding 1, the light guide layer 2 and the SiO2 substrate 3 move in the direction perpendicular to the electric displacement platform, the distance of each movement is 20 microns of the distance of an adjacent germanium-doped Si channel 5, the movement is carried out 640 times in total, the laser is closed during the movement, the laser is opened after the movement is finished, the refractive index modulation of the light guide layer 2 is realized in the interference region, and finally the writing of the inclined grating 6 is realized.

Fig. 5 shows a two-beam interference writing device of the tilted grating in the multi-channel optical channel monitoring system of the present embodiment. The laser 8 emits laser light, the laser light enters the 45-degree reflecting mirror 10 in parallel, then the beam splitter 14 is split by rotating the adjustable grating, two beams of split light are emitted towards two directions after passing through the reflecting lens 15, then the two beams of split light are interfered on the light guide layer 2 after passing through the first adjustable-angle reflecting lens 16 and the second adjustable-angle reflecting lens 17 respectively, and the inclination angle of the interference fringes and the light guide layer is 45 degrees by adjusting the angles of the first adjustable-angle reflecting lens 16 and the second adjustable-angle reflecting lens 17. And controlling the electric displacement platform 13 to enable the SiO2 cladding 1, the light guide layer 2 and the SiO2 substrate 3 to move in the direction perpendicular to the electric displacement platform, wherein the moving distance is 20 microns at each time when the distance between the adjacent germanium-doped Si channels 5 is equal to 640 times, the laser is closed during movement, the laser is opened after the movement is finished, the light guide layer 2 realizes refractive index modulation in an interference area, and finally the writing of the inclined grating 6 is realized.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (9)

1. A multi-channel optical channel monitoring system, comprising: the device comprises a SiO2 cladding (1), a light guide layer (2), a SiO2 substrate (3) and an area array CCD detector (4) which are sequentially distributed from top to bottom; wherein, the area array CCD detector (4) is connected with the signal processing module (7);

the light guide layer (2) is composed of N germanium-doped Si channels (5); each germanium-doped Si channel (5) is engraved with an inclined grating (6); the inclined grating and the section vertical to the light path form an included angle of 0-45 degrees;

each row of germanium-doped Si channel (5) and the corresponding row of pixel points of the area array CCD detector (4) are positioned on the same plane;

the upper side of the SiO2 substrate (3) is a plane, and the lower side is a cylindrical surface; the distance between the area array CCD detector and the SiO2 substrate is the focal length corresponding to the cylindrical lens formed by the SiO2 substrate;

the SiO2 cladding is used for limiting the light path to be transmitted in the light guide layer; the light guide layer is used for transmitting light paths to the inclined grating (6) through the germanium-doped Si channels (5), so that light with different wavelengths is diffracted into the SiO2 substrate (3); the SiO2 substrate (3) is used for focusing diffracted light with different wavelengths onto different pixel points of the area array CCD detector (4); each row of pixel points in the area array CCD detector (4) is used for realizing channel monitoring of the corresponding row of germanium-doped Si channels (5); and the signal processing module (7) is used for extracting the signals detected by the area array CCD detector (4) into spectral signals of different channels.

2. The multi-channel optical channel monitoring system as claimed in claim 1, wherein the gaps between adjacent germanium-doped Si channels are filled with SiO2 material.

3. The multi-channel optical channel monitoring system according to claim 1, wherein the signal processing module performs spectral compensation on light intensity responses at different wavelengths corresponding to a same column of pixel points in the area array CCD detector to complete monitoring of channels with different wavelengths.

4. A multi-channel optical channel monitoring system as claimed in claim 3, wherein the area array CCD detector is an InGaAs area array detector.

5. A multi-channel optical channel monitoring system according to any of claims 1-4, wherein the maximum number of channels C that can be monitored by the multi-channel optical channel monitoring system satisfies the following equation:

C＝M×N

wherein N is the number of germanium-doped Si channels, and M is the number of channels with different wavelengths in each germanium-doped Si channel.

6. A multichannel optical channel monitoring system as claimed in claim 5, characterized in that the spectral resolution of the multichannel optical channel monitoring system satisfies the following formula:

wherein, δ λ is the spectral resolution, λ is the wavelength of incident light, f is the focal length of the cylindrical lens formed by the SiO2 substrate, D is the length of the tilted grating, D is the height of the SiO2 substrate, Λ is the period of the tilted grating, and n is the refractive index of the germanium-doped Si channel.

7. A method of manufacturing a multi-channel optical channel monitoring system according to any one of claims 1 to 6, comprising:

s1, depositing a layer of germanium-doped Si material on the upper side of a SiO2 substrate with the upper side being a plane and the lower side being a cylindrical surface to obtain a first deposition layer;

s2, etching N germanium-doped Si channels on the first deposition layer to obtain a light guide layer;

s3, depositing a SiO2 material on the upper side of the light guide layer to obtain a SiO2 cladding;

s4, writing inclined gratings on the light guide layer by adopting a laser mask method or a double-beam interference method; the inclined grating and the section perpendicular to the light path form an included angle of 0-45 degrees.

8. The method according to claim 7, wherein the writing of the slanted grating on the light guide layer by the laser mask method specifically comprises:

after beam collimation and beam expansion, laser enters a 45-degree reflector in parallel, is reflected and then penetrates through a cylindrical lens to form a focusing light spot, and is incident on a phase mask plate to form an interference region;

one side of the SiO2 cladding is close to the phase mask plate, and the phase mask plate, the SiO2 cladding, the light guide layer and the SiO2 substrate are rotated for 0-45 degrees together;

and controlling the electric displacement platform to enable the SiO2 cladding, the light guide layer and the SiO2 substrate to move in the direction perpendicular to the electric displacement platform, wherein the moving distance is the distance between adjacent germanium-doped Si channels every time, the laser is closed during moving, the laser is opened after the movement is finished, the light guide layer realizes refractive index modulation in an interference area, and the writing of the inclined grating is finally realized.

9. The method according to claim 7, wherein the writing of the tilted grating on the light guide layer by the two-beam interference method comprises:

the laser emits laser, the laser enters the 45-degree reflector in parallel, then the beam splitter is split by rotating the adjustable grating, and two beams of split light interfere in the light guide layer after passing through the reflecting lens group;

and controlling the electric displacement platform to enable the SiO2 cladding, the light guide layer and the SiO2 substrate to move in the direction perpendicular to the electric displacement platform, wherein the moving distance is the distance between adjacent germanium-doped Si channels every time, the laser is closed during moving, the laser is opened after the movement is finished, the light guide layer realizes refractive index modulation in an interference area, and the writing of the inclined grating is finally realized.

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