Light beam receiving device and light beam receiving method

Abstract

The embodiment of the present application discloses a light beam receiving device and a light beam receiving method, wherein the light beam receiving device includes a local oscillator optical path and at least one echo optical path, each echo optical path includes a mode conversion device, at least two mixers, and a balanced detector corresponding to each mixer, the local oscillator optical path is connected to each mixer, the mode conversion device is connected to each mixer, and each mixer is respectively connected to a balanced detector corresponding to each mixer. The embodiment of the present application utilizes the echo optical path to transmit a first echo light, converts the first echo light into at least two second echo lights of a preset mode, and determines multiple detection information of a detection target based on the second echo light and the second local oscillator light, which can improve the utilization rate of the received echo signal in exchange for a very small mode conversion loss, thereby reducing the influence of the walk-off effect on the receiving system, and improving the ranging capability of the receiving system.

Description

Technical Field

[0001] The present application relates to the field of laser radar technology, and in particular to a light beam receiving device and a light beam receiving method. Background Art

[0002] Frequency modulated continuous wave laser radar has the advantages of strong anti-interference ability, high ranging accuracy, and easy integration. It has developed rapidly and is widely used. Laser radar has a variety of scanning structures, such as galvanometer, rotating mirror, prism, etc., which can be used as scanning structures. In the coaxial system of the above scanning structure, there will be different time differences between the transmitted light beam and the reflected echo light beam due to the different target distances, resulting in the echo light beam reaching the surface of the galvanometer or rotating mirror. The galvanometer or rotating mirror has already rotated a certain angle. At this time, when the echo light beam enters the receiving lens, there is a certain angle offset compared to the transmitted light beam, which causes the focus point after passing through the lens to be offset. Usually, the farther the distance, the greater the offset of the focus point. This phenomenon is called the walk-off effect. Summary of the invention

[0003] The embodiment of the present application provides a light beam receiving device and a light beam receiving method, which can convert a non-fundamental mode signal in a received echo signal into a fundamental mode signal for transmission with very small conversion loss, thereby improving the utilization rate of the received echo signal, thereby reducing the influence of the walk-off effect on the receiving system, and improving the ranging capability of the receiving system. The technical solution is as follows:

[0004] In a first aspect, an embodiment of the present application provides a light beam receiving device, comprising a local oscillator optical path and at least one echo optical path, each echo optical path comprising a mode conversion device, at least two mixers, and a balanced detector corresponding to each mixer, the local oscillator optical path is connected to each mixer, the mode conversion device is connected to each mixer, and each mixer is respectively connected to the balanced detector corresponding to each mixer; wherein:

[0005] The local oscillator optical path is used to transmit a first local oscillator light, and to split the first local oscillator light into at least two second local oscillator lights, and to transmit each of the second local oscillator lights to each of the echo optical paths;

[0006] Each echo light path is used to transmit each first echo light, and to convert each first echo light into at least two second echo lights of a preset mode, and to determine at least two detection information of a detection target based on each second echo light and each second local oscillation light.

[0007] 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, wherein the light beam receiving device includes a local oscillator optical path and at least one echo optical path, each echo optical path includes a mode conversion device, at least two mixers, and a balanced detector corresponding to each mixer; the local oscillator optical path is respectively connected to the at least two mixers; the mode conversion device is respectively connected to the at least two mixers; each mixer is connected to each balanced detector; characterized in that the method includes:

[0008] The local oscillator optical path divides the first local oscillator light into at least two second local oscillator lights, and transmits each of the second local oscillator lights to each of the echo optical paths respectively;

[0009] Each echo light path converts each first echo light into at least two second echo lights of a preset mode, and determines at least two detection information of the detection target based on each second echo light and each second local oscillation light.

[0010] The beneficial effects brought by the technical solution provided by the embodiment of the present application include at least:

[0011] When the scheme of the embodiment of the present application is executed, it is applied to a light beam receiving device, the light beam receiving device includes a local oscillator optical path and at least one echo optical path, each echo optical path includes a mode conversion device, at least two mixers and a balanced detector corresponding to each mixer, the local oscillator optical path is connected to each mixer, the mode conversion device is connected to each mixer, and each mixer is respectively connected to the balanced detector corresponding to each mixer. Based on the above devices, the embodiment of the present application uses the echo optical path to transmit the first echo light, converts the first echo light into at least two second echo lights of a preset mode, and determines at least two detection information of the detection target based on each second echo light and each second local oscillator light transmitted by the local oscillator optical path, so that the non-fundamental mode signal in the received echo signal can be converted into the fundamental mode for transmission with very small conversion loss, so that most of the energy of the echo signal can be received, and the utilization rate of the received echo signal can be improved, so that the influence of the walk-off effect on the receiving system can be reduced, and the ranging capability of the receiving system can be improved. In addition, the embodiments of the present application also support multi-path echo optical paths, and are compatible with polarization diversity reception and multi-channel splicing, thereby increasing the integration of silicon-based optoelectronic integrated chips and reducing the size and cost of the receiving system. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0013] Figure 1 is a schematic diagram of a light beam receiving device provided in an embodiment of the present application;

[0014] Figure 2 is a schematic diagram of another light beam receiving device provided in an embodiment of the present application;

[0015] Figure 3 is a schematic diagram of another light beam receiving device provided in an embodiment of the present application;

[0016] Figure 4 is a schematic diagram of another light beam receiving device provided in an embodiment of the present application;

[0017] Figure 5 is a schematic diagram of another light beam receiving device provided in an embodiment of the present application;

[0018] Figure 6 is a schematic diagram of another light beam receiving device provided in an embodiment of the present application;

[0019] Figure 7 is a schematic diagram of another light beam receiving device provided in an embodiment of the present application;

[0020] Figure 8 It is a flow chart of a light beam receiving method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0021] In order to make the purpose, 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 in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0022] In the description of the present application, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. In the description of the present application, it should be noted that, unless otherwise clearly specified and limited, "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood in specific circumstances. In addition, in the description of the present application, unless otherwise specified, "multiple" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects before and after are an "or" relationship.

[0023] In the related technology, when the walk-off effect exists, the reflected echo signal has a certain position offset relative to the transmitted signal when it is received, and it is difficult to couple well into the single-mode optical fiber, resulting in serious loss of the reflected echo signal, causing the receiving end to receive the echo signal at a reduced rate, limiting the coupling efficiency of the optical fiber at the receiving end, and thus affecting the ranging capability of the lidar system.

[0024] In order to more clearly describe the technical solution of the embodiment of the present application, before the description, some concepts in the present application are described in detail for a better understanding of the solution.

[0025] TE0 mode may refer to the fundamental mode of the transverse electric mode in which the electric field direction is perpendicular to the propagation direction.

[0026] TE1 mode may refer to a non-fundamental transverse electric mode in which the electric field direction is perpendicular to the propagation direction.

[0027] The TM0 mode may refer to the fundamental mode of the transverse magnetic mode in which the magnetic field direction is perpendicular to the propagation direction.

[0028] The TM1 mode may refer to a non-fundamental transverse magnetic mode in which the magnetic field direction is perpendicular to the propagation direction.

[0029] The present application is described in detail below with reference to specific embodiments.

[0030] See also Figure 1 , is a schematic diagram of a light beam receiving device provided in an embodiment of the present application. The light beam receiving device includes a local oscillator optical path and an echo optical path, and the echo optical path includes two mixers and two balanced detectors for explanation below.

[0031] like Figure 1 As shown, the light beam receiving device of the embodiment of the present application may include: a local oscillator optical path and an echo optical path. The echo optical path includes a mode conversion device, a mixer 1, a balanced detector 1, a mixer 2, and a balanced detector 2.

[0032] exist Figure 1 In the embodiment, the two output ports of the local oscillator optical path are respectively connected to an input port of mixer 1 and an input port of mixer 2, the two output ports of the mode conversion device in the echo optical path are respectively connected to another input port of mixer 1 and another input port of mixer 2, the output port of mixer 1 is connected to the input port of balanced detector 1, and the output port of mixer 2 is connected to the input port of balanced detector 2.

[0033] Based on the connection relationship between the above components, the principles of the embodiments of the present application are explained below.

[0034] It can be understood that the first local oscillation light can be transmitted in the local oscillation light path, the local oscillation light path can split the first local oscillation light into two second local oscillation lights, and both local oscillation lights are transmitted to the mixer in the echo light path. Specifically, the first local oscillation light can be received by a single-mode coupler in the local oscillation light path, and then the first local oscillation light can be split into two second local oscillation lights by an optical splitter.

[0035] The first echo light can be transmitted in the echo light path. Inside the mode conversion device, the first echo light can be converted into two different modes of echo light, one of which can be a fundamental mode echo light, and the other echo light can be a non-fundamental mode echo light. Further, the non-fundamental mode echo light can be converted into a fundamental mode echo light. Further, the mode conversion device can transmit the two fundamental mode echo lights, that is, the two second echo lights, to two mixers respectively. Further, inside the mixer, the mixer can mix the second echo light and the local oscillator light to obtain mixed light, and the mixer can also transmit the mixed light to the balanced detector. Further, the balanced detector can convert the mixed light into an electrical signal, and the detection information of the detection target can be obtained by correspondingly processing the electrical signal. The detection information can include the values ​​of parameters such as distance, speed, azimuth, altitude, and attitude. Specifically, the detection information of the detection target can be obtained according to the electrical signal, mainly the distance and speed can be obtained according to the electrical signal. Further, the speed and distance are processed accordingly to obtain the values ​​of parameters such as azimuth, altitude, and attitude.

[0036] When the scheme of the embodiment of the present application is executed, the mode conversion device can convert the light of different modes in the echo light into the light of preset mode, mainly converting the non-fundamental mode light into the fundamental mode light. Because the local oscillator light path usually transmits the local oscillator light of the fundamental mode, when the local oscillator light transmitted by the local oscillator light path and the echo light transmitted by the echo light path are beat in the mixer, the beat of the light of the same mode can achieve a better beat effect. That is to say, the non-fundamental mode signal in the received echo signal can be converted into the fundamental mode signal for transmission with very small conversion loss, thereby improving the utilization rate of the received echo signal, thereby reducing the influence of the walk-off effect on the receiving system, and improving the ranging capability of the receiving system.

[0037] See also Figure 2 , is a schematic diagram of a light beam receiving device provided in an embodiment of the present application. The light beam receiving device includes a local oscillator light path and an echo light path, and the echo light path includes two mixers and two balanced detectors, and the mode conversion device in the echo light path includes a few-mode coupler, a mode demultiplexer, and a mode converter for explanation below.

[0038] like Figure 2 As shown, the optical beam receiving device of the embodiment of the present application may include a single-mode coupler, a 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.

[0039] exist Figure 2 In the figure, for the local oscillator optical path, the input port of the splitter is connected to the single-mode coupler, and the two output ports of the splitter are respectively connected to an input port of mixer 1 and an input port of mixer 2; for the echo optical path, the few-mode coupler is connected to the input port of the mode demultiplexer, the two output ports of the mode demultiplexer are connected to the two input ports of the mode converter, the two output ports of the mode converter are respectively connected to the other input port of mixer 1 and the other input port of mixer 2, the two output ports of mixer 1 are connected to balanced detector 1, and the two output ports of mixer 2 are connected to balanced detector 2.

[0040] Based on the connection relationship between the above components, the principles of the embodiments of the present application are explained below.

[0041] It can be understood that, in the local oscillator optical path, a polarization-maintaining optical fiber can be used to couple the first local oscillator light to a single-mode coupler, and the single-mode coupler can transmit the first local oscillator light to an optical splitter. Further, the optical splitter can split the first local oscillator light to obtain two second local oscillator lights, and the optical splitter can transmit the two second local oscillator lights to an input port of mixer 1 and an input port of mixer 2 of the echo optical path, respectively. The first local oscillator light transmitted by the single-mode coupler can be a TE0 mode optical signal, and the two second local oscillator lights that come out of the optical splitter are still TE0 mode optical signals.

[0042] In the echo optical path, a few-mode optical fiber can be selected to couple the first echo light to the at least mode coupler. The few-mode optical fiber can specifically be a two-mode optical fiber. At this time, the first echo light can contain optical signals of TE0 mode and TE1 mode. The few-mode coupler can transmit the first echo light containing the transverse electric mode, fundamental mode and non-fundamental transverse electric mode to the mode demultiplexer; inside the mode demultiplexer, the optical signals of the two modes contained in the first echo light can be divided into optical signals transmitted by two different optical paths, one optical path can transmit the optical signal of TE0 mode, and the other optical path can transmit the optical signal of TE1 mode. For the convenience of description, the optical signal of TE0 mode can be called the second echo light, and the optical signal of TE1 mode can be called the third echo light. Then, the mode demultiplexer can transmit the second echo light and the third echo light to two different input ports of the mode converter respectively; further, the mode converter can convert the third echo light, that is, the optical signal of TE1 mode, into the optical signal of TE0 mode. For the convenience of description, the optical signal after the conversion of the third echo light can be called the fourth echo light. At this time, the fourth echo light and the second echo light are both optical signals in the TE0 mode; further, the mode converter can transmit the second echo light and the fourth echo light to another input port of mixer 1 and another input port of mixer 2 respectively; further, mixer 1 can receive the second echo light and the second local oscillation light, and the second echo light and the second local oscillation light are both optical signals in the TE0 mode. At the same time, mixer 2 can also receive the fourth echo light and the second local oscillation light, and the fourth echo light and the second local oscillation light are also optical signals in the TE0 mode. The two mixers can perform mixing processing on the fundamental mode, and then transmit the optical signal after mixing to the balanced detector; further, the balanced detector can convert the mixed light into an electrical signal, and the detection information of the detected target can be obtained by correspondingly processing the electrical signal. The detection information may include the values ​​of parameters such as distance, speed, azimuth, altitude, and attitude. Specifically, the detection information of the detection target can be obtained based on the electrical signal, mainly the distance and speed can be obtained based on the electrical signal. Further, by performing corresponding data processing on the speed and distance, the values ​​of parameters such as azimuth, altitude, and attitude can be obtained.

[0043] It should be noted that, in other embodiments, the few-mode optical fiber may also be a three-mode, four-mode, five-mode or other few-mode optical fiber, and the present application does not impose any limitation on this.

[0044] When the scheme of the embodiment of the present application is executed, a few-mode coupler is used to receive the echo signal. Since the mode field of the few-mode coupler is large, the reception efficiency of the echo signal can be improved in the presence of the walk-off effect. Then, a mode converter is used to convert the TE1 mode optical signal in the echo signal into a TE0 mode optical signal. Although there is conversion loss, the loss is small. When the mixer is subsequently used for beat frequency, since both the local oscillator light and the echo light are fundamental mode signals, a better beat frequency effect can be achieved. That is to say, the present application can improve the reception efficiency of the echo signal, and can also improve the utilization rate of the received echo signal, thereby reducing the influence of the walk-off effect on the receiving system, and can improve the ranging capability of the receiving system.

[0045] See also Figure 3 , is a schematic diagram of a light beam receiving device provided in an embodiment of the present application. The light beam receiving device includes one local oscillator light path and multiple echo light paths, and each echo light path includes two mixers and two balanced detectors. The mode conversion device in each echo light path includes a few-mode coupler, a mode demultiplexer, and a mode converter for explanation below.

[0046] like Figure 3 As shown, in the optical beam receiving device of the embodiment of the present application, each echo optical path 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 oscillator optical path may include a single-mode coupler, a first optical splitter, and a plurality of second optical splitters, the number of the second optical splitters being equal to the number of the echo optical paths. Figure 3 Two return optical paths and two second optical splitters are shown for illustration.

[0047] exist Figure 3 The connection relationship between the components in each return optical path can be found in Figure 2 For the local oscillator optical path, the single-mode coupler is connected to the input port of the first optical splitter, the multiple output ports of the first optical splitter are respectively connected to the input port of each second optical splitter, the number of the output ports of the first optical splitter is equal to the number of the second optical splitter, and the two output ports of each second optical splitter are respectively connected to an input port of mixer 1 in each echo optical path and an input port of mixer 2 in each echo optical path.

[0048] Based on the connection relationship between the above components, the principles of the embodiments of the present application are explained below.

[0049] It can be understood that, in the local oscillator optical path, a polarization-maintaining optical fiber can be used to couple the first local oscillator light into a single-mode coupler, and the single-mode coupler can transmit the first local oscillator light to the first optical splitter; further, the first optical splitter can perform optical splitting processing on the first local oscillator light to obtain multiple second local oscillator lights, and the first optical splitter can transmit each second local oscillator light to each second optical splitter respectively; further, each second optical splitter can split each second local oscillator light into a third local oscillator light and a fourth local oscillator light, and each second optical splitter can transmit the third local oscillator light to an input port of mixer 1 of each echo optical path, and can transmit the fourth local oscillator light to an input port of mixer 2 of each echo optical path. The first local oscillator light transmitted by the single-mode coupler can be a TE0 mode optical signal, and each second local oscillator light coming out after the first optical splitter is also a TE0 mode optical signal, and the third local oscillator light and the fourth local oscillator light coming out after each second optical splitter are still TE0 mode optical signals. In the echo optical path, the processing of the first echo light, as well as the processing of the third and fourth local oscillation lights, can be found in detail. Figure 2 The processing process in will not be repeated here.

[0050] The embodiment of the present application is a light beam receiving device that can realize multiple channels to receive echo signals. The local oscillator light input into each echo optical path is input after two optical splitting processes using a first optical splitter and a second optical splitter. The implementation method of one single-mode coupler corresponding to one echo optical path is not adopted, but the number of single-mode couplers is reduced, and the first optical splitter and the second optical splitter can be integrated on the chip, thereby reducing coupling loss and chip area, reducing the impact of the walk-off effect on the receiving system, improving the ranging capability of the receiving system, and increasing the integration of the silicon-based optoelectronic integrated chip.

[0051] See also Figure 4 , is a schematic diagram of a light beam receiving device provided in an embodiment of the present application. The light beam receiving device includes a local oscillator light path and an echo light path, and the echo light path includes two mixers and two balanced detectors, and the mode conversion device in the echo light path includes a few-mode coupler, a mode demultiplexer, and a mode converter for explanation below.

[0052] like Figure 4 As shown, the optical beam receiving device of the embodiment of the present application may include a single-mode coupler, a polarization rotation 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.

[0053] exist Figure 4In the example, for the local oscillator optical path, the input port of the polarization rotation beam splitter is connected to the single-mode coupler, and the two output ports of the polarization rotation beam splitter are connected to an input port of mixer 1 and an input port of mixer 2 respectively; for the return optical path, the connection relationship between the components can be seen in Figure 2 The description in will not be repeated here.

[0054] Based on the connection relationship between the above components, the principles of the embodiments of the present application are explained below.

[0055] It can be understood that, in the local oscillator optical path, a non-polarization-maintaining optical fiber can be used to couple the first local oscillator light into a single-mode coupler, and the single-mode coupler can transmit the first local oscillator light to a polarization rotation beam splitter. Further, inside the polarization rotation beam splitter, first, the first local oscillator light can be divided into two local oscillator lights of orthogonal linear polarization states, one of which can be a local oscillator light of the TE0 mode, that is, a local oscillator light of the fundamental mode of the transverse electric mode, which can be referred to as the second local oscillator light for the convenience of description, and the other can be a local oscillator light of the TM0 mode, that is, a local oscillator light of the fundamental mode of the transverse magnetic mode, which can be referred to as the third local oscillator light for the convenience of description; then, the local oscillator light of the TM0 mode can be converted into the local oscillator light of the TE0 mode, that is, the third local oscillator light can be converted into the fourth local oscillator light; then, the second local oscillator light can be transmitted to an input port of mixer 1 in the echo optical path, and the fourth local oscillator light can be transmitted to an input port of mixer 2 in the echo optical path.

[0056] In the echo optical path, the processing of the first echo light, as well as the processing of the second local oscillation light and the fourth local oscillation light, can be found in detail. Figure 2 The processing process in will not be repeated here.

[0057] In the embodiment of the present application, on the one hand, a non-polarization-maintaining optical fiber is used in the local oscillator optical path to couple the local oscillator light to a single-mode coupler, and then the local oscillator light is transmitted to a polarization rotation beam splitter by the single-mode coupler. Since the non-polarization-maintaining optical fiber can transmit random polarized light, unlike the polarization-maintaining optical fiber that can only transmit polarized light in a certain direction, the local oscillator light can be converted into the local oscillator light of the TE0 mode in other polarization states (the local oscillator light of the TM0 mode) after passing through the polarization rotation beam splitter. Therefore, the use of non-polarization-maintaining optical fiber and the subsequent use of the polarization rotation beam splitter can save the cost of optical fiber. On the other hand, a few-mode coupler is used in the echo optical path to receive the echo signal. Due to the large receiving end face of the few-mode coupler, more echo signals can be received in the presence of the walk-off effect, that is, the receiving efficiency of the echo signal can be improved; then, a mode converter is used to convert the optical signal of the TE1 mode in the echo signal into the optical signal of the TE0 mode. Although there is a conversion loss, the loss is small. When the mixer is subsequently beat, since the local oscillator light and the echo light are both fundamental modes, a better beat effect can be achieved. That is to say, the embodiment of the present application has the advantage of converting polarization states in the local oscillator optical path. At the same time, in the echo optical path, the receiving efficiency of the echo signal can be improved due to the large receiving end face of the few-mode coupler, and the processing of the fundamental mode signal in exchange for a smaller mode conversion loss on the chip can improve the utilization rate of the received echo signal. Therefore, the embodiment of the present application can reduce the impact of the walk-off effect on the receiving system and improve the ranging capability of the receiving system. In addition, the embodiment of the present application also has a high degree of integration and design flexibility, and can reduce the volume and cost of the receiving system while improving the ranging capability of the receiving system.

[0058] See also Figure 5 , is a schematic diagram of a light beam receiving device provided in an embodiment of the present application. The light beam receiving device includes one local oscillator light path and multiple echo light paths, and each echo light path includes two mixers and two balanced detectors, and the mode conversion device in the echo light path includes a few-mode coupler, a mode demultiplexer, and a mode converter for explanation below.

[0059] like Figure 5 As shown, in the optical beam receiving device of the embodiment of the present application, each echo optical path may include a few-mode coupler, a mode demultiplexer, a mode converter, mixer 1, mixer 2, balanced detector 1 and balanced detector 2. The local oscillator optical path may include a single-mode coupler, a beam splitter and a plurality of polarization rotation beam splitters, and the number of polarization rotation beam splitters is equal to the number of echo optical paths. Figure 5 Two return optical paths and two polarization rotating beam splitters are shown for illustration.

[0060] exist Figure 5In the LO 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 rotating beam splitter, and each output port of the polarization rotating beam splitter is connected to the input port of mixer 1 in the return optical path and the input port of mixer 2 in the return optical path; for the return optical path, the connection relationship between the components can be seen in Figure 5 The description in will not be repeated here.

[0061] Based on the connection relationship between the above components, the principles of the embodiments of the present application are explained below.

[0062] It can be understood that, in the local oscillator optical path, a non-polarization-maintaining optical fiber can be used to couple the first local oscillator light into a single-mode coupler, and the single-mode coupler can transmit the first local oscillator light to the optical splitter. Further, the optical splitter can perform optical splitting processing on the first local oscillator light to obtain multiple second local oscillator lights, and the optical splitter can transmit each second local oscillator light to each polarization rotation beam splitter respectively. Further, inside the polarization rotation beam splitter, the second local oscillator light can first be divided into a third local oscillator light and a fourth local oscillator light, the third local oscillator light can be a TM0 mode optical signal, and the fourth local oscillator light can be a TE0 mode optical signal, and then the third local oscillator light can be converted into a TE0 mode optical signal to obtain a fifth local oscillator light, and then the fifth local oscillator light can be transmitted to an input port of mixer 1 in the echo optical path corresponding to the current polarization rotation beam splitter, and the fourth local oscillator light can be transmitted to an input port of 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 can be a local oscillator light of random polarization state. In the polarization rotation beam splitter, the local oscillator lights of different polarization states in the first local oscillator light can be split and processed, and then a TM0 mode optical signal and a TE0 mode optical signal can be obtained. Then, the TM0 mode optical signal can be converted into a TE0 mode optical signal and transmitted to the echo signal. In the echo optical path, the processing process of the first echo light, as well as the processing process of the fifth local oscillator light and the fourth local oscillator light can be specifically referred to. Figure 2 The processing process in will not be repeated here.

[0063] The embodiment of the present application is a light beam receiving device that can realize multiple channels to receive echo signals. The local oscillator light input in each echo optical path is input after a splitting process using a beam splitter and then beam splitting and mode conversion processing by a polarization rotation beam splitter. The implementation method of one single-mode coupler corresponding to one echo optical path is not adopted, but the number of single-mode couplers is reduced, and the beam splitter and polarization rotation beam splitter in the local oscillator optical path can be integrated on the chip. Therefore, in Figure 4On the basis of the illustrated embodiment, the coupling loss and chip area can also be reduced. That is to say, the present application can reduce the impact of the walk-off effect on the receiving system, improve the ranging capability of the receiving system, and at the same time increase the integration of the silicon-based optoelectronic integrated chip.

[0064] See also Figure 6 , is a schematic diagram of a light beam receiving device provided in an embodiment of the present application. The light beam receiving device includes a local oscillator light path and an echo light path, and the echo light path includes four mixers and four balanced detectors. The mode conversion device in the echo light path includes a few-mode coupler, a mode demultiplexer, and a mode converter for explanation below.

[0065] like Figure 6 As shown, the optical beam receiving device of the embodiment of the present application may include a single-mode coupler, a splitter, a few-mode coupler, a mode demultiplexer, a mode converter, mixer 1, mixer 2, mixer 3, mixer 4, balanced detector 1, balanced detector 2, balanced detector 3 and balanced detector 4.

[0066] exist Figure 6 In the embodiment, for the local oscillator 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 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; for the echo optical path, the few-mode coupler is connected to the input port of the mode demultiplexer, the output port of the mode demultiplexer is connected to the input port of the mode converter, the four output ports of the mode converter are respectively connected to another input port of mixer 1, another input port of mixer 2, another input port of mixer 3, and another input port of mixer 4, the output port of mixer 1 is connected to balanced detector 1, the output port of mixer 2 is connected to balanced detector 2, the output port of mixer 3 is connected to balanced detector 3, and the output port of mixer 4 is connected to balanced detector 4.

[0067] Based on the connection relationship between the above components, the principles of the embodiments of the present application are explained below.

[0068] It can be understood that, in the local oscillator optical path, a polarization-maintaining optical fiber can be used to couple the first local oscillator light to a single-mode coupler, and the single-mode coupler can transmit the first local oscillator light to an optical splitter. Further, the optical splitter can perform optical splitting processing on the first local oscillator light to obtain four second local oscillator lights, and the optical splitter can transmit the four second local oscillator lights 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 optical path. Since the polarization-maintaining optical fiber can only transmit polarized light of a certain polarization state, the first local oscillator light transmitted by the single-mode coupler can be a TE0 mode optical signal, and the four second local oscillator lights that come out of the optical splitter are still TE0 mode optical signals.

[0069] In the echo optical path, a few-mode optical fiber can be selected to couple the first echo light to the least-mode coupler. The few-mode optical fiber can be specifically a two-mode optical fiber, a three-mode optical fiber, a four-mode optical fiber, etc. At this time, the first echo light can contain optical signals of TE mode and TM mode, and the few-mode coupler can transmit the first echo light containing the above modes to the mode demultiplexer. Further, inside the mode demultiplexer, the optical signal containing TM mode and TE mode in the first echo light can be divided into four different optical paths for transmission, one optical path can transmit the optical signal of TE0 mode, one optical path can transmit the optical signal of TE1 mode, one optical path can transmit the optical signal of TM0 mode, and another optical path can transmit the optical signal of TM1 mode. For the convenience of description, the optical signal of TE0 mode can be called the second echo light, the optical signal of TE1 mode can be called the third echo light, the optical signal of TM0 mode can be called the fourth echo light, and the optical signal of TM1 mode can be called the fifth echo light. Then, the mode demultiplexer can 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 can convert the third echo light, that is, the optical signal of the TE1 mode, into the optical signal of the TE0 mode. For the convenience of description, the optical signal after the conversion of the third echo light can be called the sixth echo light; similarly, the mode converter can convert the fourth echo light, that is, the optical signal of the TM0 mode, into the optical signal of the TE0 mode to obtain the seventh echo light; similarly, the mode converter can also convert the fifth echo light, that is, the optical signal of the TM1 mode, into the optical signal of the TE0 mode to obtain the eighth echo light. Then, the mode converter can transmit the second echo light to another input port of mixer 1, can transmit the sixth echo light to another input port of mixer 2, can transmit the seventh echo light to another input port of mixer 3, and can transmit the eighth echo light to another input port of mixer 4. Further, mixer 1 can receive the second local oscillator light and the second echo light, both of which are TE0 mode light signals; similarly, mixer 2 can receive the third local oscillator light and the sixth echo light, both of which are TE0 mode light signals; similarly, mixer 3 can receive the fourth local oscillator light and the seventh echo light, both of which are TE0 mode light signals; similarly, mixer 4 can receive the fourth and fifth local oscillator lights and the eighth echo light, both of which are TE0 mode light signals. Further, after each mixer performs mixing processing on the TE0 mode local oscillator light and the echo light, the mixed light obtained by mixing is then transmitted to the balanced detector corresponding to each mixer, and the balanced detector converts the mixed light into an electrical signal. The detection information of the detected target can be obtained by correspondingly processing the electrical signal, and the detection information may include the values ​​of parameters such as distance, speed, azimuth, altitude, and attitude.Specifically, the detection information of the detection target can be obtained based on the electrical signal, mainly the distance and speed can be obtained based on the electrical signal. Further, by performing corresponding data processing on the speed and distance, the values ​​of parameters such as azimuth, altitude, and attitude can be obtained.

[0070] When the scheme of the embodiment of the present application is executed, a few-mode coupler is used to receive the echo signal. Since the mode field of the few-mode coupler is large, more echo signals can be received in the presence of the walk-off effect, that is, the reception 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, and can not only transmit the TE mode optical signal and the TM mode optical signal, but also convert the TM mode optical signal into the TE mode optical signal, and then transmit the TE mode optical signal to the mixer for beat frequency processing, and then transmit the optical signal obtained by the beat frequency processing to the balanced detector for subsequent signal processing, which can improve the utilization rate of the received echo signal. Therefore, the embodiment of the present application can realize the reception of echo signals of different polarization states, and then the transverse magnetic mode optical signal can be converted into the transverse electric mode optical signal, and the non-fundamental mode can also be converted into the fundamental mode, thereby improving the utilization rate of the received echo signal, reducing the influence of the walk-off effect on the receiving system, and improving the ranging capability of the receiving system. In addition, the embodiments of the present application also have high integration and design flexibility, which can improve the ranging capability of the receiving system while reducing the size and cost of the receiving system.

[0071] See also Figure 7 , is a schematic diagram of a light beam receiving device provided in an embodiment of the present application. The light beam receiving device includes one local oscillator light path and multiple echo light paths, and each echo light path includes four mixers and four balanced detectors, and the mode conversion device in the echo light path includes a few-mode coupler, a mode demultiplexer, and a mode converter for explanation below.

[0072] like Figure 7 As shown, the optical beam receiving device of 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, mixer 1, mixer 2, mixer 3, mixer 4, balanced detector 1, balanced detector 2, balanced detector 3 and balanced detector 4. Figure 7 In the embodiment, the number of the second optical splitters is equal to the number of the return optical paths. The embodiment of the present application shows two return optical paths and two second optical splitters for illustration.

[0073] exist Figure 7In the embodiment, for the local oscillator optical path, the input port of the first optical splitter is connected to the single-mode coupler, the output port of the first optical splitter is respectively connected to the input port of each second optical splitter, and the four output ports of each second optical splitter are respectively connected to one input port of mixer 1, one input port of mixer 2, one input port of mixer 3, and one input port of mixer 4 in the echo optical path, wherein the number of second optical splitters is equal to the number of echo optical paths. For each echo optical path, the few-mode coupler is connected to the input port of the mode demultiplexer, the output port of the mode demultiplexer is connected to the input port of the mode converter, the four output ports of the mode converter are respectively connected to another input port of mixer 1, another input port of mixer 2, another input port of mixer 3, and another input port of mixer 4, the output port of mixer 1 is connected to balanced detector 1, the output port of mixer 2 is connected to balanced detector 2, the output port of mixer 3 is connected to balanced detector 3, and the output port of mixer 4 is connected to balanced detector 4.

[0074] Based on the connection relationship between the above components, the principles of the embodiments of the present application are explained below.

[0075] It can be understood that, in the local oscillator optical path, a polarization-maintaining optical fiber can be used to couple the first local oscillator light to a single-mode coupler, and the single-mode coupler can transmit the first local oscillator light to the first optical splitter. Further, the first optical splitter can perform optical splitting processing on the first local oscillator light to obtain multiple second local oscillator lights, and the first optical splitter can transmit each second local oscillator light to each second optical splitter respectively. Further, the second optical splitter can perform optical splitting processing on the second local oscillator light to obtain the third local oscillator light, the fourth local oscillator light, the fifth local oscillator light and the sixth local oscillator light, and transmit the third local oscillator light to an input port of mixer 1 in each echo optical path, transmit the fourth local oscillator light to an input port of mixer 2 in each echo optical path, transmit the fifth local oscillator light to an input port of mixer 3 in each echo optical path, and transmit the sixth local oscillator light to an input port of mixer 4 in each echo optical path. In the echo light path, the processing of the first echo light, as well as the processing of the third local oscillation light, the fourth local oscillation light, the fifth local oscillation light, and the sixth local oscillation light can be found in detail. Figure 6 The processing process in will not be repeated here.

[0076] The embodiment of the present application is a light beam receiving device that can realize multiple channels to receive echo signals. The local oscillator light input in each echo optical path is obtained after two splitting processes using a first optical splitter and a second optical splitter. The implementation method of one echo optical path corresponding to one single-mode coupler is not adopted, but the number of single-mode couplers is reduced, and the single-mode coupler, the first optical splitter and the second optical splitter in the local oscillator optical path can be integrated on a chip. Therefore, in Figure 6 On the basis of the illustrated embodiment, the coupling loss and chip area can also be reduced. That is to say, the present application can reduce the impact of the walk-off effect on the receiving system, improve the ranging capability of the receiving system, and at the same time increase the integration of the silicon-based optoelectronic integrated chip.

[0077] It should be noted that, in the above embodiments, receiving local oscillator light of different polarization states and receiving echo light of different polarization states are respectively realized. In some embodiments, polarization diversity reception of local oscillator light and polarization diversity reception of echo light can be realized simultaneously. The present application does not impose any limitation on this. The specific implementation method can refer to the polarization diversity reception in the above description process.

[0078] Furthermore, the present application also provides a method for receiving a light beam, see Figure 8 , is a flow chart of a light beam receiving method according to an embodiment of the present application, wherein the light beam receiving method is applied to a light beam receiving device, wherein the light beam receiving device comprises a local oscillator optical path and at least one echo optical path, wherein each echo optical path comprises a mode conversion device, at least two mixers, and a balanced detector corresponding to each mixer; wherein the local oscillator optical path is respectively connected to the at least two mixers; wherein the mode conversion device is respectively connected to the at least two mixers; and wherein each mixer is connected to each balanced detector.

[0079] S801: The local oscillator optical path divides the first local oscillator light into at least two second local oscillator lights, and transmits each of the second local oscillator lights to each of the echo optical paths respectively.

[0080] In some embodiments, when the light beam receiving device includes a local oscillator optical path and an echo optical path, the local oscillator optical path may include a single-mode coupler and a 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 components can be seen in Figure 2 The schematic diagram shown will not be repeated here.

[0081] It can be understood that, in the local oscillator optical path, a polarization-maintaining optical fiber can be used to couple the first local oscillator light to a single-mode coupler, and the single-mode coupler can transmit the first local oscillator light to a splitter. Further, the splitter can split the first local oscillator light to obtain two second local oscillator lights, and the splitter can transmit the two second local oscillator lights to an input port of the first mixer (mixer 1) and an input port of the second mixer (mixer 2) of the echo optical path. The first local oscillator light transmitted by the single-mode coupler can be a TE0 mode optical signal, and the two second local oscillator lights that come out of the splitter are still TE0 mode optical signals.

[0082] In some embodiments, when the light beam receiving device includes one local oscillator optical path and multiple echo optical paths, each 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 local oscillator optical path may include 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. The connection relationship between the above components can be seen in Figure 3 The schematic diagram shown will not be repeated here.

[0083] It can be understood that, in the local oscillator optical path, a polarization-maintaining optical fiber can be used to couple the first local oscillator light into a single-mode coupler, and the single-mode coupler can transmit the first local oscillator light to the first optical splitter; further, the first optical splitter can perform optical splitting processing on the first local oscillator light to obtain multiple second local oscillator lights, and the first optical splitter can transmit each second local oscillator light to each second optical splitter respectively; further, each second optical splitter can split each second local oscillator light into a third local oscillator light and a fourth local oscillator light, and each second optical splitter can transmit the third local oscillator light to an input port of the first mixer (mixer 1) of each echo optical path, and can transmit the fourth local oscillator light to an input port of the second mixer (mixer 2) of each echo optical path. The first local oscillator light transmitted by the single-mode coupler can be a TE0 mode optical signal, and each second local oscillator light coming out after the first optical splitter is also a TE0 mode optical signal, and the third local oscillator light and the fourth local oscillator light coming out after each second optical splitter are still TE0 mode optical signals.

[0084] In some embodiments, when the light beam receiving device includes a local oscillator optical path and 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 mixer, and a second balanced detector corresponding to the second mixer; the local oscillator optical path includes a single-mode coupler and a polarization rotation beam splitter. The connection relationship between the above components can be seen in Figure 4 The schematic diagram shown will not be repeated here.

[0085] It can be understood that, in the local oscillator optical path, a non-polarization-maintaining optical fiber can be used to couple the first local oscillator light into a single-mode coupler, and the single-mode coupler can transmit the first local oscillator light to a polarization rotation beam splitter. Further, inside the polarization rotation beam splitter, first, the first local oscillator light can be divided into two local oscillator lights of orthogonal linear polarization states, that is, one can be a local oscillator light of the TE0 mode, which can be called the second local oscillator light for the convenience of description, and the other can be a local oscillator light of the TM0 mode, which can be called the third local oscillator light for the convenience of description; then, the local oscillator light of the TM0 mode can be converted into the local oscillator light of the TE0 mode, that is, the third local oscillator light can be converted into the local oscillator light of the fourth mode; then, the second local oscillator light can be transmitted to an input port of the first mixer (mixer 1) in the echo optical path, and the fourth local oscillator light can be transmitted to an input port of the second mixer (mixer 2) in the echo optical path. Therefore, non-polarization-maintaining fiber is used to couple the local oscillator light to the single-mode coupler, and then the single-mode coupler transmits the local oscillator light to the polarization rotation beam splitter. Since non-polarization-maintaining fiber can transmit randomly polarized light, unlike polarization-maintaining fiber which can only transmit polarized light in a certain direction, after the local oscillator light passes through the polarization rotation beam splitter, the local oscillator light of other polarization states (local oscillator light of TM0 mode) can be converted into local oscillator light of TE0 mode. Therefore, the use of non-polarization-maintaining fiber and the subsequent use of polarization rotation beam splitter can save fiber costs.

[0086] In some embodiments, when the light beam receiving device includes one local oscillator 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 mixer, and a second balanced detector corresponding to the second mixer; the local oscillator optical path includes a beam splitter and at least two polarization rotation beam splitters, and the number of the polarization rotation beam splitters is equal to the number of the echo optical paths. The connection relationship between the above components can be seen in Figure 5 The schematic diagram shown will not be repeated here.

[0087] It can be understood that, in the local oscillator optical path, a non-polarization-maintaining optical fiber can be used to couple the first local oscillator light into a single-mode coupler, and the single-mode coupler can transmit the first local oscillator light to the optical splitter. Further, the optical splitter can perform optical splitting processing on the first local oscillator light to obtain multiple second local oscillator lights, and the optical splitter can transmit each second local oscillator light to each polarization rotation beam splitter respectively. Further, inside the polarization rotation beam splitter, the second local oscillator light can first be divided into a third local oscillator light and a fourth local oscillator light, the third local oscillator light can be a TM0 mode optical signal, and the fourth local oscillator light can be a TE0 mode optical signal, and then the third local oscillator light can be converted into a TE0 mode optical signal to obtain a fifth local oscillator light, and then the fifth local oscillator light can 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 oscillator light can 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 can be a local oscillator light of a random polarization state. Inside the polarization rotation beam splitter, the local oscillator lights of different polarization states in the first local oscillator light can be split, and then a TM0 mode optical signal and a TE0 mode optical signal can be obtained. Then, the TM0 mode optical signal can be converted into a TE0 mode optical signal and transmitted to the echo signal. Therefore, the present application does not adopt the implementation method of one single-mode coupler corresponding to one echo optical path, but reduces the number of single-mode couplers, and can integrate the optical splitter and polarization rotation beam splitter in the local oscillator optical path on the chip, which can reduce coupling loss and chip area.

[0088] In some embodiments, when the light beam receiving device includes a local oscillator 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 mixer, a second balanced detector corresponding to the second mixer, a third 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 a splitter. The connection relationship between the above components can be seen in Figure 6 The schematic diagram shown will not be repeated here.

[0089] It can be understood that, in the local oscillator optical path, a polarization-maintaining optical fiber can be used to couple the first local oscillator light to a single-mode coupler, and the single-mode coupler can transmit the first local oscillator light to a splitter. Further, the splitter can split the first local oscillator light to obtain four second local oscillator lights, and the splitter can 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. Since the polarization-maintaining optical fiber can only transmit polarized light of a certain polarization state, the first local oscillator light transmitted by the single-mode coupler can be a TE0 mode optical signal, and the four second local oscillator lights that come out of the splitter are still TE0 mode optical signals.

[0090] In some embodiments, when the light beam receiving device includes one local oscillator 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 mixer, a second balanced detector corresponding to the second mixer, a third 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 includes 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. For the connection relationship between the above components, see Figure 7 The schematic diagram shown will not be repeated here.

[0091] It can be understood that, in the local oscillator optical path, a polarization-maintaining optical fiber can be used to couple the first local oscillator light to a single-mode coupler, and the single-mode coupler can transmit the first local oscillator light to the first optical splitter. Further, the first optical splitter can perform optical splitting processing on the first local oscillator light to obtain multiple second local oscillator lights, and the first optical splitter can transmit each second local oscillator light to each second optical splitter. Further, the second optical splitter can perform optical splitting processing on the second local oscillator light to obtain the third local oscillator light, the fourth local oscillator light, the fifth local oscillator light and the sixth local oscillator light, and 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 present application does not adopt the implementation method of one single-mode coupler corresponding to one echo optical path, but reduces the number of single-mode couplers, and can integrate the single-mode coupler, the first splitter and the second splitter in the local oscillator optical path on the chip, which can reduce coupling loss and chip area.

[0092] S802, each echo light path converts each first echo light into at least two second echo lights of a preset pattern, and determines at least two detection information of the detection target based on each second echo light and each second local oscillation light.

[0093] In some embodiments, for Figure 2In the light beam receiving device shown, in the echo optical path, a few-mode optical fiber can be selected to couple the first echo light to the at least-mode coupler. The few-mode optical fiber can specifically be a two-mode optical fiber, a three-mode optical fiber, a four-mode optical fiber, etc. At this time, the first echo light can contain optical signals of TE0 mode and TE1 mode, and the few-mode coupler can transmit the first echo light containing the two modes to the mode demultiplexer; inside the mode demultiplexer, the optical signals of the two modes contained in the first echo light can be divided into optical signals transmitted by two different optical paths, one optical path can transmit the optical signal of TE0 mode, and the other optical path can transmit the optical signal of TE1 mode. For the convenience of description, the optical signal of TE0 mode can be called the second echo light, and the optical signal of TE1 mode can be called the third echo light. Then, the mode demultiplexer can transmit the second echo light and the third echo light to two different input ports of the mode converter respectively; further, the mode converter can convert the third echo light, that is, the optical signal of TE1 mode, into TE 0 mode optical signal, for the convenience of description, the optical signal after the conversion of the third echo light can be called the fourth echo light, at this time, the fourth echo light and the second echo light are both TE0 mode optical signals; further, the mode converter can transmit the second echo light and the fourth echo light to another input port of mixer 1 and another input port of mixer 2 respectively; further, mixer 1 can receive the second echo light and the second local oscillation light, the second echo light and the second local oscillation light are both TE0 mode optical signals, at the same time, mixer 2 can also receive the fourth echo light and the second local oscillation light, the fourth echo light and the second local oscillation light are also TE0 mode optical signals, the two mixers can mix the fundamental mode, and then transmit the mixed optical signal to the balanced detector; further, the balanced detector can convert the mixed light into an electrical signal, and the detection information of the detected target can be obtained by correspondingly processing the electrical signal, and the detection information can include the 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, and mainly the distance and speed can be obtained according to the electrical signal. Further, the speed and distance are processed accordingly to obtain the values ​​of parameters such as azimuth, altitude, and attitude. The embodiment of the present application adopts a few-mode coupler to receive the echo signal. Since the mode field of the few-mode coupler is large, more echo signals can be received in the presence of the walk-off effect. Then, a mode converter is used to convert the TE1 mode optical signal in the echo signal into a TE0 mode optical signal. Although there is conversion loss, the loss is small. When the mixer is subsequently beat, since the local oscillator light and the echo light are both optical signals of the same mode, a better beat effect can be achieved. That is to say, the present application can receive more echo signals, and most of the energy in the echo signal can be received. Then, subsequent signal processing can be performed, thereby reducing the impact of the walk-off effect on the receiving system and improving the ranging capability of the receiving system.

[0094] In some embodiments, for Figure 3 , 4 , 5. The light beam receiving device shown in FIG. 5, in the return light path, the light signal processing process can be specifically referred to in Figure 2 The processing process in will not be repeated here.

[0095] In some embodiments, for Figure 6In the light beam receiving device shown, in the echo light path, a few-mode optical fiber can be selected to couple the first echo light into a least-mode coupler. The few-mode optical fiber can specifically be a two-mode optical fiber, a three-mode optical fiber, a four-mode optical fiber, etc. At this time, the first echo light can contain TE mode and TM mode optical signals, and the few-mode coupler can transmit the first echo light containing the above modes to the mode demultiplexer. Furthermore, inside the mode demultiplexer, the optical signal containing the TM mode and the TE mode in the first echo light can be divided into four different optical paths for transmission. One optical path can transmit the optical signal of the TE0 mode, one optical path can transmit the optical signal of the TE1 mode, one optical path can transmit the optical signal of the TM0 mode, and another optical path can transmit the optical signal of the TM1 mode. For the convenience of description, the optical signal of the TE0 mode can be called the second echo light, the optical signal of the TE1 mode can be called the third echo light, the optical signal of the TM0 mode can be called the fourth echo light, and the optical signal of the TM1 mode can be called the fifth echo light. Then, the mode demultiplexer can 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 can convert the third echo light, that is, the optical signal of the TE1 mode, into the optical signal of the TE0 mode. For the convenience of description, the optical signal after the conversion of the third echo light can be called the sixth echo light; similarly, the mode converter can convert the fourth echo light, that is, the optical signal of the TM0 mode, into the optical signal of the TE0 mode to obtain the seventh echo light; similarly, the mode converter can also convert the fifth echo light, that is, the optical signal of the TM1 mode, into the optical signal of the TE0 mode to obtain the eighth echo light. Then, the mode converter can transmit the second echo light to another input port of mixer 1, can transmit the sixth echo light to another input port of mixer 2, can transmit the seventh echo light to another input port of mixer 3, and can transmit the eighth echo light to another input port of mixer 4. Further, mixer 1 can receive the second local oscillator light and the second echo light, both of which are TE0 mode light signals; similarly, mixer 2 can receive the third local oscillator light and the sixth echo light, both of which are TE0 mode light signals; similarly, mixer 3 can receive the fourth local oscillator light and the seventh echo light, both of which are TE0 mode light signals; similarly, mixer 4 can receive the fourth and fifth local oscillator lights and the eighth echo light, both of which are TE0 mode light signals. Further, after each mixer performs mixing processing on the TE0 mode local oscillator light and the echo light, the mixed light obtained by mixing is then transmitted to the balanced detector corresponding to each mixer, and the balanced detector converts the mixed light into an electrical signal. The detection information of the detected target can be obtained by correspondingly processing the electrical signal, and the detection information may include the 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 speed can be obtained according to the electrical signal, and further, the speed and distance are processed accordingly to obtain the values ​​of parameters such as azimuth, altitude, and attitude. The mode demultiplexer and mode converter used in the embodiment of the present application can collect all the energy of the optical signal coupled into the few-mode coupler, and can not only transmit the TE mode optical signal and the TM mode optical signal, but also convert the TM mode optical signal into the TE mode optical signal, and then transmit the TE mode optical signal to the mixer for beat frequency processing.

[0096] In some embodiments, for Figure 7 The light beam receiving device shown in the figure, in the return light path, the processing process of the light signal can be specifically referred to Figure 6 The processing process in will not be repeated here.

[0097] The embodiment of the present application is not only applicable to a beam receiving device for receiving echo signals through a single channel, but also to a beam receiving device for receiving echo signals through multiple channels. Whether it is a single channel or multiple channels, polarization diversity reception of echo signals can be realized. In addition, the present application can convert the non-fundamental mode signal in the received echo signal into a fundamental mode signal with a very small mode conversion loss, and can perform beat frequency processing on the local oscillator light and the echo light in the fundamental mode form in the mixer, so as to achieve a good beat frequency effect. Therefore, the embodiment of the present application not only realizes the polarization diversity reception of the echo signal, but also utilizes the characteristics of the large receiving end face of the few-mode coupler to improve the reception efficiency of the echo signal, and can also improve the utilization rate of the received echo signal on the chip, thereby reducing the influence of the walk-off effect on the receiving system, and improving the ranging capability of the receiving system. In addition, when realizing multi-channel reception of echo signals, the present application can reduce the number of single-mode couplers used, thereby reducing coupling loss and chip area, and on the basis of improving ranging capability, can also increase the integration of silicon-based optoelectronic integrated chips, so that the receiving system has better design flexibility, and can reduce the volume and cost of the receiving system.

[0098] It should be noted that, in the above method embodiment, polarization diversity reception of local oscillator light is described in S801, and polarization diversity reception of echo light is described in S802. In some embodiments, polarization diversity reception of local oscillator light and polarization diversity reception of echo light can be implemented simultaneously. The present application does not impose any restrictions on this. The specific implementation method can refer to the polarization diversity reception in the above description process.

[0099] The above description is only an optional embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A light beam receiving device, characterized in that: It comprises a local oscillator optical path and at least one echo optical path, each echo optical path comprises a mode conversion device, at least two mixers and a balanced detector corresponding to each mixer, the mode conversion device comprises a few-mode coupler, a mode demultiplexer and a mode converter, the local oscillator optical path is connected to each mixer, the output port of the few-mode coupler is connected to the input port of the mode demultiplexer, the output port of the mode demultiplexer is connected to the input port of the mode converter, the output port of the mode converter is connected to the mixer, and each mixer is respectively connected to the balanced detector corresponding to each mixer; wherein: The local oscillator optical path is used to transmit a first local oscillator light, and to divide the first local oscillator light into at least two second local oscillator lights, and to transmit each of the second local oscillator lights to each of the echo optical paths; wherein, When the light beam receiving device includes one echo optical path, the local oscillator optical path includes a single-mode coupler and a beam splitter, and the input port of the beam splitter is connected to the single-mode coupler, or the local oscillator optical path includes the single-mode coupler and a polarization rotation beam splitter, and the input port of the polarization rotation beam splitter is connected to the single-mode coupler; When the light beam receiving device includes multiple echo optical paths, the local oscillator optical path includes the single-mode coupler, the first optical splitter and at least two second optical splitters, the number of the second optical splitters is equal to the number of the echo optical paths, the first optical splitter includes an input port and at least two output ports, the single-mode coupler is connected to the input port of the first optical splitter, each output port of the first optical splitter is respectively connected to the input port of each second optical splitter, and the number of the output ports of the first optical splitter is equal to the number of the second optical splitter; or, the local oscillator optical path includes the single-mode coupler, the optical splitter and at least two polarization rotation beam splitters, the number of the polarization rotation beam splitters is equal to the number of the echo optical paths, the optical splitter includes an input port and at least two output ports, the single-mode coupler is connected to the input port of the optical splitter, each output port of the optical splitter is respectively connected to the input port of each polarization rotation beam splitter, and the number of the output ports of the optical splitter is equal to the number of the polarization rotation beam splitters; In each of the echo optical paths, each few-mode coupler is used to transmit each first echo light to each mode demultiplexer; In each of the echo light paths, each mode demultiplexer is used to convert each of the first echo lights into at least two echo lights of different modes; In each echo light path, each mode converter is used to convert the at least two echo lights of different modes into at least two second echo lights of preset modes; Each echo light path is used to determine at least two detection information of a detection target based on each second echo light and each second local oscillation light; The at least two different modes include a fundamental mode of a transverse electric mode, a non-fundamental transverse electric mode, a fundamental mode of a transverse magnetic mode, and a non-fundamental transverse magnetic mode, and the preset mode is a fundamental mode.

2. The light beam receiving device according to claim 1, characterized in that: When the light beam receiving device includes an echo optical path, the 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 includes a single-mode coupler and a splitter; wherein: The first input port of the first mixer is connected to the first output port of the mode converter, the second input port of the first mixer is connected to the first output port of the optical splitter, and the output port of the first mixer is connected to the first balanced detector; The first input port of the second mixer is connected to the second output port of the mode converter, the second input port of the second mixer is connected to the second output port of the optical splitter, and the output port of the second mixer is connected to the second balanced detector; The first input port of the mode converter is connected to the first output port of the mode demultiplexer, and the second input port of the mode converter is connected to the second output port of the mode demultiplexer; The single-mode coupler is connected to the input port of the optical splitter.

3. The light beam receiving device according to claim 2, characterized in that: The single-mode coupler is used to transmit the first local oscillation light to the optical splitter; The optical splitter is used to split the first local oscillation light into a second local oscillation light and a third local oscillation light, and transmit the second local oscillation light to the first mixer, and transmit the third local oscillation light to the second mixer; the second local oscillation light and the third local oscillation light are optical signals of the same mode; The mode demultiplexer is used to convert the 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 the mode converter, wherein the second echo light and the third echo light are optical signals of different modes; The mode converter is used to convert the third echo light into a fourth echo light, and transmit the second echo light to the first mixer, and transmit the fourth echo light to the second mixer, wherein the fourth echo light and the second echo light are optical signals of the same mode; The first mixer is used to perform 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 mixer is used to perform 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 balanced detector obtains first detection information based on the first mixed frequency light; The second balanced detector obtains second detection information based on the second mixed frequency light.

4. The light beam receiving device according to claim 1, characterized in that: When the light beam receiving device 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 includes 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 of the echo optical paths, the first input port of the first mixer is connected to the first output port of the mode converter, the second input port of the first mixer is connected to the first output port of the second optical splitter, and the output port of the first mixer is connected to the first balanced detector; In each of the echo optical paths, the first input port of the second mixer is connected to the second output port of the mode converter, the second input port of the second mixer is connected to the second output port of the second optical splitter, and the output port of the second mixer is connected to the second balanced detector; In each of the echo optical paths, the first input port of the mode converter is connected to the first output port of the mode demultiplexer, and the second input port of the mode converter is connected to the second output port of the mode demultiplexer; The first optical splitter includes an input port and at least two output ports, the input port of the first optical splitter is connected to the single-mode coupler, each output port of the first optical splitter is respectively connected to the input port of each second optical splitter, and the number of the output ports of the first optical splitter is equal to the number of the second optical splitter.

5. The light beam receiving device according to claim 4, characterized in that: The single-mode coupler is used to transmit the first local oscillation light to the first optical splitter; The first beam splitter is used to split the first local oscillation light into at least two second local oscillation lights, and transmit each second local oscillation light to each second beam splitter respectively, and the number of the second beam splitters is equal to the number of the second local oscillation lights; Each of the second optical splitters is used to split each second local oscillation light into a third local oscillation light and a fourth local oscillation light, and transmit the third local oscillation light to the first mixer in each echo optical path, and transmit the fourth local oscillation light to the second mixer in each echo optical path; the third local oscillation light and the fourth local oscillation light are optical signals of the same mode; In each of the echo optical paths, the few-mode coupler is used to transmit each first echo light to each mode demultiplexer; Each of the mode demultiplexers is used to convert each of the first echo lights 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, wherein the second echo light and the third echo light are optical signals of different modes; Each of the mode converters is used to convert the third echo light into a fourth echo light, and transmit the second echo light to each first mixer, and transmit the fourth echo light to each second mixer, wherein the fourth echo light and the second echo light are optical signals of the same mode; Each of the first frequency mixers is used to perform frequency mixing processing on the third local oscillation light and the second echo light to obtain each first frequency mixed light, and transmit each first frequency mixed light to each first balanced detector; Each of the second frequency mixers is used to perform frequency mixing processing on the fourth local oscillation light and the fourth echo light to obtain each second frequency mixed light, and transmit each second frequency mixed light to each second balanced detector; Each of the first balanced detectors obtains each first detection information based on each of the first mixed-frequency lights; Each of the second balanced detectors obtains each second detection information based on each of the second mixed-frequency lights.

6. The light beam receiving device according to claim 1, characterized in that: When the light beam receiving device includes an echo optical path, the 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 includes a single-mode coupler and a polarization rotation beam splitter; wherein: The first input port of the first mixer is connected to the first output port of the mode converter, the second input port of the first mixer is connected to the first output port of the polarization rotating beam splitter, and the output port of the first mixer is connected to the first balanced detector; The first input port of the second mixer is connected to the second output port of the mode converter, the second input port of the second mixer is connected to the second output port of the polarization rotating beam splitter, and the output port of the second mixer is connected to the second balanced detector; The first input port of the mode converter is connected to the first output port of the mode demultiplexer, and the second input port of the mode converter is connected to the second output port of the mode demultiplexer; The single-mode coupler is connected to the input port of the polarization rotating beam splitter.

7. The light beam receiving device according to claim 6, characterized in that: The single-mode coupler is used to transmit the first local oscillation light to the polarization rotation beam splitter; The polarization rotation beam splitter is used to split the first local oscillation light into a second local oscillation light and a third local oscillation light, and convert the third local oscillation light into a fourth local oscillation light, and transmit the second local oscillation light to the first mixer, and transmit the fourth local oscillation light to the second mixer; the second local oscillation light and the third local oscillation light are optical signals of different modes, and the second local oscillation light and the fourth local oscillation light are optical signals of the same mode; The mode demultiplexer is used to convert the 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 the mode converter, wherein the second echo light and the third echo light are optical signals of different modes; The mode converter is used to convert the third echo light into a fourth echo light, and transmit the second echo light to the first mixer, and transmit the fourth echo light to the second mixer, wherein the fourth echo light and the second echo light are optical signals of the same mode; The first mixer is used to perform 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 mixer is used to perform 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; The first balanced detector obtains first detection information based on the first mixed frequency light; The second balanced detector obtains second detection information based on the second mixed frequency light.

8. The light beam receiving device according to claim 1, characterized in that: When the light beam receiving device 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 includes a single-mode coupler, a beam splitter, and at least two polarization rotation beam splitters, and the number of the polarization rotation beam splitters is equal to the number of the echo optical paths; wherein: In each of the return optical paths, the first input port of the first mixer is connected to the first output port of the mode converter, the second input port of the first mixer is connected to the first output port of each polarization rotation beam splitter, and the output port of the first mixer is connected to the first balanced detector; In each of the echo optical paths, the first input port of the second mixer is connected to the second output port of the mode converter, the second input port of the second mixer is connected to the second output port of each polarization rotation beam splitter, and the output port of the second mixer is connected to the second balanced detector; In each echo signal, the first input port of the mode converter is connected to the first output port of the mode demultiplexer, and the second input port of the mode converter is connected to the second output port of the mode demultiplexer; The optical splitter comprises an input port and at least two output ports, the input port of the optical splitter is connected to the single-mode coupler, each output port of the optical splitter is respectively connected to the input port of each polarization rotation beam splitter, and the number of the output ports of the optical splitter is equal to the number of the polarization rotation beam splitters.

9. The light beam receiving device according to claim 8, characterized in that: The single-mode coupler is used to transmit the first local oscillation light to the optical splitter; The beam splitter is used 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 respectively, and 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 used to split the second local oscillation light into a third local oscillation light and a fourth local oscillation light, convert the third local oscillation light into a fifth local oscillation light, and transmit the fifth local oscillation light to the first mixer in each echo optical path, and transmit the fourth local oscillation light to the second mixer in each echo optical path; the third local oscillation light and the fourth local oscillation light are optical signals of different modes; the fifth local oscillation light and the fourth local oscillation light are optical signals of the same mode; In each of the echo optical paths, the few-mode coupler is used to transmit each first echo light to each mode demultiplexer; Each of the mode demultiplexers is used to convert each of the first echo lights 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, wherein the second echo light and the third echo light are optical signals of different modes; Each of the mode converters is used to convert the third echo light into a fourth echo light, and transmit the second echo light to each first mixer, and transmit the fourth echo light to each second mixer, wherein the fourth echo light and the second echo light are optical signals of the same mode; Each of the first frequency mixers is used to perform frequency mixing processing on the fifth local oscillation light and the second echo light to obtain each first frequency mixed light, and transmit each first frequency mixed light to each first balanced detector; Each of the second frequency mixers is used to perform frequency mixing processing on the fourth local oscillation light and the fourth echo light to obtain each second frequency mixed light, and transmit each second frequency mixed light to each second balanced detector; Each of the first balanced detectors obtains each first detection information based on each of the first mixed-frequency lights; Each of the second balanced detectors obtains each second detection information based on each of the second mixed-frequency lights.

10. The light beam receiving device according to claim 1, characterized in that: When the light beam receiving device includes an echo optical path, the 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, a second balanced detector corresponding to the second mixer, a third 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 includes a single-mode coupler and a splitter; wherein: The first input port of the first mixer is connected to the first output port of the mode converter, the second input port of the first mixer is connected to the first output port of the optical splitter, and the output port of the first mixer is connected to the first balanced detector; The first input port of the second mixer is connected to the second output port of the mode converter, the second input port of the second mixer is connected to the second output port of the optical splitter, and the output port of the second mixer is connected to the second balanced detector; The first input port of the third mixer is connected to the third output port of the mode converter, the second input port of the third mixer is connected to the third output port of the optical splitter, and the output port of the third mixer is connected to the third balanced detector; The first input port of the fourth mixer is connected to the fourth output port of the mode converter, the second input port of the fourth mixer is connected to the fourth output port of the optical splitter, and the output port of the fourth mixer is connected to the fourth balanced detector; The first input port of the mode converter is connected to the first output port of the mode demultiplexer, the second input port of the mode converter is connected to the second output port of the mode demultiplexer, the third input port of the mode converter is connected to the third output port of the mode demultiplexer, and the fourth input port of the mode converter is connected to the fourth output port of the mode demultiplexer; The single-mode coupler is connected to the input port of the optical splitter.

11. The light beam receiving device according to claim 10, characterized in that: The single-mode coupler is used to transmit the first local oscillation light to the optical splitter; The optical splitter is used to split the first local oscillation light into a second local oscillation light, a third local oscillation light, a fourth local oscillation light and a fifth local oscillation light, and transmit the second local oscillation light to the first mixer, transmit the third local oscillation light to the second mixer, transmit the fourth local oscillation light to the third mixer, and transmit the fifth local oscillation light to the fourth mixer; the second local oscillation light, the third local oscillation light, the fourth local oscillation light and the fifth local oscillation light are optical signals of the same mode; The mode demultiplexer is used to convert the first echo light into the second echo light, the third echo light, the fourth echo light, and the fifth echo light, and transmit 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 of different modes respectively; The mode converter is used to convert the third echo light into a sixth echo light, convert the fourth echo light into a seventh echo light, convert the fifth echo light into an eighth echo light, and transmit the second echo light to the first mixer, the sixth echo light to the second mixer, the seventh echo light to the third mixer, and the eighth echo light to the fourth mixer, wherein 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 first mixer is used to perform 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 mixer is used to perform 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 used to perform 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 mixer is used to perform 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 first balanced detector obtains first detection information based on the first mixed frequency light; The second balanced detector obtains second detection information based on the second mixed frequency light; The third balanced detector obtains third detection information based on the third mixed frequency light; The fourth balanced detector obtains fourth detection information based on the fourth mixed-frequency light.

12. The light beam receiving device according to claim 1, characterized in that: When the light beam receiving device 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, a second balanced detector corresponding to the second mixer, a third 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 includes 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 of the echo optical paths, the first input port of the first mixer is connected to the first output port of the mode converter, the second input port of the first mixer is connected to the first output port of each second optical splitter, and the output port of the first mixer is connected to the first balanced detector; In each of the echo optical paths, the first input port of the second mixer is connected to the second output port of the mode converter, the second input port of the second mixer is connected to the second output port of each second optical splitter, and the output port of the second mixer is connected to the second balanced detector; In each of the echo optical paths, the first input port of the third mixer is connected to the third output port of the mode converter, the second input port of the third mixer is connected to the third output port of each second optical splitter, and the output port of the third mixer is connected to the third balanced detector; In each of the echo optical paths, the first input port of the fourth mixer is connected to the fourth output port of the mode converter, the second input port of the fourth mixer is connected to the fourth output port of each second optical splitter, and the output port of the fourth mixer is connected to the fourth balanced detector; In each echo signal, the first input port of the mode converter is connected to the first output port of the mode demultiplexer, the second input port of the mode converter is connected to the second output port of the mode demultiplexer, the third input port of the mode converter is connected to the third output port of the mode demultiplexer, and the fourth input port of the mode converter is connected to the fourth output port of the mode demultiplexer; The first optical splitter includes an input port and at least two output ports, the input port of the first optical splitter is connected to the single-mode coupler, each output port of the first optical splitter is respectively connected to the input port of each second optical splitter, and the number of the output ports of the first optical splitter is equal to the number of the second optical splitter.

13. The light beam receiving device according to claim 12, characterized in that: The single-mode coupler is used to transmit the first local oscillation light to the first optical splitter; The first beam splitter is used to split the first local oscillation light into at least two second local oscillation lights, and transmit each second local oscillation light to each second beam splitter respectively, and the number of the second beam splitters is equal to the number of the second local oscillation lights; Each of the second optical splitters is used to split the second local oscillation light into a third local oscillation light, a fourth local oscillation light, a fifth local oscillation light and a sixth local oscillation light, and transmit the third local oscillation light to the first mixer in each echo optical path, transmit the fourth local oscillation light to the second mixer in each echo optical path, transmit the fifth local oscillation light to the third mixer in each echo optical path, and transmit the sixth local oscillation light to the fourth mixer in each echo optical path; the third local oscillation light, the fourth local oscillation light, the fifth local oscillation light and the sixth local oscillation light are optical signals of the same mode; In each of the echo optical paths, the few-mode coupler is used to transmit each first echo light to each mode demultiplexer; Each mode demultiplexer is used to convert each of the first echo lights into second echo lights, third echo lights, fourth echo lights and fifth echo lights, and transmit the second echo lights, the third echo lights, the fourth echo lights and the fifth echo lights to each mode converter, wherein the second echo lights, the third echo lights, the fourth echo lights and the fifth echo lights are optical signals of different modes respectively; Each of the mode converters is used to convert the third echo light into a sixth echo light, convert the fourth echo light into a seventh echo light, convert the fifth echo light into an eighth echo light, and transmit the second echo light to each first mixer, transmit the 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, wherein the second echo light, the sixth echo light, the seventh echo light, and the eighth echo light are optical signals of the same mode; Each of the first frequency mixers is used to perform frequency mixing processing on the third local oscillation light and the second echo light to obtain each first frequency mixed light, and transmit each first frequency mixed light to each first balanced detector; Each of the second frequency mixers is used to perform frequency mixing processing on the fourth local oscillation light and the sixth echo light to obtain each second frequency mixed light, and transmit each second frequency mixed light to each second balanced detector; Each of the third frequency mixers is used to perform frequency mixing processing on the fifth local oscillation light and the seventh echo light to obtain each third frequency mixed light, and transmit each third frequency mixed light to each third balanced detector; Each of the fourth frequency mixers is used to perform frequency mixing processing on the sixth local oscillation light and the eighth echo light to obtain each fourth frequency mixed light, and transmit each fourth frequency mixed light to each fourth balanced detector; Each of the first balanced detectors obtains each first detection information based on each of the first mixed-frequency lights; Each second balanced detector obtains each second detection information based on each second mixed frequency light; Each of the third balanced detectors obtains each of the third detection information based on each of the third mixed-frequency lights; Each of the fourth balanced detectors obtains each fourth detection information based on each of the fourth mixed-frequency lights.

14. A light beam receiving method, applied to a light beam receiving device, the light beam receiving device comprising a local oscillator optical path and at least one echo optical path, each echo optical path comprising a mode conversion device, at least two mixers and a balanced detector corresponding to each mixer, the mode conversion device comprising a few-mode coupler, a mode demultiplexer and a mode converter; The local oscillator optical path is connected to the at least two mixers respectively; the output port of the few-mode coupler is connected to the input port of the mode demultiplexer, the output port of the mode demultiplexer is connected to the input port of the mode converter, and the output port of the mode converter is connected to the mixer; Each mixer is connected to each balanced detector, characterized in that the method comprises: The local oscillator optical path divides the first local oscillator light into at least two second local oscillator lights, and transmits each of the second local oscillator lights to each of the echo optical paths respectively; wherein, When the light beam receiving device includes one echo optical path, the local oscillator optical path includes a single-mode coupler and a beam splitter, and the input port of the beam splitter is connected to the single-mode coupler, or the local oscillator optical path includes the single-mode coupler and a polarization rotation beam splitter, and the input port of the polarization rotation beam splitter is connected to the single-mode coupler; When the light beam receiving device includes multiple echo optical paths, the local oscillator optical path includes the single-mode coupler, the first optical splitter and at least two second optical splitters, the number of the second optical splitters is equal to the number of the echo optical paths, the first optical splitter includes an input port and at least two output ports, the single-mode coupler is connected to the input port of the first optical splitter, each output port of the first optical splitter is respectively connected to the input port of each second optical splitter, and the number of the output ports of the first optical splitter is equal to the number of the second optical splitter; or, the local oscillator optical path includes the single-mode coupler, the optical splitter and at least two polarization rotation beam splitters, the number of the polarization rotation beam splitters is equal to the number of the echo optical paths, the optical splitter includes an input port and at least two output ports, the single-mode coupler is connected to the input port of the optical splitter, each output port of the optical splitter is respectively connected to the input port of each polarization rotation beam splitter, and the number of the output ports of the optical splitter is equal to the number of the polarization rotation beam splitters; In each of the echo light paths, 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 of different modes, and the mode converter converts the at least two echo lights of different modes into at least two second echo lights of preset modes; Each echo optical path determines at least two detection information of the detection target based on each second echo light and each second local oscillation light; The at least two different modes include a fundamental transverse electric mode, a non-fundamental transverse electric mode, a fundamental transverse magnetic mode and a non-fundamental transverse magnetic mode, and the preset mode is a fundamental mode.

15. The method according to claim 14, characterized in that 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 optical path includes a single-mode coupler and a splitter, the local oscillator optical path splits the first local oscillator light into at least two second local oscillator lights, and transmits each of the second local oscillator lights to each of the echo optical paths, including: The single-mode coupler transmits the first local oscillation light to the optical splitter; The optical splitter splits the first local oscillation light into a second local oscillation light and a third local oscillation light, and transmits the second local oscillation light to the first mixer, and transmits the third local oscillation light to the second mixer; the second local oscillation light and the third local oscillation light are optical signals of the same mode; When N is an integer greater than 1, the local oscillator optical path includes a single-mode coupler, a first optical splitter, and N second optical splitters, the local oscillator optical path splits the first local oscillator light into at least two second local oscillator lights, and transmits each of the second local oscillator lights to each of the echo optical paths, including: The single-mode coupler transmits the first local oscillation light to the first optical splitter; The first optical splitter splits the first local oscillation light into N fourth local oscillation lights, and transmits each fourth local oscillation light to each second optical splitter; Each of the second optical splitters splits each of the fourth local oscillation lights into a second local oscillation light and a third local oscillation light, and transmits the second local oscillation light to the first mixer, and transmits the third local oscillation light to the second mixer; the second local oscillation light and the third local oscillation light are optical signals of the same mode; Each echo light path is used to transmit each first echo light, and is used to convert each first echo light into at least two second echo lights of a preset mode, and to determine at least two detection information of a detection target based on each second echo light and each second local oscillation light, including: In each echo light path, the few-mode coupler transmits the first echo light to the mode demultiplexer; The mode demultiplexer converts the first echo light into a second echo light and a third echo light, and transmits the second echo light and the third echo light to the mode converter, wherein the second echo light and the third echo light are optical signals of different modes; The mode converter is used to convert the third echo light into a fourth echo light, and transmit the second echo light to the first mixer, and transmit the fourth echo light to the second mixer, wherein the fourth echo light and the second echo light are optical signals of the same mode; The first mixer is used to perform 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 mixer is used to perform 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 balanced detector obtains first detection information based on the first mixed frequency light; The second balanced detector obtains second detection information based on the second mixed frequency light.

16. The method according to claim 14, characterized in that 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 optical path includes a single-mode coupler and a polarization rotation beam splitter, the local oscillator optical path splits the first local oscillator light into at least two second local oscillator lights, and transmits each of the second local oscillator lights to each of the echo optical paths, including: The single-mode coupler transmits the first local oscillator light to the polarization rotation beam splitter; The polarization rotation beam splitter splits the first local oscillation light into a second local oscillation light and a third local oscillation light, converts the third local oscillation light into a fourth local oscillation light, transmits the second local oscillation light to the first mixer, and transmits the fourth local oscillation light to the second mixer; the second local oscillation light and the third local oscillation light are optical signals of different modes, and the second local oscillation light and the fourth local oscillation light are optical signals of the same mode; When N is an integer greater than 1, the local oscillator optical path includes a single-mode coupler, a beam splitter, and N polarization rotation beam splitters, the local oscillator optical path splits a first local oscillator light into at least two second local oscillator lights, and transmits each of the second local oscillator lights to each of the echo optical paths, including: The single-mode coupler transmits the first local oscillation light to the optical splitter; The beam splitter splits 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 splits each fifth local oscillation light into a second local oscillation light and a third local oscillation light, converts the third local oscillation light into a fourth local oscillation light, transmits the second local oscillation light to the first mixer, and transmits the fourth local oscillation light to the second mixer; the second local oscillation light and the third local oscillation light are optical signals of different modes, and the second local oscillation light and the fourth local oscillation light are optical signals of the same mode; Each echo light path is used to transmit each first echo light, and is used to convert each first echo light into at least two second echo lights of a preset mode, and to determine at least two detection information of a detection target based on each second echo light and each second local oscillation light, including: In each echo light path, the few-mode coupler transmits the first echo light to the mode demultiplexer; The mode demultiplexer converts the first echo light into a second echo light and a third echo light, and transmits the second echo light and the third echo light to the mode converter, wherein the second echo light and the third echo light are optical signals of different modes; The mode converter converts the third echo light into a 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 of the same mode; The first mixer performs mixing processing on the second local oscillator light and the second echo light to obtain first mixed light, and transmits the first mixed light to the first balanced detector; The second mixer performs 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; The first balanced detector obtains first detection information based on the first mixed frequency light; The second balanced detector obtains second detection information based on the second mixed frequency light.

17. The method according to claim 14, characterized in that 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, a second balanced detector corresponding to the second mixer, a third 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 optical path includes a single-mode coupler and a splitter, the local oscillator optical path splits the first local oscillator light into at least two second local oscillator lights, and transmits each of the second local oscillator lights to each of the echo optical paths, including: The single-mode coupler transmits the first local oscillation light to the optical splitter; The optical splitter splits the first local oscillation light into a second local oscillation light, a third local oscillation light, a fourth local oscillation light and a fifth local oscillation light, and transmits the second local oscillation light to the first mixer, transmits the third local oscillation light to the second mixer, transmits the fourth local oscillation light to the third mixer, and transmits the fifth local oscillation light to the fourth mixer; the second local oscillation light, the third local oscillation light, the fourth local oscillation light and the fifth local oscillation light are optical signals of the same mode; When N is an integer greater than 1, the local oscillator optical path includes a single-mode coupler, a first optical splitter, and N second optical splitters, the local oscillator optical path splits the first local oscillator light into at least two second local oscillator lights, and transmits each of the second local oscillator lights to each of the echo optical paths, including: The single-mode coupler transmits the first local oscillation light to the first optical splitter; The first optical splitter splits the first local oscillation light into N sixth local oscillation lights, and transmits each sixth local oscillation light to each second optical splitter; Each of the second optical splitters splits each of the sixth local oscillation lights into a second local oscillation light, a third local oscillation light, a fourth local oscillation light and a fifth local oscillation light, and transmits the second local oscillation light to the first mixer, transmits the third local oscillation light to the second mixer, transmits the fourth local oscillation light to the third mixer, and transmits the fifth local oscillation light to the fourth mixer; the second local oscillation light, the third local oscillation light, the fourth local oscillation light and the fifth local oscillation light are optical signals of the same mode; Each echo light path is used to transmit each first echo light, and is used to convert each first echo light into at least two second echo lights of a preset mode, and to determine at least two detection information of a detection target based on each second echo light and each second local oscillation light, including: In each echo light path, the few-mode coupler transmits the first echo light to the mode demultiplexer; The mode demultiplexer converts the first echo light into the second echo light, the third echo light, the fourth echo light, and the 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 of different modes respectively; The mode converter converts the third echo light into a sixth echo light, converts the fourth echo light into a seventh echo light, converts the fifth echo light into an eighth echo light, and transmits the second echo light to the first mixer, the sixth echo light to the second mixer, the seventh echo light to the third mixer, and the eighth echo light to the fourth mixer, wherein 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 first mixer performs mixing processing on the second local oscillator light and the second echo light to obtain first mixed light, and transmits the first mixed light to the first balanced detector; The second mixer performs 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 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 mixer performs 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; The first balanced detector obtains first detection information based on the first mixed frequency light; The second balanced detector obtains second detection information based on the second mixed frequency light; The third balanced detector obtains third detection information based on the third mixed frequency light; The fourth balanced detector obtains fourth detection information based on the fourth mixed-frequency light.

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