CN114706059A

CN114706059A - Light beam receiving device and light beam receiving method

Info

Publication number: CN114706059A
Application number: CN202210308362.1A
Authority: CN
Inventors: 朱琳; 汪敬
Original assignee: Suteng Innovation Technology Co Ltd
Current assignee: Suteng Innovation Technology Co Ltd
Priority date: 2022-03-25
Filing date: 2022-03-25
Publication date: 2022-07-05

Abstract

The embodiment of the application discloses a light beam receiving device and a light beam receiving method, wherein the light beam receiving device comprises a local oscillator light path and at least one echo light path, each echo light path comprises a mode conversion device, at least two frequency mixers and balance detectors corresponding to the frequency mixers, the local oscillator light path is connected with each frequency mixer, the mode conversion device is connected with each frequency mixer, and each frequency mixer is respectively connected with the balance detectors corresponding to the frequency mixers. According to the embodiment of the application, the first echo light is transmitted by the echo light path, the first echo light is converted into at least two second echo lights in a preset mode, a plurality of detection information of a detection target is determined based on the second echo light and the second local oscillator light, the utilization rate of the received echo signals can be improved by using small mode conversion loss, the influence of a walk-off effect on a receiving system can be further reduced, and the distance measuring capacity of the receiving system can be improved.

Description

Light beam receiving device and light beam receiving method

Technical Field

The present disclosure relates to laser radar technologies, and in particular, to a light beam receiving apparatus and a light beam receiving method.

Background

The frequency modulation continuous wave laser radar has the advantages of strong anti-interference capability, high ranging precision, convenience in integration and the like, is developed rapidly, and is widely applied. In a coaxial system of the scanning structure, a transmission beam and a reflected echo beam have different time differences due to different target distances, so that when the echo beam reaches the surface of the vibrating mirror or the rotating mirror, the vibrating mirror or the rotating mirror rotates by a certain angle, and the echo beam enters a receiving lens and has a certain angle offset compared with the transmission beam, so that a focus point passing through a lens can also be offset, and the offset of the focus point is generally larger as the distance is farther, which is called as walk-off effect.

Disclosure of Invention

The embodiment of the application provides a light beam receiving device and a light beam receiving method, which can convert non-base mode signals in received echo signals into base mode signals with very small conversion loss for transmission, and further can improve the utilization rate of the received echo signals, and further can reduce the influence of walk-off effect on a receiving system, and can improve the distance measuring capability of the receiving system, and the technical scheme is as follows:

in a first aspect, an embodiment of the present application provides a light beam receiving apparatus, including one local oscillator optical path and at least one echo optical path, where each echo optical path includes a mode conversion device, at least two mixers, and a balanced detector corresponding to each mixer, where the local oscillator optical path is connected to each mixer, the mode conversion device is connected to each mixer, and each mixer is connected to the balanced detector corresponding to each mixer; wherein:

the local oscillator optical path is configured to transmit first local oscillator light, divide the first local oscillator light into at least two second local oscillator lights, and transmit each of the second local oscillator lights to each of the echo optical paths;

each echo light path is used for transmitting each first echo light, converting each first echo light into at least two second echo lights in a preset mode, and determining at least two detection information of a detection target based on each second echo light and each second local oscillator light.

In a second aspect, an embodiment of the present application provides a light beam receiving method, which is applied to a light beam receiving device, where the light beam receiving device includes one local oscillator optical path and at least one echo optical path, and each echo optical path includes a mode conversion device, at least two frequency mixers, and a balanced detector corresponding to each frequency mixer; the local oscillator optical paths are respectively connected with the at least two frequency mixers; the mode conversion device is respectively connected with the at least two mixers; each mixer is connected with each balance detector; characterized in that the method comprises:

the local oscillator light path divides the first local oscillator light into at least two second local oscillator lights, and transmits each second local oscillator light to each echo light path respectively;

each first echo light is converted into at least two second echo lights in a preset mode by each echo light path, and at least two pieces of detection information of a detection target are determined based on each second echo light and each second local oscillator light.

The beneficial effects brought by the technical scheme provided by the embodiment of the application at least comprise:

when the scheme of the embodiment of the application is executed, the scheme is applied to a light beam receiving device, the light beam receiving device includes one local oscillation light path and at least one echo light path, each echo light path includes a mode conversion device, at least two mixers and a balanced detector corresponding to each mixer, the local oscillation light path is connected to each mixer, the mode conversion device is connected to each mixer, each mixer is respectively connected to the balanced detector corresponding to each mixer, based on the above devices, the embodiment of the application utilizes the echo light path to transmit first echo light, converts the first echo light into at least two second echo lights in a preset mode, and determines at least two detection information of a detection target based on each second echo light and each second local oscillation light transmitted by the local oscillation light path, and can convert a non-base mode signal in the received echo signal into a base mode for transmission with a small conversion loss, therefore, most energy of the echo signals can be received, the utilization rate of the received echo signals can be improved, the influence of the walk-off effect on a receiving system can be reduced, and the ranging capability of the receiving system can be improved. In addition, the embodiment of the application also supports multi-path echo optical paths, and can be compatible with polarization diversity reception and multi-path splicing, so that the integration level of the silicon-based optoelectronic integrated chip can be increased, and the volume and the cost of a receiving system can be reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic diagram of a light beam receiving device according to an embodiment of the present application;

FIG. 2 is a schematic diagram of another optical beam receiving apparatus provided in the embodiments of the present application;

FIG. 3 is a schematic diagram of another optical beam receiving apparatus provided in an embodiment of the present application;

FIG. 4 is a schematic diagram of another optical beam receiving apparatus provided in the embodiments of the present application;

FIG. 5 is a schematic diagram of another optical beam receiving apparatus provided in an embodiment of the present application;

FIG. 6 is a schematic diagram of another optical beam receiving apparatus provided in the embodiments of the present application;

FIG. 7 is a schematic diagram of another optical beam receiving apparatus provided in an embodiment of the present application;

fig. 8 is a schematic flowchart of a light beam receiving method according to an embodiment of the present application.

Detailed Description

In order to make the objects, features and advantages of the embodiments of the present application more obvious and understandable, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the description of the present application, it is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In the description of the present application, it is noted that, unless explicitly stated or limited otherwise, "including" and "having" and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art. In addition, in the description of the present application, "a plurality" means two or more unless otherwise specified. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.

In the related art, when a walk-off effect exists, a reflected echo signal generates a certain position offset relative to a transmitted signal during receiving, and is difficult to be well coupled into a single-mode optical fiber, so that the reflected echo signal is seriously lost, the receiving rate of the echo signal at a receiving end is reduced, the coupling efficiency of the optical fiber at the receiving end is limited, and the ranging capability of a laser radar system is influenced.

Before describing the embodiments of the present application more clearly, some concepts in the present application will be described in detail to facilitate better understanding of the present application.

The TE0 mode may refer to a fundamental mode of the transverse electric mode in which the electric field direction is perpendicular to the propagation direction.

The TE1 mode may refer to a non-fundamental transverse electric mode in which the electric field direction is perpendicular to the propagation direction.

The TM0 mode may refer to a fundamental transverse magnetic mode in which the magnetic field direction is perpendicular to the propagation direction.

The TM1 mode may refer to a non-fundamental transverse magnetic mode in which the magnetic field direction is perpendicular to the propagation direction.

The present application will be described in detail with reference to specific examples.

Referring to fig. 1, a schematic diagram of a light beam receiving apparatus provided in an embodiment of the present application is illustrated below, where the light beam receiving apparatus includes a local oscillator optical path and an echo optical path, and the echo optical path includes two mixers and two balanced detectors.

As shown in fig. 1, the optical beam receiving apparatus of the embodiment of the present application may include: one local oscillation optical path and one echo optical path. The echo light path comprises a mode conversion device, a mixer 1, a balance detector 1, a mixer 2 and a balance detector 2.

In fig. 1, two output ports of the local oscillation optical path are respectively connected to one input port of the mixer 1 and one input port of the mixer 2, two output ports of the mode conversion device in the echo optical path are respectively connected to the other input port of the mixer 1 and the other input port of the mixer 2, an output port of the mixer 1 is connected to an input port of the balanced detector 1, and an output port of the mixer 2 is connected to an input port of the balanced detector 2.

Based on the connection relationship between the above devices, the principle of the embodiment of the present application is explained below.

It can be understood that first local oscillator light can be transmitted in the local oscillator optical path, and the local oscillator optical path can divide first local oscillator light into two second local oscillator light to and all transmit two local oscillator light to the mixer in the echo optical path. Specifically, the local oscillator optical path may receive the first local oscillator light through the single-mode coupler, and then may divide the first local oscillator light into two second local oscillator lights through the optical splitter.

The first echo light may be transmitted in the echo optical path, and inside the mode conversion device, the first echo light may be first converted into two kinds of echo light in different modes, where one kind of echo light may be echo light in a basic mode, and the other kind of echo light may be echo light in a non-basic mode, further, the echo light in the non-basic mode may be converted into echo light in the basic mode, and further, the mode conversion device may transmit two kinds of echo light in the basic mode, that is, two kinds of second echo light to the two mixers, respectively. Further, in the mixer, the mixer may perform mixing processing on the second echo light and the local oscillator light to obtain mixed light, and the mixer may further transmit the mixed light to the balanced detector. Further, the balance detector may convert the mixed light into an electrical signal, and perform corresponding processing on the electrical signal to obtain detection information of the detection target, where the detection information may include values of parameters such as distance, speed, azimuth, altitude, and attitude. Specifically, the detection information of the detection target is obtained according to the electrical signal, mainly the distance and the speed can be obtained according to the electrical signal, and further, the speed and the distance are subjected to corresponding data processing, so that the values of parameters such as the azimuth, the altitude and the attitude can be obtained.

When the scheme of the embodiment of the application is executed, light in different modes in the echo light can be converted into light in a preset mode through the mode conversion device, mainly non-base mode light is converted into light in a base mode, and because the local oscillator light path usually transmits local oscillator light in the base mode, when the local oscillator light transmitted by the local oscillator light path and the echo light transmitted by the echo light path perform beat frequency in the mixer, the beat frequency of the light in the same mode can achieve a better beat frequency effect, that is, non-base mode signals in the received echo signals can be converted into base mode signals for transmission with very small conversion loss, so that the utilization rate of the received echo signals can be improved, further, the influence of the walk-off effect on a receiving system can be reduced, and the ranging capability of the receiving system can be improved.

Referring to fig. 2, a schematic diagram of a light beam receiving apparatus provided in an embodiment of the present application is shown, where the light beam receiving apparatus includes a local oscillation optical path and an echo optical path, the echo optical path includes two mixers and two balanced detectors, and a mode conversion apparatus in the echo optical path includes a few-mode coupler, a mode demultiplexer, and a mode converter for explanation.

As shown in fig. 2, the optical beam receiving apparatus according to the embodiment of the present application may include a single-mode coupler, an optical splitter, a few-mode coupler, a mode demultiplexer, a mode converter, a mixer 1, a mixer 2, a balanced detector 1, and a balanced detector 2.

In fig. 2, for the local oscillation optical path, an input port of an optical splitter is connected to a single-mode coupler, and two output ports of the optical splitter are respectively connected to an input port of a mixer 1 and an input port of a mixer 2; for an echo optical path, the few-mode coupler is connected with an input port of the mode demultiplexer, two output ports of the mode demultiplexer are connected with two input ports of the mode converter, two output ports of the mode converter are respectively connected with the other input port of the mixer 1 and the other input port of the mixer 2, two output ports of the mixer 1 are connected with the balanced detector 1, and two output ports of the mixer 2 are connected with the balanced detector 2.

It can be understood that, in the local oscillator light path, can adopt polarization maintaining fiber in with first local oscillator optical coupling to single mode coupler, single mode coupler can transmit first local oscillator light to the beam splitter, and further, the beam splitter can carry out beam splitting to first local oscillator light, obtains two second local oscillator light, and the beam splitter can transmit two second local oscillator light respectively to an input port of the mixer 1 of echo light path, an input port of mixer 2. The first local oscillator light transmitted by the single-mode coupler may be an optical signal in a TE0 mode, and the two second local oscillator lights coming out after passing through the optical splitter are still optical signals in a TE0 mode.

In the echo optical path, a few-mode fiber may be selected to couple the first echo light into at least one mode coupler, the few-mode fiber may specifically be a two-mode fiber, at this time, the first echo light may include optical signals in TE0 mode and TE1 mode, and the few-mode coupler may transmit the first echo light including fundamental mode of transverse electric mode and non-fundamental mode transverse electric mode to the mode demultiplexer; inside the mode demultiplexer, the two modes of optical signals contained in the first echo light may be divided into two optical signals transmitted by different optical paths, one optical path may transmit an optical signal of a TE0 mode, and the other optical path may transmit an optical signal of a TE1 mode, for convenience of description, the optical signal of the TE0 mode may be referred to as a second echo light, and the optical signal of the TE1 mode may be referred to as a third echo light, and then, the mode demultiplexer may transmit the second echo light and the third echo light to two different input ports of the mode converter respectively; further, the mode converter may convert the third echo light, i.e. the optical signal in TE1 mode, into the optical signal in TE0 mode, and for convenience of description, the optical signal after the conversion of the third echo light may be referred to as a fourth echo light, and in this case, the fourth echo light and the second echo light are both the optical signal in TE0 mode; further, the mode converter may transmit the second echo light and the fourth echo light to another input port of the mixer 1 and another input port of the mixer 2, respectively; further, the frequency mixer 1 may receive second echo light and second local oscillator light, both of which are optical signals in the TE0 mode, and meanwhile, the frequency mixer 2 may also receive fourth echo light and second local oscillator light, both of which are optical signals in the TE0 mode, and the two frequency mixers may perform frequency mixing processing on a base mode and then transmit the optical signals after frequency mixing to the balanced detector; further, the balance detector may convert the mixed light into an electrical signal, and perform corresponding processing on the electrical signal to obtain detection information of the detection target, where the detection information may include values of parameters such as distance, speed, azimuth, altitude, and attitude. Specifically, the detection information of the detection target is obtained according to the electrical signal, the distance and the speed can be mainly obtained according to the electrical signal, and further, the corresponding data processing is performed on the speed and the distance, so that the values of the parameters such as the azimuth, the altitude, the attitude and the like can be obtained.

It should be noted that, in another embodiment, a few-mode optical fiber may also be a few-mode optical fiber such as a three-mode, a four-mode, a five-mode, and the like, which is not limited in this application.

When the scheme of the embodiment of the application is executed, the few-mode coupler is used for receiving the echo signal, because the mode field of the few-mode coupler is large, under the condition that the walk-off effect exists, the receiving efficiency of the echo signal can be improved, then, the optical signal in the TE1 mode in the echo signal is converted into the optical signal in the TE0 mode by the mode converter, although the conversion loss exists, the loss is small, and when the frequency mixer conducts beat frequency, because the local oscillator light and the echo light are both basic mode signals, a better beat frequency effect can be achieved, that is, the application can improve the receiving efficiency of the echo signal, the utilization rate of the received echo signal can be improved, the influence of the walk-off effect on a receiving system can be reduced, and the distance measuring capability of the receiving system can be improved.

Referring to fig. 3, a schematic diagram of a light beam receiving apparatus provided in an embodiment of the present application is illustrated below, where the light beam receiving apparatus includes one local oscillation optical path and multiple echo optical paths, each echo optical path includes two mixers and two balanced detectors, and a mode conversion apparatus in each echo optical path includes a few-mode coupler, a mode demultiplexer, and a mode converter.

As shown in fig. 3, in the optical beam receiving apparatus according to the embodiment of the present invention, each of the echo optical paths may include a few-mode coupler, a mode demultiplexer, a mode converter, a mixer 1, a mixer 2, a balanced detector 1, and a balanced detector 2. The local oscillation optical path may include a single-mode coupler, a first optical splitter, and a plurality of second optical splitters, where the number of the second optical splitters is equal to the number of the echo optical paths, and fig. 3 shows 2 echo optical paths and 2 second optical splitters for illustration.

In fig. 3, the connection relationship between the devices in each echo optical path can be seen in fig. 2, and is not described herein again. For the local oscillation optical path, the single-mode coupler is connected with the input ports of the first optical splitter, a plurality of output ports of the first optical splitter are respectively connected with the input ports of each second optical splitter, the number of the output ports of the first optical splitter is equal to that of the second optical splitters, and two output ports of each second optical splitter are respectively connected with one input port of the mixer 1 in each echo optical path and one input port of the mixer 2 in each echo optical path.

It can be understood that, in the local oscillator optical path, a polarization maintaining fiber may be adopted to couple the first local oscillator light into the single mode coupler, and the single mode coupler may transmit the first local oscillator light to the first optical splitter; further, the first optical splitter may perform optical splitting processing on the first local oscillator light to obtain a plurality of second local oscillator lights, and the first optical splitter may transmit each of the second local oscillator lights to each of the second optical splitters respectively; further, each second optical splitter may split each second local oscillator light into a third local oscillator light and a fourth local oscillator light, and each second optical splitter may transmit the third local oscillator light to one input port of the frequency mixer 1 of each echo optical path and may transmit the fourth local oscillator light to one input port of the frequency mixer 2 of each echo optical path. The first local oscillator light transmitted by the single-mode coupler may be an optical signal in a TE0 mode, each second local oscillator light coming out after passing through the first optical splitter is also an optical signal in a TE0 mode, and the third local oscillator light and the fourth local oscillator light coming out after passing through each second optical splitter are still optical signals in a TE0 mode. In the echo optical path, the processing procedure of the first echo light and the processing procedures of the third local oscillator light and the fourth local oscillator light may specifically refer to the processing procedure in fig. 2, and are not described herein again.

The embodiment of the application relates to a light beam receiving device capable of receiving echo signals by multiple channels, wherein local oscillator light input in each echo light path is input after two times of light splitting processing by adopting a first light splitter and a second light splitter, and an implementation mode that one echo light path corresponds to one single-mode coupler is not adopted, but the number of the single-mode couplers is reduced, and the first light splitter and the second light splitter can be integrated on a chip, so that the coupling loss and the area of the chip can be reduced, the influence of a walk-off effect on a receiving system can be reduced, the distance measuring capability of the receiving system is improved, and meanwhile, the integration level of a silicon-based optoelectronic integrated chip can be increased.

Referring to fig. 4, a schematic diagram of a light beam receiving apparatus provided in an embodiment of the present application is shown, where the light beam receiving apparatus includes a local oscillation optical path and an echo optical path, the echo optical path includes two mixers and two balanced detectors, and a mode conversion apparatus in the echo optical path includes a few-mode coupler, a mode demultiplexer, and a mode converter for explanation.

As shown in fig. 4, the optical beam receiving apparatus of the embodiment of the present application may include a single-mode coupler, a polarization rotating beam splitter, a few-mode coupler, a mode demultiplexer, a mode converter, a mixer 1, a mixer 2, a balanced detector 1, and a balanced detector 2.

In fig. 4, for the local oscillation optical path, an input port of the polarization rotation beam splitter is connected to the single-mode coupler, and two output ports of the polarization rotation beam splitter are respectively connected to an input port of the mixer 1 and an input port of the mixer 2; for the echo optical path, the connection relationship between the devices can be referred to the description in fig. 2, and is not described in detail here.

It can be understood that, in the local oscillator optical path, a non-polarization-maintaining fiber may be used to couple the first local oscillator light into the single-mode coupler, and the single-mode coupler may transmit the first local oscillator light to the polarization rotation beam splitter. Further, inside the polarization rotation beam splitter, first, the first local oscillator light may be divided into two orthogonal local oscillator lights in a linear polarization state, one of which may be a local oscillator light in a TE0 mode, that is, a local oscillator light in a transverse electric mode, which may be referred to as a second local oscillator light for convenience of description, and the other may be a local oscillator light in a TM0 mode, that is, a local oscillator light in a transverse magnetic mode, which may be referred to as a third local oscillator light for convenience of description; then, the TM0 mode local oscillation light may be converted into the TE0 mode local oscillation light, that is, the third local oscillation light may be converted into the fourth local oscillation light; the second local oscillator light may then be transmitted to an input port of mixer 1 in the echo optical path, and the fourth local oscillator light may be transmitted to an input port of mixer 2 in the echo optical path.

In the echo optical path, the processing procedure of the first echo light and the processing procedures of the second local oscillator light and the fourth local oscillator light may specifically refer to the processing procedure in fig. 2, which is not described herein again.

In this embodiment, on the one hand, a non-polarization-maintaining optical fiber is adopted in a local oscillation optical path to couple local oscillation light to a single-mode coupler, and then the single-mode coupler transmits the local oscillation light to a polarization rotation beam splitter, because the non-polarization-maintaining optical fiber can transmit random polarized light, unlike a polarization-maintaining optical fiber which can only transmit polarized light in a certain direction, after the local oscillation light passes through the polarization rotation beam splitter, the local oscillation light in other polarization states (local oscillation light in TM0 mode) can be converted into local oscillation light in TE0 mode. Therefore, the non-polarization-maintaining optical fiber is adopted, and the polarization rotation beam splitter is adopted for matching use subsequently, so that the cost of the optical fiber can be saved. On the other hand, a few-mode coupler is adopted in the echo light path to receive echo signals, and due to the characteristic that the receiving end face of the few-mode coupler is large, more echo signals can be received under the condition that a walk-off effect exists, namely the receiving efficiency of the echo signals can be improved; then, the optical signal in TE1 mode in the echo signal is converted into the optical signal in TE0 mode by using the mode converter, although there is conversion loss, the loss is small, and subsequently when the frequency mixer performs beat frequency, because the local oscillator light and the echo light are both in fundamental mode, a better beat frequency effect can be achieved. That is to say, the embodiment of the present application has the advantage of converting the polarization state in the local oscillation optical path, and meanwhile, in the echo optical path, because the receiving end face of the few-mode coupler is larger, the receiving efficiency of the echo signal can be improved, and the processing of the base-mode signal is replaced with smaller mode conversion loss on the chip, so that the utilization rate of the received echo signal can be improved, and further, the embodiment of the present application can reduce the influence of the walk-off effect on the receiving system, and can improve the ranging capability of the receiving system. In addition, the embodiment of the application also has higher integration level and design flexibility, and the size and the cost of the receiving system can be reduced while the distance measurement capability of the receiving system is improved.

Please refer to fig. 5, which is a schematic diagram of a light beam receiving apparatus according to an embodiment of the present disclosure, and the following explains that the light beam receiving apparatus includes one local oscillation optical path and multiple echo optical paths, each echo optical path includes two mixers and two balanced detectors, and a mode conversion apparatus in the echo optical path includes a few-mode coupler, a mode demultiplexer, and a mode converter.

As shown in fig. 5, in the optical beam receiving apparatus according to the embodiment of the present invention, each of the echo optical paths may include a few-mode coupler, a mode demultiplexer, a mode converter, a mixer 1, a mixer 2, a balanced detector 1, and a balanced detector 2. The local oscillation optical path may include a single-mode coupler, one optical splitter, and a plurality of polarization rotation beam splitters, where the number of the polarization rotation beam splitters is equal to the number of the echo optical paths, and fig. 5 shows 2 echo optical paths and 2 polarization rotation beam splitters for illustration.

In fig. 5, for the local oscillation optical path, the single-mode coupler is connected to the input port of the optical splitter, each output port of the optical splitter is connected to the input port of each polarization rotation beam splitter, and the output port of each polarization rotation beam splitter is connected to the input port of the frequency mixer 1 in the echo optical path and the input port of the frequency mixer 2 in the echo optical path; for the echo optical path, the connection relationship between the devices can be referred to the description in fig. 5, and is not described in detail here.

It can be understood that, in the local oscillator optical path, a non-polarization-maintaining optical fiber may be used to couple the first local oscillator light into the single-mode coupler, and the single-mode coupler may transmit the first local oscillator light to the optical splitter. Further, the optical splitter can carry out optical splitting processing on the first local oscillation light to obtain a plurality of second local oscillation lights, and the optical splitter can transmit each second local oscillation light to each polarization rotation beam splitter respectively. Further, inside the polarization rotation beam splitter, first, the second local oscillation light may be divided into a third local oscillation light and a fourth local oscillation light, the third local oscillation light may be an optical signal in a TM0 mode, the fourth local oscillation light may be an optical signal in a TE0 mode, and then the third local oscillation light may be converted into an optical signal in a TE0 mode, so as to obtain a fifth local oscillation light, and then the fifth local oscillation light may be transmitted to an input port of the mixer 1 in the echo optical path corresponding to the current polarization rotation beam splitter, and the fourth local oscillation light may be transmitted to an input port of the mixer 2 in the echo optical path corresponding to the current polarization rotation beam splitter. The first local oscillator light transmitted by the single-mode coupler may be local oscillator light in a random polarization state, and inside the polarization rotation beam splitter, the local oscillator light in the first local oscillator light in different polarization states may be subjected to beam splitting processing, and then one path of optical signal in a TM0 mode and one path of optical signal in a TE0 mode may be obtained, and then the optical signal in the TM0 mode may be converted into an optical signal in a TE0 mode and transmitted to an echo signal. In the echo optical path, the processing procedure of the first echo light and the processing procedures of the fifth local oscillator light and the fourth local oscillator light may specifically refer to the processing procedure in fig. 2, and are not described herein again.

The embodiment of the application is a light beam receiving device capable of receiving echo signals by multiple channels, local oscillator light input in each echo light path is subjected to primary light splitting processing by adopting a light splitter and then is input after being subjected to beam splitting and mode conversion processing by a polarization rotation beam splitter, and an implementation mode that one echo light path corresponds to one single-mode coupler is not adopted, so that the number of the single-mode couplers is reduced, and the light splitter and the polarization rotation beam splitter in the local oscillator light path can be integrated on a chip.

Referring to fig. 6, a schematic diagram of a light beam receiving apparatus provided in an embodiment of the present application is shown, where the light beam receiving apparatus includes a local oscillation optical path and an echo optical path, the echo optical path includes four mixers and four balanced detectors, and a mode conversion apparatus in the echo optical path includes a few-mode coupler, a mode demultiplexer, and a mode converter for explanation.

As shown in fig. 6, the optical beam receiving apparatus according to the embodiment of the present application may include a single-mode coupler, a beam splitter, a few-mode coupler, a mode demultiplexer, a mode converter, a mixer 1, a mixer 2, a mixer 3, a mixer 4, a balanced detector 1, a balanced detector 2, a balanced detector 3, and a balanced detector 4.

In fig. 6, for the local oscillation optical path, the input port of the optical splitter is connected to the single-mode coupler, and the four output ports of the optical splitter are respectively connected to one input port of the mixer 1, one input port of the mixer 2, one input port of the mixer 3, and one input port of the mixer 4; for an echo optical path, the few-mode coupler is connected with an input port of the mode demultiplexer, an output port of the mode demultiplexer is connected with an input port of the mode converter, four output ports of the mode converter are respectively connected with another input port of the mixer 1, another input port of the mixer 2, another input port of the mixer 3 and another input port of the mixer 4, an output port of the mixer 1 is connected with the balanced detector 1, an output port of the mixer 2 is connected with the balanced detector 2, an output port of the mixer 3 is connected with the balanced detector 3, and an output port of the mixer 4 is connected with the balanced detector 4.

It can be understood that, in the local oscillator light path, can adopt polarization maintaining fiber to couple first local oscillator light to single mode coupler, single mode coupler can transmit first local oscillator light to the beam splitter, and is further, the beam splitter can carry out beam splitting processing to first local oscillator light, obtains four second local oscillator light, the beam splitter can transmit four second local oscillator light respectively to an input port of mixer 1, an input port of mixer 2, an input port of mixer 3 and an input port of mixer 4 in the echo light path. Because the polarization maintaining fiber can only transmit polarized light in a certain polarization state, the first local oscillator light transmitted by the single-mode coupler may be an optical signal in the TE0 mode, and the four second local oscillator lights coming out after passing through the optical splitter are still optical signals in the TE0 mode.

In the echo optical path, a few-mode fiber may be selected to couple the first echo light to at least one mode coupler, where the few-mode fiber may specifically be a two-mode fiber, a three-mode fiber, a four-mode fiber, and the like, and at this time, the first echo light may include optical signals in TE mode and TM mode, and the few-mode coupler may transmit the first echo light including the modes to the mode demultiplexer. Further, inside the mode demultiplexer, the first echo light including the TM mode and the TE mode may be divided into four different optical paths for transmission, one optical path may transmit an optical signal of the TE0 mode, one optical path may transmit an optical signal of the TE1 mode, one optical path may transmit an optical signal of the TM0 mode, and another optical path may transmit an optical signal of the TM1 mode, for convenience of description, the optical signal of the TE0 mode may be referred to as second echo light, the optical signal of the TE1 mode may be referred to as third echo light, the optical signal of the TM0 mode may be referred to as fourth echo light, and the optical signal of the TM1 mode may be referred to as fifth echo light, and then, the mode demultiplexer may transmit the second echo light, the third echo light, the fourth echo light, and the fifth echo light to four different input ports of the mode converter respectively. Further, the mode converter may convert the third echo light, i.e., the optical signal in TE1 mode, into the optical signal in TE0 mode, and for convenience of description, the optical signal after the conversion of the third echo light may be referred to as a sixth echo light; similarly, the mode converter may convert the fourth echo light, i.e. the optical signal in the TM0 mode, into the optical signal in the TE0 mode, so as to obtain a seventh echo light; similarly, the mode converter may further convert the fifth echo light, i.e. the optical signal in TM1 mode, into the optical signal in TE0 mode, so as to obtain the eighth echo light. Then, the mode converter may transmit the second echo light to another input port of the mixer 1, may transmit the sixth echo light to another input port of the mixer 2, may transmit the seventh echo light to another input port of the mixer 3, and may transmit the eighth echo light to another input port of the mixer 4. Further, the mixer 1 may receive a second local oscillation light and a second echo light, where both the two optical signals are optical signals in the TE0 mode; similarly, the mixer 2 may receive the third local oscillation light and the sixth echo light, where both of the two optical signals are optical signals in the TE0 mode; similarly, the mixer 3 may receive the fourth local oscillation light and the seventh echo light, where both of the two optical signals are optical signals in the TE0 mode; similarly, the mixer 4 may receive the four-five local oscillation light and the eighth echo light, which are both optical signals in the TE0 mode. Further, after each mixer performs frequency mixing processing on the local oscillation light and the echo light in the TE0 mode, the frequency mixed light obtained by the frequency mixing is transmitted to a balance detector corresponding to each mixer, the balance detector converts the frequency mixed light into an electrical signal, and the electrical signal is correspondingly processed to obtain detection information of a detection target, where the detection information may include values of parameters such as distance, speed, azimuth, height, and attitude. Specifically, the detection information of the detection target is obtained according to the electrical signal, the distance and the speed can be mainly obtained according to the electrical signal, and further, the corresponding data processing is performed on the speed and the distance, so that the values of the parameters such as the azimuth, the altitude, the attitude and the like can be obtained.

When the scheme of the embodiment of the application is executed, the few-mode coupler is adopted to receive the echo signal, because the mode field of the few-mode coupler is large, under the condition that the walk-off effect exists, more echo signals can be received, that is, the receiving efficiency of the echo signal can be improved, then, the mode demultiplexer and the mode converter can collect all the energy of the optical signal coupled into the few-mode coupler, not only can transmit the optical signal in the TE mode and the optical signal in the TM mode, but also can convert the optical signal in the TM mode into the optical signal in the TE mode, then transmit the optical signal in the TE mode to the mixer for beat frequency processing, and then transmit the optical signal obtained by beat frequency processing to the balance detector for subsequent signal processing, so that the utilization rate of the received echo signal can be improved. Therefore, the embodiment of the application can receive echo signals in different polarization states, then convert the optical signal of the transverse magnetic mode into the optical signal of the transverse electric mode, and convert the non-fundamental mode into the fundamental mode, so that the utilization rate of the received echo signals can be improved, the influence of the walk-off effect on a receiving system can be reduced, and the distance measurement capability of the receiving system can be improved. In addition, the embodiment of the application also has higher integration level and design flexibility, and the size and the cost of the receiving system can be reduced while the distance measurement capability of the receiving system is improved.

Referring to fig. 7, a schematic diagram of a light beam receiving apparatus provided in an embodiment of the present application is shown, where the light beam receiving apparatus includes one local oscillation optical path and multiple echo optical paths, each echo optical path includes four mixers and four balanced detectors, and a mode conversion apparatus in the echo optical path includes a few-mode coupler, a mode demultiplexer, and a mode converter for explanation.

As shown in fig. 7, the optical beam receiving apparatus according to the embodiment of the present application may include a single-mode coupler, a first optical splitter, a second optical splitter, a few-mode coupler, a mode demultiplexer, a mode converter, a mixer 1, a mixer 2, a mixer 3, a mixer 4, a balanced detector 1, a balanced detector 2, a balanced detector 3, and a balanced detector 4. In fig. 7, the number of the second optical splitters is equal to the number of the echo optical paths, and the embodiment of the present application shows 2 echo optical paths and 2 second optical splitters for illustration.

In fig. 7, for the local oscillation optical path, an input port of a first optical splitter is connected to a single-mode coupler, an output port of the first optical splitter is connected to an input port of each second optical splitter, and four output ports of each second optical splitter are connected to an input port of a mixer 1, an input port of a mixer 2, an input port of a mixer 3, and an input port of a mixer 4 in the echo optical path, where the number of the second optical splitters is equal to the number of paths of the echo optical path. For each echo optical path, the few-mode coupler is connected with an input port of the mode demultiplexer, an output port of the mode demultiplexer is connected with an input port of the mode converter, four output ports of the mode converter are respectively connected with another input port of the mixer 1, another input port of the mixer 2, another input port of the mixer 3 and another input port of the mixer 4, an output port of the mixer 1 is connected with the balanced detector 1, an output port of the mixer 2 is connected with the balanced detector 2, an output port of the mixer 3 is connected with the balanced detector 3, and an output port of the mixer 4 is connected with the balanced detector 4.

It can be understood that, in the local oscillator optical path, the polarization maintaining fiber may be adopted to couple the first local oscillator light into the single-mode coupler, and the single-mode coupler may transmit the first local oscillator light to the first optical splitter. Further, the first optical splitter may perform optical splitting processing on the first local oscillator light to obtain a plurality of second local oscillator lights, and the first optical splitter may transmit each of the second local oscillator lights to each of the second optical splitters, respectively. Further, the second optical splitter may perform optical splitting processing on the second local oscillator light to obtain a third local oscillator light, a fourth local oscillator light, a fifth local oscillator light, and a sixth local oscillator light, transmit the third local oscillator light to an input port of the mixer 1 in each echo optical path, transmit the fourth local oscillator light to an input port of the mixer 2 in each echo optical path, transmit the fifth local oscillator light to an input port of the mixer 3 in each echo optical path, and transmit the sixth local oscillator light to an input port of the mixer 4 in each echo optical path. In the echo optical path, the processing procedure of the first echo light, and the processing procedures of the third local oscillator light, the fourth local oscillator light, the fifth local oscillator light, and the sixth local oscillator light may specifically refer to the processing procedure in fig. 6, and are not described herein again.

The embodiment of the application is a light beam receiving device capable of receiving echo signals by multiple channels, wherein local oscillator light input in each echo light path is obtained after two times of light splitting processing by using a first light splitter and a second light splitter, and an implementation mode that one echo light path corresponds to one single-mode coupler is not adopted, but the number of the single-mode couplers is reduced, and the single-mode couplers, the first light splitter and the second light splitter in the local oscillator light path can be integrated on a chip.

It should be noted that, in the foregoing embodiments, receiving local oscillator light in different polarization states and receiving echo light in different polarization states are respectively implemented, and in some embodiments, polarization diversity reception of local oscillator light and polarization diversity reception of echo light may be implemented simultaneously.

Further, an embodiment of the present application further provides a light beam receiving method, please refer to fig. 8, which is a schematic flow chart of the light beam receiving method according to the embodiment of the present application, where the light beam receiving method is applied to a light beam receiving device, the light beam receiving device includes one local oscillator light path and at least one echo light path, and each echo light path includes a mode conversion device, at least two frequency mixers, and a balance detector corresponding to each frequency mixer; the local oscillator optical path is respectively connected with the at least two frequency mixers; the mode conversion device is respectively connected with the at least two mixers; each mixer is connected to each balanced detector.

S801, dividing the first local oscillation light into at least two second local oscillation lights by the local oscillation light path, and respectively transmitting each second local oscillation light to each echo light path.

In some embodiments, when the optical beam receiving apparatus includes one local oscillation optical path and one echo optical path, the local oscillation optical path may include a single-mode coupler and an optical splitter; the echo optical path may include a few-mode coupler, a mode demultiplexer, a mode converter, a first mixer, a first balanced detector corresponding to the first mixer, a second mixer, and a second balanced detector corresponding to the second mixer. The connection relationship between the above devices can be seen in the schematic diagram shown in fig. 2, and is not described herein again.

It can be understood that, in the local oscillator light path, can adopt polarization maintaining fiber to couple first local oscillator light to single mode coupler, single mode coupler can transmit first local oscillator light to the beam splitter, and further, the beam splitter can carry out beam splitting processing to first local oscillator light, obtains two second local oscillator light, and the beam splitter can transmit two second local oscillator light respectively to an input port of first mixer (mixer 1), an input port of second mixer (mixer 2) of echo light path. The first local oscillator light transmitted by the single-mode coupler may be an optical signal in a TE0 mode, and the two second local oscillator lights coming out after passing through the optical splitter are still optical signals in a TE0 mode.

In some embodiments, when the optical beam receiving apparatus includes one local oscillation optical path and multiple echo optical paths, each echo optical path may include an few-mode coupler, a mode demultiplexer, a mode converter, a first mixer, a first balanced detector corresponding to the first mixer, a second mixer, and a second balanced detector corresponding to the second mixer; the local oscillation optical path may include a single-mode coupler, a first optical splitter, and at least two second optical splitters, where the number of the second optical splitters is equal to the number of the echo optical paths. The connection relationship between the above devices can be seen in the schematic diagram shown in fig. 3, and is not described herein again.

It can be understood that, in the local oscillator optical path, a polarization maintaining fiber may be adopted to couple the first local oscillator light into the single mode coupler, and the single mode coupler may transmit the first local oscillator light to the first optical splitter; further, the first optical splitter may perform optical splitting processing on the first local oscillator light to obtain a plurality of second local oscillator lights, and the first optical splitter may transmit each of the second local oscillator lights to each of the second optical splitters respectively; furthermore, each second optical splitter may split each second local oscillator light into a third local oscillator light and a fourth local oscillator light, and each second optical splitter may transmit the third local oscillator light to an input port of the first frequency mixer (frequency mixer 1) of each echo optical path, and may transmit the fourth local oscillator light to an input port of the second frequency mixer (frequency mixer 2) of each echo optical path. The first local oscillator light transmitted by the single-mode coupler may be an optical signal in a TE0 mode, each second local oscillator light coming out after passing through the first optical splitter is also an optical signal in a TE0 mode, and the third local oscillator light and the fourth local oscillator light coming out after passing through each second optical splitter are still optical signals in a TE0 mode.

In some embodiments, when the optical beam receiving apparatus includes a local oscillation optical path and a return optical path, the return optical path includes an few-mode coupler, a mode demultiplexer, a mode converter, a first mixer, a first balanced detector corresponding to the first mixer, a second mixer, and a second balanced detector corresponding to the second mixer; the local oscillation optical path comprises a single-mode coupler and a polarization rotation beam splitter. The connection relationship between the above devices can be seen in the schematic diagram shown in fig. 4, and is not described herein again.

It can be understood that, in the local oscillator optical path, a non-polarization-maintaining fiber may be used to couple the first local oscillator light to the single-mode coupler, and the single-mode coupler may transmit the first local oscillator light to the polarization rotation beam splitter. Further, inside the polarization rotation beam splitter, first, the first local oscillation light may be divided into two orthogonal local oscillation lights in a linear polarization state, that is, one local oscillation light may be in a TE0 mode, and for convenience of description, may be referred to as a second local oscillation light, and the other local oscillation light may be in a TM0 mode, and for convenience of description, may be referred to as a third local oscillation light; then, the TM0 mode local oscillation light may be converted into the TE0 mode local oscillation light, that is, the third local oscillation light may be converted into the fourth mode local oscillation light; the second local oscillator light may then be transmitted to an input port of the first mixer (mixer 1) in the echo optical path, and the fourth local oscillator light may be transmitted to an input port of the second mixer (mixer 2) in the echo optical path. Therefore, the local oscillator light is coupled to the single-mode coupler by the non-polarization-maintaining fiber, and then is transmitted to the polarization rotation beam splitter by the single-mode coupler, because the non-polarization-maintaining fiber can transmit random polarized light, unlike the polarization-maintaining fiber which can only transmit polarized light in a certain direction, after passing through the polarization rotation beam splitter, the local oscillator light in other polarization states (local oscillator light in a TM0 mode) can be converted into local oscillator light in a TE0 mode. Therefore, the non-polarization-maintaining optical fiber is adopted, and the polarization rotation beam splitter is adopted for matching use subsequently, so that the cost of the optical fiber can be saved.

In some embodiments, when the optical beam receiving apparatus includes one local oscillation optical path and multiple echo optical paths, each echo optical path includes an few-mode coupler, a mode demultiplexer, a mode converter, a first mixer, a first balanced detector corresponding to the first mixer, a second mixer, and a second balanced detector corresponding to the second mixer; the local oscillation optical path comprises a beam splitter and at least two polarization rotation beam splitters, and the number of the polarization rotation beam splitters is equal to that of the echo optical paths. The connection relationship between the above devices can be seen in the schematic diagram shown in fig. 5, and is not described herein again.

It can be understood that, in the local oscillator optical path, a non-polarization-maintaining optical fiber may be used to couple the first local oscillator light into the single-mode coupler, and the single-mode coupler may transmit the first local oscillator light to the optical splitter. Further, the optical splitter can carry out optical splitting processing on the first local oscillation light to obtain a plurality of second local oscillation lights, and the optical splitter can transmit each second local oscillation light to each polarization rotation beam splitter respectively. Further, inside the polarization rotation beam splitter, the second local oscillation light may be first divided into a third local oscillation light and a fourth local oscillation light, the third local oscillation light may be an optical signal in a TM0 mode, the fourth local oscillation light may be an optical signal in a TE0 mode, the third local oscillation light may be converted into an optical signal in a TE0 mode, a fifth local oscillation light is obtained, the fifth local oscillation light may be transmitted to an input port of the first mixer (mixer 1) in the echo optical path corresponding to the current polarization rotation beam splitter, and the fourth local oscillation light may be transmitted to an input port of the second mixer (mixer 2) in the echo optical path corresponding to the current polarization rotation beam splitter. The first local oscillator light transmitted by the single-mode coupler may be local oscillator light in a random polarization state, and inside the polarization rotation beam splitter, the local oscillator light in the first local oscillator light in different polarization states may be subjected to beam splitting processing, and then one path of optical signal in a TM0 mode and one path of optical signal in a TE0 mode may be obtained, and then the optical signal in the TM0 mode may be converted into an optical signal in a TE0 mode and transmitted to an echo signal. Therefore, the implementation mode that one echo optical path corresponds to one single-mode coupler is not adopted, the number of the single-mode couplers is reduced, the optical splitter and the polarization rotation optical splitter in the local oscillation optical path can be integrated on a chip, and the coupling loss and the chip area can be reduced.

In some embodiments, when the optical beam receiving apparatus includes a local oscillation optical path and a return optical path, the return optical path may include a few-mode coupler, a mode demultiplexer, a mode converter, a first mixer, a first balanced detector corresponding to the first mixer, a second balanced detector corresponding to the second mixer, a third balanced detector corresponding to the third mixer, a fourth mixer, and a fourth balanced detector corresponding to the fourth mixer; the local oscillator optical path may include a single mode coupler and an optical splitter. The connection relationship between the above devices can be seen in the schematic diagram shown in fig. 6, and is not described herein again.

It can be understood that, in the local oscillator optical path, a polarization maintaining fiber may be adopted to couple the first local oscillator light to the single mode coupler, the single mode coupler may transmit the first local oscillator light to the optical splitter, further, the optical splitter may perform optical splitting processing on the first local oscillator light to obtain four second local oscillator lights, and the optical splitter may transmit the four second local oscillator lights to an input port of the first mixer (mixer 1), an input port of the second mixer (mixer 2), an input port of the third mixer (mixer 3), and an input port of the fourth mixer (mixer 4) in the echo optical path, respectively. Because the polarization maintaining fiber can only transmit polarized light in a certain polarization state, the first local oscillator light transmitted by the single-mode coupler may be an optical signal in the TE0 mode, and the four second local oscillator lights coming out after passing through the optical splitter are still optical signals in the TE0 mode.

In some embodiments, when the optical beam receiving apparatus includes one local oscillation optical path and multiple echo optical paths, each echo optical path includes a few-mode coupler, a mode demultiplexer, a mode converter, a first mixer, a first balanced detector corresponding to the first mixer, a second balanced detector corresponding to the second mixer, a third balanced detector corresponding to the third mixer, a fourth mixer, and a fourth balanced detector corresponding to the fourth mixer; the local oscillator optical path comprises a single-mode coupler, a first optical splitter and at least two second optical splitters, and the number of the second optical splitters is equal to that of the echo optical paths. The connection relationship between the above devices can be seen in the schematic diagram shown in fig. 7, and is not described herein again.

It can be understood that, in the local oscillator optical path, the polarization maintaining fiber may be adopted to couple the first local oscillator light into the single-mode coupler, and the single-mode coupler may transmit the first local oscillator light to the first optical splitter. Further, the first optical splitter may perform optical splitting processing on the first local oscillator light to obtain a plurality of second local oscillator lights, and the first optical splitter may transmit each of the second local oscillator lights to each of the second optical splitters, respectively. Further, the second optical splitter may perform optical splitting processing on the second local oscillator light to obtain a third local oscillator light, a fourth local oscillator light, a fifth local oscillator light, and a sixth local oscillator light, transmit the third local oscillator light to an input port of the first mixer (mixer 1) in each echo optical path, transmit the fourth local oscillator light to an input port of the second mixer (mixer 2) in each echo optical path, transmit the fifth local oscillator light to an input port of the third mixer (mixer 3) in each echo optical path, and transmit the sixth local oscillator light to an input port of the fourth mixer (mixer 4) in each echo optical path. Therefore, the implementation mode that one echo optical path corresponds to one single-mode coupler is not adopted, the number of the single-mode couplers is reduced, the single-mode coupler, the first optical splitter and the second optical splitter in the local oscillation optical path can be integrated on a chip, and the coupling loss and the chip area can be reduced.

S802, each path of echo light path converts each first echo light into at least two second echo lights in a preset mode, and at least two pieces of detection information of a detection target are determined based on each second echo light and each second local oscillator light.

In some embodiments, for the optical beam receiving apparatus shown in fig. 2, in the echo optical path, the few-mode optical fiber may be selected to couple the first echo light into at least one mode coupler, where the few-mode optical fiber may specifically be a two-mode optical fiber, a three-mode optical fiber, a four-mode optical fiber, and so on, in which case, the first echo light may include optical signals in TE0 mode and TE1 mode, and the few-mode coupler may transmit the first echo light including the two modes to the mode demultiplexer; inside the mode demultiplexer, the two modes of optical signals contained in the first echo light may be divided into two optical signals transmitted by different optical paths, one optical path may transmit an optical signal of a TE0 mode, and the other optical path may transmit an optical signal of a TE1 mode, for convenience of description, the optical signal of the TE0 mode may be referred to as a second echo light, and the optical signal of the TE1 mode may be referred to as a third echo light, and then, the mode demultiplexer may transmit the second echo light and the third echo light to two different input ports of the mode converter respectively; further, the mode converter may convert the third echo light, i.e. the optical signal in TE1 mode, into the optical signal in TE0 mode, and for convenience of description, the optical signal after the conversion of the third echo light may be referred to as a fourth echo light, and in this case, the fourth echo light and the second echo light are both the optical signal in TE0 mode; further, the mode converter may transmit the second echo light and the fourth echo light to another input port of the mixer 1 and another input port of the mixer 2, respectively; further, the frequency mixer 1 may receive second echo light and second local oscillator light, both of which are optical signals in the TE0 mode, and meanwhile, the frequency mixer 2 may also receive fourth echo light and second local oscillator light, both of which are optical signals in the TE0 mode, and the two frequency mixers may perform frequency mixing processing on a base mode and then transmit the optical signals after frequency mixing to the balanced detector; further, the balance detector may convert the mixed light into an electrical signal, and perform corresponding processing on the electrical signal to obtain detection information of the detection target, where the detection information may include values of parameters such as distance, speed, azimuth, altitude, and attitude. Specifically, the detection information of the detection target is obtained according to the electrical signal, the distance and the speed can be mainly obtained according to the electrical signal, and further, the corresponding data processing is performed on the speed and the distance, so that the values of the parameters such as the azimuth, the altitude, the attitude and the like can be obtained. According to the embodiment of the application, the few-mode coupler is adopted to receive echo signals, because the mode field of the few-mode coupler is large, more echo signals can be received under the condition that a walk-off effect exists, then, the optical signals in a TE1 mode in the echo signals are converted into the optical signals in a TE0 mode by the mode converter, although conversion loss exists, the loss is small, when the frequency mixer conducts beat frequency, because local oscillator light and echo light are the optical signals in the same mode, a better beat frequency effect can be achieved, namely, more echo signals can be received, most of energy in the echo signals can be received, then subsequent signal processing is conducted, the influence of the walk-off effect on a receiving system can be reduced, and the distance measuring capability of the receiving system can be improved.

In some embodiments, for the light beam receiving apparatus shown in fig. 3, 4, and 5, in the echo optical path, the processing process of the optical signal may specifically refer to the processing process in fig. 2, and is not described herein again.

In some embodiments, for the optical beam receiving apparatus shown in fig. 6, in the echo optical path, the few-mode optical fiber may be selected to couple the first echo light into at least one mode coupler, and the few-mode optical fiber may be specifically a two-mode optical fiber, a three-mode optical fiber, a four-mode optical fiber, and the like. Further, inside the mode demultiplexer, the first echo light including the TM mode and the TE mode may be divided into four different optical paths for transmission, one optical path may transmit an optical signal of the TE0 mode, one optical path may transmit an optical signal of the TE1 mode, one optical path may transmit an optical signal of the TM0 mode, and another optical path may transmit an optical signal of the TM1 mode, for convenience of description, the optical signal of the TE0 mode may be referred to as second echo light, the optical signal of the TE1 mode may be referred to as third echo light, the optical signal of the TM0 mode may be referred to as fourth echo light, and the optical signal of the TM1 mode may be referred to as fifth echo light, and then, the mode demultiplexer may transmit the second echo light, the third echo light, the fourth echo light, and the fifth echo light to four different input ports of the mode converter respectively. Further, the mode converter may convert the third echo light, i.e., the optical signal in TE1 mode, into the optical signal in TE0 mode, and for convenience of description, the optical signal after the conversion of the third echo light may be referred to as a sixth echo light; similarly, the mode converter may convert the fourth echo light, i.e. the optical signal in the TM0 mode, into the optical signal in the TE0 mode, so as to obtain a seventh echo light; similarly, the mode converter may further convert the fifth echo light, i.e. the optical signal in TM1 mode, into the optical signal in TE0 mode, so as to obtain the eighth echo light. Then, the mode converter may transmit the second echo light to another input port of the mixer 1, may transmit the sixth echo light to another input port of the mixer 2, may transmit the seventh echo light to another input port of the mixer 3, and may transmit the eighth echo light to another input port of the mixer 4. Further, the mixer 1 may receive a second local oscillation light and a second echo light, where both the two optical signals are optical signals in the TE0 mode; similarly, the mixer 2 may receive the third local oscillation light and the sixth echo light, where both of the two optical signals are optical signals in the TE0 mode; similarly, the mixer 3 may receive the fourth local oscillation light and the seventh echo light, where both of the two optical signals are optical signals in the TE0 mode; similarly, the mixer 4 may receive the four-five local oscillation light and the eighth echo light, which are both optical signals in the TE0 mode. Further, after each mixer performs frequency mixing processing on the local oscillation light and the echo light in the TE0 mode, the frequency mixed light obtained by the frequency mixing is transmitted to a balance detector corresponding to each mixer, the balance detector converts the frequency mixed light into an electrical signal, and the electrical signal is correspondingly processed to obtain detection information of a detection target, where the detection information may include values of parameters such as distance, speed, azimuth, height, and attitude. Specifically, the detection information of the detection target is obtained according to the electrical signal, the distance and the speed can be mainly obtained according to the electrical signal, and further, the corresponding data processing is performed on the speed and the distance, so that the values of the parameters such as the azimuth, the altitude, the attitude and the like can be obtained. The mode demultiplexer and the mode converter adopted in the embodiment of the application can collect all the energy of the optical signals coupled into the few-mode coupler, not only can transmit the optical signals in the TE mode and the TM mode, but also can convert the optical signals in the TM mode into the optical signals in the TE mode, and then transmit the optical signals in the TE mode to the mixer for beat frequency processing.

In some embodiments, for the light beam receiving apparatus shown in fig. 7, in the echo optical path, the processing process of the optical signal may specifically refer to the processing process in fig. 6, and is not described herein again.

The embodiment of the application is not only suitable for the light beam receiving device for receiving the echo signal in a single channel, but also suitable for the light beam receiving device for receiving the echo signal in multiple channels, and polarization diversity reception of the echo signal can be realized no matter in the single channel or in the multiple channels. In addition, the method and the device can convert non-fundamental mode signals in the received echo signals into fundamental mode signals with small mode conversion loss, can perform beat frequency processing on the local oscillator light and the echo light in the fundamental mode form in the frequency mixer, and can achieve a good beat frequency effect. Therefore, the embodiment of the application not only realizes the polarization diversity reception of the echo signals, but also utilizes the characteristic that the receiving end surface of the few-mode coupler is larger, can improve the receiving efficiency of the echo signals, can also improve the utilization rate of the received echo signals on a chip, can further reduce the influence of the walk-off effect on a receiving system, and can improve the distance measuring capability of the receiving system. Moreover, when the multi-channel receiving echo signal is realized, the use number of single-mode couplers can be reduced, the coupling loss and the chip area can be further reduced, and the integration level of a silicon-based optoelectronic integrated chip can be increased on the basis of improving the ranging capability, so that the receiving system has better design flexibility, and the size and the cost of the receiving system can be reduced.

It should be noted that, in the above method embodiment, polarization diversity reception of the local oscillator light is described in S801, and polarization diversity reception of the echo light is described in S802, and in some embodiments, polarization diversity reception of the local oscillator light and polarization diversity reception of the echo light may be simultaneously implemented, which is not limited in this application, and a specific implementation manner may refer to polarization diversity reception in the above description.

The above description is intended only to illustrate the alternative embodiments of the present application, and should not be construed as limiting the present application, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A light beam receiving device is characterized by comprising a local oscillator light path and at least one echo light path, wherein each echo light path comprises a mode conversion device, at least two frequency mixers and a balance detector corresponding to each frequency mixer; wherein:

2. The optical beam receiving device according to claim 1, wherein the mode converting device comprises an few-mode coupler, a mode demultiplexer, and a mode converter, wherein output ports of the few-mode coupler are connected to input ports of the mode demultiplexer, and output ports of the mode demultiplexer are connected to input ports of the mode converter;

each echo light path is used for transmitting each first echo light and converting each first echo light into at least two second echo lights in a preset mode, and the method comprises the following steps:

in each echo light path, each few-mode coupler is used for transmitting each first echo light to each mode demultiplexer;

in each echo light path, each mode demultiplexer is configured to convert each first echo light into echo light in at least two different modes;

in each echo optical path, each mode converter is configured to convert the echo light in the at least two different modes into at least two second echo lights in a preset mode.

3. The optical beam receiving device according to claim 2, wherein when the optical beam receiving device includes an echo optical path, the echo optical path includes an few-mode coupler, a mode demultiplexer, a mode converter, a first mixer, a first balanced detector corresponding to the first mixer, a second mixer, and a second balanced detector corresponding to the second mixer; the local oscillator optical path comprises a single-mode coupler and an optical splitter; wherein:

a first input port of the first mixer is connected to a first output port of the mode converter, a second input port of the first mixer is connected to a first output port of the optical splitter, and an output port of the first mixer is connected to the first balanced detector;

a first input port of the second mixer is connected to a second output port of the mode converter, a second input port of the second mixer is connected to a second output port of the optical splitter, and an output port of the second mixer is connected to the second balanced detector;

a first input port of the mode converter is connected with a first output port of the mode demultiplexer, and a second input port of the mode converter is connected with a second output port of the mode demultiplexer;

the single-mode coupler is connected with the input port of the optical splitter.

4. The optical beam receiving device according to claim 3, wherein the single-mode coupler is configured to transmit the first local oscillator light to the optical splitter;

the optical splitter is configured to split the first local oscillator light into a second local oscillator light and a third local oscillator light, transmit the second local oscillator light to the first frequency mixer, and transmit the third local oscillator light to the second frequency mixer; the second local oscillator light and the third local oscillator light are optical signals in the same mode;

the mode demultiplexer is configured to convert the first echo light into second echo light and third echo light, and transmit the second echo light and the third echo light to the mode converter, where the second echo light and the third echo light are optical signals in different modes;

the mode converter is configured to convert the third echo light into fourth echo light, transmit the second echo light to the first mixer, and transmit the fourth echo light to the second mixer, where the fourth echo light and the second echo light are optical signals in the same mode;

the first frequency mixer is configured to perform frequency mixing processing on the second local oscillator light and the second echo light to obtain first mixed light, and transmit the first mixed light to the first balanced detector;

the second frequency mixer is configured to perform frequency mixing processing on the third local oscillation light and the fourth echo light to obtain second mixed light, and transmit the second mixed light to the second balanced detector;

the first balance detector obtains first detection information based on the first mixing light;

and the second balanced detector obtains second detection information based on the second mixing light.

5. The optical beam receiving apparatus according to claim 2, wherein when the optical beam receiving apparatus includes at least two echo optical paths, each echo optical path includes a few-mode coupler, a mode demultiplexer, a mode converter, a first mixer, a first balanced detector corresponding to the first mixer, a second mixer, and a second balanced detector corresponding to the second mixer; the local oscillator optical path comprises a single-mode coupler, a first optical splitter and at least two second optical splitters, and the number of the second optical splitters is equal to the number of the echo optical paths; wherein:

in each echo optical path, a first input port of the first mixer is connected to a first output port of the mode converter, a second input port of the first mixer is connected to a first output port of the second optical splitter, and an output port of the first mixer is connected to the first balanced detector;

in each echo optical path, a first input port of the second mixer is connected to a second output port of the mode converter, a second input port of the second mixer is connected to a second output port of the second optical splitter, and an output port of the second mixer is connected to the second balanced detector;

in each echo signal, a first input port of the mode converter is connected with a first output port of the mode demultiplexer, and a second input port of the mode converter is connected with a second output port of the mode demultiplexer;

the first optical splitter comprises an input port and at least two output ports, the input port of the first optical splitter is connected with the single-mode coupler, each output port of the first optical splitter is respectively connected with the input port of each second optical splitter, and the number of the output ports of the first optical splitter is equal to that of the second optical splitters.

6. The optical beam receiving apparatus according to claim 5, wherein the single-mode coupler is configured to transmit a first local oscillator light to the first optical splitter;

the first optical splitter is configured to split the first local oscillator light into at least two second local oscillator lights, and transmit each second local oscillator light to each second optical splitter, where the number of the second optical splitters is equal to the number of the second local oscillator lights;

each second optical splitter is configured to split each second local oscillator light into a third local oscillator light and a fourth local oscillator light, transmit the third local oscillator light to the first frequency mixer in each echo optical path, and transmit the fourth local oscillator light to the second frequency mixer in each echo optical path; the third local oscillator light and the fourth local oscillator light are optical signals in the same mode;

in each echo light path, the few-mode coupler is used for transmitting each first echo light to each mode demultiplexer;

the each mode demultiplexer is configured to convert each first echo light into a second echo light and a third echo light, and transmit the second echo light and the third echo light to each mode converter, where the second echo light and the third echo light are optical signals in different modes;

each mode converter is configured to convert the third echo light into fourth echo light, transmit the second echo light to each first mixer, and transmit the fourth echo light to each second mixer, where the fourth echo light and the second echo light are optical signals in the same mode;

each first frequency mixer is configured to perform frequency mixing processing on the third local oscillator light and the second echo light to obtain each first mixed light, and transmit each first mixed light to each first balanced detector;

each second frequency mixer is configured to perform frequency mixing processing on the fourth local oscillation light and the fourth echo light to obtain each second mixed light, and transmit each second mixed light to each second balanced detector;

each first balanced detector obtains each first detection information based on each first mixing light;

each second balanced detector obtains each second detection information based on each second mixed light.

7. The optical beam receiving apparatus according to claim 2, wherein when the optical beam receiving apparatus includes one echo optical path, the echo optical path includes an few-mode coupler, a mode demultiplexer, a mode converter, a first mixer, a first balanced detector corresponding to the first mixer, a second mixer, and a second balanced detector corresponding to the second mixer; the local oscillation optical path comprises a single-mode coupler and a polarization rotation beam splitter; wherein:

a first input port of the first mixer is connected to a first output port of the mode converter, a second input port of the first mixer is connected to a first output port of the polarization rotating beam splitter, and an output port of the first mixer is connected to the first balanced detector;

a first input port of the second mixer is connected to a second output port of the mode converter, a second input port of the second mixer is connected to a second output port of the polarization rotating beam splitter, and an output port of the second mixer is connected to the second balanced detector;

the single-mode coupler is connected with the input port of the polarization rotation beam splitter.

8. The optical beam receiving device of claim 7, wherein the single-mode coupler is configured to transmit the first local oscillator light to the polarization rotating beam splitter;

the polarization rotation beam splitter is configured to split the first local oscillation light into a second local oscillation light and a third local oscillation light, convert the third local oscillation light into a fourth local oscillation light, transmit the second local oscillation light to the first frequency mixer, and transmit the fourth local oscillation light to the second frequency mixer; the second local oscillator light and the third local oscillator light are optical signals of different modes, and the second local oscillator light and the fourth local oscillator light are optical signals of the same mode;

the second frequency mixer is configured to perform frequency mixing processing on the fourth local oscillation light and the fourth echo light to obtain second mixed light, and transmit the second mixed light to the second balanced detector;

9. The optical beam receiving apparatus according to claim 2, wherein when the optical beam receiving apparatus includes at least two echo optical paths, each echo optical path includes a few-mode coupler, a mode demultiplexer, a mode converter, a first mixer, a first balanced detector corresponding to the first mixer, a second mixer, and a second balanced detector corresponding to the second mixer; the local oscillation optical path comprises a light splitter and at least two polarization rotation beam splitters, and the number of the polarization rotation beam splitters is equal to that of the echo optical paths; wherein:

in each echo optical path, a first input port of the first mixer is connected to a first output port of the mode converter, a second input port of the first mixer is connected to a first output port of each polarization rotation beam splitter, and an output port of the first mixer is connected to the first balanced detector;

in each echo optical path, a first input port of the second mixer is connected to a second output port of the mode converter, a second input port of the second mixer is connected to a second output port of each polarization rotation beam splitter, and an output port of the second mixer is connected to the second balanced detector;

the optical splitter comprises an input port and at least two output ports, the input port of the optical splitter is connected with the single-mode coupler, each output port of the optical splitter is respectively connected with the input port of each polarization rotation beam splitter, and the number of the output ports of the first optical splitter is equal to that of the polarization rotation beam splitters.

10. The optical beam receiving device according to claim 9, wherein the single-mode coupler is configured to transmit the first local oscillator light to the optical splitter;

the optical splitter is configured to split the first local oscillation light into at least two second local oscillation lights, and transmit each second local oscillation light to each polarization rotation beam splitter, where the number of the polarization rotation beam splitters is equal to the number of the second local oscillation lights;

each polarization rotation beam splitter is configured to split the second local oscillator light into a third local oscillator light and a fourth local oscillator light, convert the third local oscillator light into a fifth local oscillator light, transmit the fifth local oscillator light to the first frequency mixer in each echo optical path, and transmit the fourth local oscillator light to the second frequency mixer in each echo optical path; the third local oscillator light and the fourth local oscillator light are optical signals in different modes; the fifth local oscillator light and the fourth local oscillator light are optical signals in the same mode;

each mode demultiplexer is configured to convert each first echo light into a second echo light and a third echo light, and transmit the second echo light and the third echo light to each mode converter, where the second echo light and the third echo light are optical signals in different modes;

each first frequency mixer is configured to perform frequency mixing processing on the fifth local oscillator light and the second echo light to obtain each first mixed light, and transmit each first mixed light to each first balanced detector;

11. The optical beam receiving apparatus according to claim 2, wherein when the optical beam receiving apparatus includes a return optical path, the return optical path includes a few-mode coupler, a mode demultiplexer, a mode converter, a first mixer, a first balanced detector corresponding to the first mixer, a second balanced detector corresponding to the second mixer, a third balanced detector corresponding to the third mixer, a fourth mixer, and a fourth balanced detector corresponding to the fourth mixer; the local oscillator optical path comprises a single-mode coupler and an optical splitter; wherein:

a first input port of the first mixer is connected with a first output port of the mode converter, a second input port of the first mixer is connected with a first output port of the optical splitter, and an output port of the first mixer is connected with the first balanced detector;

a first input port of the third mixer is connected with a third output port of the mode converter, a second input port of the third mixer is connected with a third output port of the optical splitter, and an output port of the third mixer is connected with the third balanced detector;

a first input port of the fourth mixer is connected to a fourth output port of the mode converter, a second input port of the fourth mixer is connected to a fourth output port of the optical splitter, and an output port of the fourth mixer is connected to the fourth balanced detector;

a first input port of the mode converter is connected with a first output port of the mode demultiplexer, a second input port of the mode converter is connected with a second output port of the mode demultiplexer, a third input port of the mode converter is connected with a third output port of the mode demultiplexer, and a fourth input port of the mode converter is connected with a fourth output port of the mode demultiplexer;

12. The optical beam receiving device according to claim 11, wherein the single-mode coupler is configured to transmit the first local oscillator light to the optical splitter;

the optical splitter is configured to split the first local oscillator light into a second local oscillator light, a third local oscillator light, a fourth local oscillator light, and a fifth local oscillator light, transmit the second local oscillator light to the first mixer, transmit the third local oscillator light to the second mixer, transmit the fourth local oscillator light to the third mixer, and transmit the fifth local oscillator light to the fourth mixer; the second local oscillator light, the third local oscillator light, the fourth local oscillator light and the fifth local oscillator light are optical signals in the same mode;

the mode demultiplexer is configured to convert the first echo light into second, third, fourth, and fifth echo light, and transmit the second, third, fourth, and fifth echo light to the mode converter, where the second, third, fourth, and fifth echo light are optical signals in different modes;

the mode converter is configured to convert the third echo light into sixth echo light, convert the fourth echo light into seventh echo light, convert the fifth echo light into eighth echo light, and transmit the second echo light to the first mixer, the sixth echo light being transmitted to the second mixer, the seventh echo light being transmitted to the third mixer, and the eighth echo light being transmitted to the fourth mixer, where the second echo light, the sixth echo light, the seventh echo light, and the eighth echo light are optical signals in the same mode;

the second frequency mixer is configured to perform frequency mixing processing on the third local oscillation light and the sixth echo light to obtain second mixed light, and transmit the second mixed light to the second balanced detector;

the third mixer is configured to perform frequency mixing processing on the fourth local oscillation light and the seventh echo light to obtain third mixed light, and transmit the third mixed light to the third balanced detector;

the fourth frequency mixer is configured to perform frequency mixing processing on the fifth local oscillation light and the eighth echo light to obtain fourth mixed light, and transmit the fourth mixed light to the fourth balanced detector;

the second balanced detector obtains second detection information based on the second mixing light;

the third balanced detector obtains third detection information based on the third mixed light;

and the fourth balanced detector obtains fourth detection information based on the fourth mixed light.

13. The optical beam receiving apparatus according to claim 2, wherein when the optical beam receiving apparatus includes at least two echo optical paths, each echo optical path includes a few-mode coupler, a mode demultiplexer, a mode converter, a first mixer, a first balanced detector corresponding to the first mixer, a second balanced detector corresponding to the second mixer, a third balanced detector corresponding to the third mixer, a fourth mixer, and a fourth balanced detector corresponding to the fourth mixer; the local oscillator optical path comprises a single-mode coupler, a first optical splitter and at least two second optical splitters, and the number of the second optical splitters is equal to that of the echo optical paths; wherein:

in each echo optical path, a first input port of the first mixer is connected to a first output port of the mode converter, a second input port of the first mixer is connected to a first output port of each second optical splitter, and an output port of the first mixer is connected to the first balanced detector;

in each echo optical path, a first input port of the second mixer is connected to a second output port of the mode converter, a second input port of the second mixer is connected to a second output port of each second optical splitter, and an output port of the second mixer is connected to the second balanced detector;

in each echo optical path, a first input port of the third mixer is connected to a third output port of the mode converter, a second input port of the third mixer is connected to a third output port of each second optical splitter, and an output port of the third mixer is connected to the third balanced detector;

in each echo optical path, a first input port of the fourth mixer is connected to a fourth output port of the mode converter, a second input port of the fourth mixer is connected to a fourth output port of each second optical splitter, and an output port of the fourth mixer is connected to the fourth balanced detector;

in each echo signal, a first input port of the mode converter is connected with a first output port of the mode demultiplexer, a second input port of the mode converter is connected with a second output port of the mode demultiplexer, a third input port of the mode converter is connected with a third output port of the mode demultiplexer, and a fourth input port of the mode converter is connected with a fourth output port of the mode demultiplexer;

14. The optical beam receiving device of claim 13, wherein the single-mode coupler is configured to transmit a first local oscillator light to the first optical splitter;

the first optical splitter is configured to split the first local oscillator light into at least two second local oscillator lights, and transmit each second local oscillator light to each second optical splitter, where the number of the second optical splitters is equal to that of the second local oscillator lights;

each second optical splitter is configured to split the second local oscillator light into a third local oscillator light, a fourth local oscillator light, a fifth local oscillator light, and a sixth local oscillator light, transmit the third local oscillator light to the first frequency mixer in each echo optical path, transmit the fourth local oscillator light to the second frequency mixer in each echo optical path, transmit the fifth local oscillator light to the third frequency mixer in each echo optical path, and transmit the sixth local oscillator light to the fourth frequency mixer in each echo optical path; the third local oscillator light, the fourth local oscillator light, the fifth local oscillator light and the sixth local oscillator light are optical signals in the same mode;

each mode demultiplexer is configured to convert each first echo light into a second echo light, a third echo light, a fourth echo light, and a fifth echo light, and transmit the second echo light, the third echo light, the fourth echo light, and the fifth echo light to each mode converter, where the second echo light, the third echo light, the fourth echo light, and the fifth echo light are optical signals in different modes respectively;

each mode converter is configured to convert the third echo light into sixth echo light, convert the fourth echo light into seventh echo light, convert the fifth echo light into eighth echo light, and transmit the second echo light to each first mixer, transmit the fourth sixth echo light to each second mixer, transmit the seventh echo light to each third mixer, and transmit the eighth echo light to each fourth mixer, where the second echo light, the sixth echo light, the seventh echo light, and the eighth echo light are optical signals in the same mode;

each second frequency mixer is configured to perform frequency mixing processing on the fourth local oscillation light and the sixth echo light to obtain each second mixed light, and transmit each second mixed light to each second balanced detector;

each third mixer is configured to perform frequency mixing processing on the fifth local oscillator light and the seventh echo light to obtain each third mixed light, and transmit each third mixed light to each third balanced detector;

each fourth frequency mixer is configured to perform frequency mixing processing on the sixth local oscillator light and the eighth echo light to obtain each fourth mixed light, and transmit each fourth mixed light to each fourth balanced detector;

each second balanced detector obtains each second detection information based on each second mixing light;

each third balanced detector obtains each third detection information based on each third mixing light;

and each fourth balanced detector obtains each fourth detection information based on each fourth mixed light.

15. A light beam receiving method is applied to a light beam receiving device, wherein the light beam receiving device comprises a local oscillator light path and at least one echo light path, and each echo light path comprises a mode conversion device, at least two frequency mixers and a balance detector corresponding to each frequency mixer; the local oscillator optical path is respectively connected with the at least two frequency mixers; the mode conversion device is respectively connected with the at least two mixers; each mixer connected to each balanced detector, the method comprising:

16. The method according to claim 15, wherein the mode conversion apparatus comprises an few-mode coupler, a mode demultiplexer, and a mode converter, the few-mode coupler is connected to the input port of the mode demultiplexer, and the output port of the mode demultiplexer is connected to the input port of the mode converter;

each first echo light is converted into at least two second echo lights in a preset mode by each echo light path, and the method comprises the following steps:

in each echo light path, the few-mode coupler transmits each first echo light to the mode demultiplexer, the mode demultiplexer converts each first echo light into at least two echo lights in different modes, and the mode converter converts the at least two echo lights in different modes into at least two second echo lights in a preset mode.

17. The method of claim 16, wherein when the optical beam receiving device includes N echo optical paths, where N is an integer greater than or equal to 1, each echo optical path includes a few-mode coupler, a mode demultiplexer, a mode converter, a first mixer, a first balanced detector corresponding to the first mixer, a second mixer, and a second balanced detector corresponding to the second mixer;

when N is 1, the local oscillator light path includes single mode coupler and optical splitter, the local oscillator light path is divided into two at least second local oscillator light with first local oscillator light, and with every second local oscillator light transmits respectively to every way echo light path, includes:

the single-mode coupler transmits the first local oscillator light to the optical splitter;

the optical splitter splits the first local oscillator light into second local oscillator light and third local oscillator light, transmits the second local oscillator light to the first frequency mixer, and transmits the third local oscillator light to the second frequency mixer; the second local oscillator light and the third local oscillator light are optical signals in the same mode;

when N is for being greater than 1 integer, the local oscillator light path includes single mode coupler, first optical splitter and N second optical splitter, the local oscillator light path divides first local oscillator light into two at least second local oscillator light, and with every second local oscillator light transmits respectively to every way echo light path includes:

the single-mode coupler transmits first local oscillator light to the first optical splitter;

the first optical splitter splits the first local oscillator light into N fourth local oscillator lights, and transmits each fourth local oscillator light to each second optical splitter;

each second optical splitter splits each fourth local oscillator light into a second local oscillator light and a third local oscillator light, transmits the second local oscillator light to the first frequency mixer, and transmits the third local oscillator light to the second frequency mixer; the second local oscillator light and the third local oscillator light are optical signals in the same mode;

each path of echo optical path is used for transmitting each first echo light, converting each first echo light into at least two second echo lights in a preset mode, and determining at least two detection information of a detection target based on each second echo light and each second local oscillator light, including:

in each echo light path, the few-mode coupler transmits first echo light to the mode demultiplexer;

the mode demultiplexer converts the first echo light into second echo light and third echo light, and transmits the second echo light and the third echo light to the mode converter, where the second echo light and the third echo light are optical signals in different modes;

18. The method of claim 16, wherein when the optical beam receiving device includes N echo optical paths, where N is an integer greater than or equal to 1, each echo optical path includes a few-mode coupler, a mode demultiplexer, a mode converter, a first mixer, a first balanced detector corresponding to the first mixer, a second mixer, and a second balanced detector corresponding to the second mixer;

when N is 1, the local oscillator light path includes single mode coupler and rotatory beam splitter of polarization, the local oscillator light path is divided into two at least second local oscillator light with first local oscillator light, and will every second local oscillator light transmits respectively extremely every way echo light path includes:

the single-mode coupler transmits the first local oscillator light to the polarization rotation beam splitter;

the polarization rotation beam splitter divides the first local oscillation light into second local oscillation light and third local oscillation light, converts the third local oscillation light into fourth local oscillation light, transmits the second local oscillation light to the first frequency mixer, and transmits the fourth local oscillation light to the second frequency mixer; the second local oscillator light and the third local oscillator light are optical signals of different modes, and the second local oscillator light and the fourth local oscillator light are optical signals of the same mode;

when N is for being greater than 1 integer, the local oscillator light path includes single mode coupler, optical splitter and a rotatory beam splitter of N polarization, the local oscillator light path is divided into two at least second local oscillator light with first local oscillator light, and with every second local oscillator light transmits respectively to every way echo light path includes:

the optical splitter divides the first local oscillation light into N fifth local oscillation lights and transmits each fifth local oscillation light to each polarization rotation beam splitter;

each polarization rotation beam splitter divides each fifth local oscillator light into a second local oscillator light and a third local oscillator light, converts the third local oscillator light into a fourth local oscillator light, transmits the second local oscillator light to the first frequency mixer, and transmits the fourth local oscillator light to the second frequency mixer; the second local oscillator light and the third local oscillator light are optical signals of different modes, and the second local oscillator light and the fourth local oscillator light are optical signals of the same mode;

each echo light path is used for transmitting each first echo light, converting each first echo light into at least two second echo lights in a preset mode, and determining at least two detection information of a detection target based on each second echo light and each second local oscillator light, and the method comprises the following steps:

the mode converter converts the third echo light into fourth echo light, transmits the second echo light to the first mixer, and transmits the fourth echo light to the second mixer, wherein the fourth echo light and the second echo light are optical signals in the same mode;

the first frequency mixer performs frequency mixing processing on the second local oscillation light and the second echo light to obtain first mixed light, and transmits the first mixed light to the first balanced detector;

the second frequency mixer performs frequency mixing processing on the fourth local oscillation light and the fourth echo light to obtain second mixed light, and transmits the second mixed light to the second balanced detector;

19. The method of claim 16, wherein when the optical beam receiving device includes N echo optical paths, where N is an integer greater than or equal to 1, each echo optical path includes a few-mode coupler, a mode demultiplexer, a mode converter, a first mixer, a first balanced detector corresponding to the first mixer, a second balanced detector corresponding to the second mixer, a third balanced detector corresponding to the third mixer, a fourth mixer, and a fourth balanced detector corresponding to the fourth mixer;

when N is 1, the local oscillator light path includes single mode coupler and optical splitter, the local oscillator light path is divided into two at least second local oscillator light with first local oscillator light, and with every second local oscillator light transmits respectively extremely every way echo light path includes:

the optical splitter splits the first local oscillator light into second local oscillator light, third local oscillator light, fourth local oscillator light and fifth local oscillator light, transmits the second local oscillator light to the first mixer, transmits the third local oscillator light to the second mixer, transmits the fourth local oscillator light to the third mixer, and transmits the fifth local oscillator light to the fourth mixer; the second local oscillator light, the third local oscillator light, the fourth local oscillator light and the fifth local oscillator light are optical signals in the same mode;

the first optical splitter splits the first local oscillator light into N sixth local oscillator light, and transmits each sixth local oscillator light to each second optical splitter;

each second optical splitter splits each sixth local oscillator light into a second local oscillator light, a third local oscillator light, a fourth local oscillator light and a fifth local oscillator light, transmits the second local oscillator light to the first frequency mixer, transmits the third local oscillator light to the second frequency mixer, transmits the fourth local oscillator light to the third frequency mixer, and transmits the fifth local oscillator light to the fourth frequency mixer; the second local oscillator light, the third local oscillator light, the fourth local oscillator light and the fifth local oscillator light are optical signals in the same mode;

the mode demultiplexer converts the first echo light into second echo light, third echo light, fourth echo light and fifth echo light, and transmits the second echo light, the third echo light, the fourth echo light and the fifth echo light to the mode converter, wherein the second echo light, the third echo light, the fourth echo light and the fifth echo light are optical signals in different modes respectively;

the mode converter converts the third echo light into sixth echo light, converts the fourth echo light into seventh echo light, converts the fifth echo light into eighth echo light, and transmits the second echo light to the first mixer, the sixth echo light is transmitted to the second mixer, the seventh echo light is transmitted to the third mixer, and the eighth echo light is transmitted to the fourth mixer, the second echo light, the sixth echo light, the seventh echo light, and the eighth echo light are optical signals of the same mode;

the second frequency mixer performs frequency mixing processing on the third local oscillation light and the sixth echo light to obtain second mixed light, and transmits the second mixed light to the second balanced detector;

the third mixer performs frequency mixing processing on the fourth local oscillation light and the seventh echo light to obtain third mixed light, and transmits the third mixed light to the third balanced detector;

the fourth frequency mixer performs frequency mixing processing on the fifth local oscillation light and the eighth echo light to obtain fourth mixed light, and transmits the fourth mixed light to the fourth balanced detector;