Integrated coaxial coherent transceiver structure

Abstract

The invention relates to an integrated coaxial coherent transceiving structure, which comprises a laser transmitting module, a free space optical isolator, a first depolarization splitting prism, a first polarization splitting prism and a second polarization splitting prism which are arranged along an optical path, the second depolarization splitting prism, the third polarization splitting prism, the fourth polarization splitting prism and the receiving module are arranged in the direction of local oscillator signal light; input signal light and local oscillator signal light are subjected to coherent frequency mixing at the second depolarization splitting prism, and enter four receiving modules through four emergent ports respectively. Self-coherent modulation and demodulation are carried out, so that the device can be suitable for 400G, 800G and 1.6 T coherent modulation and demodulation modules, FMCW laser radars and FSO free space laser communication; the structure formed by combining a plurality of prisms is small in size and can be made into a strip array structure, and integrated hybrid integration is facilitated.

Description

Technical Field

[0001] The invention relates to the field of optical technology, and in particular to an integrated coaxial coherent transceiver structure. Background Art

[0002] Lidar is a radar system that emits laser beams to detect the position, speed and other characteristic quantities of a target. Its working principle is to transmit a detection signal to the target, and then compare the received signal reflected from the target with the transmitted signal. After appropriate processing, relevant information about the target can be obtained, such as target distance, direction, height, speed, attitude, and even shape parameters.

[0003] For the laser radar system, its ranging principle is to emit a continuous wave with a linearly changing frequency as the outgoing signal within the sweep period. Part of the outgoing signal is used as the local oscillator signal, and the rest is emitted outward for detection. The echo signal returned after being reflected by the object has a certain frequency difference with the local oscillator signal. By measuring the frequency difference, the distance information between the detected target and the radar can be obtained.

[0004] At present, in FMCW laser radar systems, a circulator is often required to complete the transmission of the outgoing signal and the reception of the echo signal (for example, a coaxial transceiver laser radar and optical chip with patent publication number CN116413689A uses a circulator as a second optical coupler). The circulator often has insertion loss and strong echo interference, resulting in a low signal-to-noise ratio of the system or even the complete annihilation of the real intermediate frequency signal and the inability to demodulate, resulting in the inability to accurately measure the position information of the target object. At the same time, the FMCW laser radar system using a circulator is relatively complex in structure and large in size. FSO free space laser communication is a similar situation. It's just that the received signal is the transmission signal of another terminal. Summary of the invention

[0005] In order to solve the above problems in the prior art, the present invention provides an integrated coaxial coherent transceiver structure.

[0006] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0007] An integrated coaxial coherent transceiver structure comprises a laser emitting module, a free-space optical isolator and a first depolarizing beam splitter prism arranged along an optical path; the laser emitting module is used to emit a linearly polarized laser signal and couple it into the free-space optical isolator; the free-space optical isolator rotates the linearly polarized light by 45° and couples it into the first depolarizing beam splitter prism; the first depolarizing beam splitter prism divides the received laser signal into a main power light and a local oscillator signal light and emits them in different directions; a quarter-wave plate is arranged on the output optical path of the local oscillator signal light; the local oscillator signal light passes through the quarter-wave plate The main power light passes through the first polarization beam splitter prism and the second polarization beam splitter prism in sequence and then emerges as the emergent signal light; the input signal light passes through the second polarization beam splitter prism and the first polarization beam splitter prism in sequence and then couples into the second depolarization beam splitter prism; the local oscillator signal light and the input signal light are respectively incident from different ends of the second depolarization beam splitter prism; the emergent ends of the second depolarization beam splitter prism are respectively provided with the third polarization beam splitter prism and the fourth polarization beam splitter prism, so that the local oscillator signal light and the input signal light are respectively coupled into four receiving modules.

[0008] Furthermore, the laser emission module is an LD laser emission chip, or an external input signal light.

[0009] Furthermore, the splitting ratio of the main power light to the local oscillator signal light is 99.9:0.1 or 99.99:0.01 or 99:1.

[0010] Furthermore, the first polarization beam splitter prism includes a polarization beam splitter surface in the middle; a first reflection surface and a second reflection surface are respectively arranged in parallel on the upper and lower sides of the polarization beam splitter surface; the input signal light is reflected by the first reflection surface and then coupled into the second depolarization beam splitter prism.

[0011] Furthermore, the quarter wave plate is glued between the first depolarization beam splitter prism and the second depolarization beam splitter prism.

[0012] Furthermore, the third polarization splitting prism includes a polarization splitting surface, and a fourth reflection surface is arranged in parallel on the right side of the polarization splitting surface; the fourth polarization splitting prism includes a polarization splitting surface, and a fifth reflection surface is arranged in parallel above the polarization splitting surface.

[0013] Furthermore, the fourth reflecting surface and the fifth reflecting surface are arranged in close contact.

[0014] Furthermore, the receiving module includes a first PD receiving chip and a second PD receiving chip arranged at an output end of a third polarization beam splitter prism, and a third PD receiving chip and a fourth PD receiving chip arranged at an output end of a fourth polarization beam splitter prism.

[0015] Furthermore, two sixth reflection surfaces are provided at the output end of the third polarization beam splitter prism, so that the first PD receiving chip and the second PD receiving chip can be arranged on the same side of the third PD receiving chip.

[0016] Furthermore, the fourth polarization beam splitter prism and the third PD receiving chip and the fourth PD receiving chip form a balanced detector, or the third polarization beam splitter prism and the first PD receiving chip and the second PD receiving chip form a balanced detector.

[0017] The beneficial effects of the present invention are:

[0018] 1. The input signal light and the local oscillator signal light are coherently mixed at the second depolarization beam splitter prism and enter the four receiving modules through four output ports. Self-coherent modulation and modulation make it suitable for 400G, 800G, 1.6T related modulation and demodulation modules, FMCW laser radar, and FSO free space laser communication;

[0019] 2. Due to the high degree of structural integration of the present invention, it is easy to realize array arrangement, so it can be used for multi-channel FMCW laser radar;

[0020] 3. Furthermore, the structure formed by combining multiple prisms is small in size and can be made into a long strip array structure, which is conducive to integrated hybrid integration;

[0021] 4. The transmitting chip and receiving chip are used in a single transceiver system in a single row, and there is sufficient isolation between the LD transmitting chip and the PD receiving chip; after being arranged in multiple rows horizontally, they are suitable for multi-channel transceiver systems, reflecting higher integration value;

[0022] 5. The linear polarized light of the laser emission module is rotated 45° after passing through the free space optical isolator, and a small part is reflected by the first depolarization beam splitter prism. After passing through the quarter wave plate laterally, the two polarization states are introduced with a 90° phase shift, and are equally divided into two polarization states, P and S, on the polarization beam splitter prism, and contain a 90° phase shift. The present structure can easily and simply introduce the phase shift and simplify the structure. The waveguide in the prior art needs to realize the splitting, polarization splitting, and the phase shift introduction structure is complex, and multiple optical fiber devices need to be coupled. In addition, the waveguide cannot currently realize polarization splitting. After the polarization splitting is realized, it needs to be coupled and introduced into the waveguide, and then the optical path difference of the two branches is introduced to introduce the phase shift. The present invention not only effectively simplifies the optical path, but also the quarter wave plate can be glued between the first depolarization beam splitter prism and the second depolarization beam splitter prism, which greatly reduces the product size.

[0023] 6. The echo signal light returns along the same optical path as the outgoing signal, realizing coaxial transmission and reception, which can reduce interference light. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is a schematic diagram of the structure of the present invention;

[0026] Figure 2 It is a schematic diagram of another embodiment of the structure of the present invention;

[0027] Figure 3 It is a schematic diagram of another embodiment of the structure of the present invention;

[0028] Explanation of the accompanying drawings: 10, laser transmitting module; 11, first PD receiving chip; 12, second PD receiving chip; 13, third PD receiving chip; 14, fourth PD receiving chip; 20, free space optical isolator; 30, first depolarization beam splitter prism; 31, local oscillator signal light; 32, main power light; 33, output signal light; 34, input signal light; 40, first polarization beam splitter prism; 41, first reflection surface; 42, second reflection surface; 50, second polarization beam splitter prism; 51, third reflection surface; 60, quarter wave plate; 70, second depolarization beam splitter prism; 80, third polarization beam splitter prism; 81, fourth reflection surface; 82, sixth reflection surface; 90, fourth polarization beam splitter prism; 91, fifth reflection surface; 901, balanced detector. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0031] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] like Figure 1 As shown, an integrated coaxial coherent transceiver structure includes a laser emitting module 10, a free space optical isolator 20, and a first depolarizing beam splitter prism 30 arranged along an optical path; the arrangement along the optical path means the arrangement along the propagation direction of the laser. In this embodiment, the laser emitted by the laser emitting module 10 passes through the free space optical isolator 20 and the first depolarizing beam splitter prism 30 in sequence. The laser emitting module 10 is preferably an LD laser emitting chip in the present invention; the laser emitting module 10 is composed of various types of lasers, including but not limited to carbon dioxide lasers, neodymium-doped yttrium aluminum garnet lasers, semiconductor lasers, wavelength tunable solid lasers, and fiber frequency modulated lasers. In one embodiment of the present application, for the application of FMCW laser radar, a light source capable of achieving continuous frequency change is required, and its frequency sweep range usually covers hundreds of MHz to tens of GHz, and a triangular wave is often used for modulation, and the modulation frequency is generally set between 10kHz and 100kHz. In addition, FMCW LiDAR has strict requirements on the continuity and linearity of the transmitted signal to ensure that the difference between the local oscillator signal and the echo signal remains stable, thereby avoiding the introduction of other uncertainties due to nonlinear changes in the waveform. To meet these requirements, current-modulated distributed feedback (DFB) semiconductor lasers or external cavity semiconductor lasers (ECDL) can usually be selected as light sources.

[0033] The laser emission module 10 is used to emit a linearly polarized laser signal and couple it into a free-space optical isolator 20; the free-space optical isolator 20 rotates the linearly polarized light by 45° and couples it into a first depolarizing beam splitter prism 30; the first depolarizing beam splitter prism 30 divides the received laser model into a main power light 32 and a local oscillator signal light 31 and emits them in different directions, usually the main power light 32 and the local oscillator signal light 31 are emitted in mutually perpendicular directions; the splitting ratio of the main power light 32 to the local oscillator signal light 31 is 99.9:0.1, and in another embodiment, the splitting ratio can also be 99:1 or 9:1 or 99.99:0.01; a quarter wave plate 60 is provided on the output optical path of the local oscillator signal light 31; the local oscillator signal light 31 is coupled into a second depolarizing beam splitter prism 70 after passing through the quarter wave plate 60; the quarter wave plate 60 is mainly used to introduce a 90° phase shift, and can be glued between the first depolarizing beam splitter prism 30 and the second depolarizing beam splitter prism The main power light 32 passes through the first polarization beam splitter prism 40 and the second polarization beam splitter prism 50 in sequence and then emerges as an emergent signal light 33. The main power light 32 is split into two beams in the first polarization beam splitter prism 40. The first polarization beam splitter prism 40 includes a polarization beam splitting surface in the middle, which is used to split the main power light 32 into P polarized light and S polarized light. The upper and lower sides of the polarization beam splitting surface are respectively parallel to the first reflection surface 41 and the second reflection surface 42. The main power light 32 is split in the first polarization beam splitter prism 40 and then reflected by the second reflection surface 42, so that the two beams are incident on the second polarization beam splitter prism 50 in a parallel state, and are combined in the second polarization beam splitter prism 50 and emitted as an outgoing signal light 33; the second polarization beam splitter prism 50 also includes a polarization beam splitting surface in the middle, and a third reflection surface 51 is arranged parallel to the upper side of the polarization beam splitting surface; the light is emitted in a collimated manner, that is, the outgoing signal light 33 is emitted outward in an approximately parallel manner.

[0034] The input signal light 34 is incident coaxially into the second polarization beam splitter prism 50, and then is coupled into the second depolarization beam splitter prism 70 after being emitted from another emission direction through the first polarization beam splitter prism 40. The emission direction of the input signal light 34 is perpendicular to the direction of the main power light 32, so it will not return to the first depolarization beam splitter prism 30. The input signal light 34 is reflected by the first reflection surface 41 and then incident into the second depolarization beam splitter prism 70; thereby, the local oscillator signal light 31 and the input signal light 34 are incident from different ends of the second depolarization beam splitter prism 70 respectively; the emission ends of the second depolarization beam splitter prism 70 are respectively provided with a third polarization beam splitter prism 80 and a fourth polarization beam splitter prism 90, so that the local oscillator signal light 31 and the input signal light 34 are respectively coupled into four receiving modules;

[0035] In one embodiment, the third polarization beam splitter prism 80 includes a polarization beam splitting surface, and a fourth reflection surface 81 is provided in parallel to the right side of the polarization beam splitting surface; the fourth polarization beam splitter prism 90 includes a polarization beam splitting surface, and a fifth reflection surface 91 is provided in parallel above the polarization beam splitting surface; in one embodiment, the fourth reflection surface 81 and the fifth reflection surface 91 are arranged in close contact, so that the second depolarization beam splitter prism 70, the third polarization beam splitter prism 80, and the fourth polarization beam splitter prism 90 can form an integrated structure;

[0036] In one embodiment, the receiving module includes a first PD receiving chip 11 and a second PD receiving chip 12 disposed at the output end of the third polarization splitter prism 80 , and a third PD receiving chip 13 and a fourth PD receiving chip 14 disposed at the output end of the fourth polarization splitter prism 90 ;

[0037] like Figure 2 As shown, in one embodiment, the fourth polarization beam splitter prism 90 and the third PD receiving chip 13 and the fourth PD receiving chip 14 constitute a balanced detector 901; the fourth polarization beam splitter prism 90 may not be fixedly connected to the third polarization beam splitter prism 80; in another embodiment, the third polarization beam splitter prism 80 and the first PD receiving chip 11 and the second PD receiving chip 12 constitute a balanced detector;

[0038] like Figure 3 As shown, in one embodiment, the output end of the third polarization beam splitter prism 80 is provided with two sixth reflection surfaces 82, so that the first PD receiving chip 11 and the second PD receiving chip 12 can be arranged on the same side of the third PD receiving chip 13 to achieve same-side transmission and reception;

[0039] Based on the integrated advantages of the coaxial coherent transceiver structure of the present invention, it is convenient to set multiple transversely and / or longitudinally so that they can be arranged in the form of an array, which is suitable for a multi-channel transceiver system or a multi-channel FMCW laser radar;

[0040] Working principle: the linear polarized light emitted by the laser emitting module 10 is rotated 45° after passing through the free space optical isolator 20, and further enters the first depolarizing beam splitter prism 30. The first depolarizing beam splitter prism 30 splits the laser signal into two beams of light, namely the main power light 32 and the local oscillation signal light 31, which are emitted from the first depolarizing beam splitter prism 30 perpendicular to each other. Both beams of light contain linear polarized light in two polarization states, P and S. The first depolarizing beam splitter prism 30 keeps the original proportional relationship between the horizontal polarization and the vertical polarization in the incident light as much as possible, instead of separating them; so that the P polarization component and the S polarization component of the incident light have similar spectroscopic characteristics. This design helps to reduce the change in polarization state and maintain the original polarization state of the light; the first depolarization splitter prism 30 takes a lower proportion of the local oscillator signal light 31, and the splitting ratio of the main power light 32 to the local oscillator signal light 31 is 99.9:0.1; because the main power light 32 and the local oscillator signal light 31 are both obtained by splitting the same laser signal, the frequency change rules of the main power light 32 and the local oscillator signal light 31 are the same, and the frequency modulation frequencies are both linear.

[0041] The local oscillator signal light 31 passes through the quarter wave plate 60, and the two polarization states introduce a 90° phase shift, and are further divided into two paths in the second depolarization beam splitter prism 70, respectively traveling in the direction of the third polarization beam splitter prism 80 and the fourth polarization beam splitter prism 90. The splitting ratio of the second depolarization beam splitter prism 70 is 50:50. The third polarization beam splitter prism 80 and the fourth polarization beam splitter prism 90 further split the signal light into P polarization light and S polarization light, and then enter the four receiving modules respectively;

[0042] The main power light 32 is decomposed into linear polarized light after passing through the first polarization beam splitter prism 40, and is reflected by the second reflection surface 42 and the third reflection surface 51, and is output after being combined by the second polarization beam splitter prism 50; when the present invention is applied to a laser radar, the echo signal light returned by the outgoing signal light 33 when encountering an obstacle passes through the second polarization beam splitter prism 50 and the first polarization beam splitter prism 40 in sequence, and is coupled into the second depolarization beam splitter prism 70; the echo signal light is reflected by the first reflection surface 41 and is coupled into the second depolarization beam splitter prism 70, and the combined light emission direction of the echo signal light is perpendicular to the direction in which the main power light 32 is incident on the first polarization beam splitter prism 40; the echo signal light and the local oscillator signal light 31 are incident on the second depolarization beam splitter prism 70 from different ends of the second depolarization beam splitter prism 70 respectively, and the echo signal light is incident on the second depolarization beam splitter prism 70 from different ends of the second depolarization beam splitter prism 70. The signal light and the local oscillator signal light 31 are coherent in the second depolarization beam splitter prism 70; the echo signal light is further divided into two paths in the second depolarization beam splitter prism 70 and travels in the direction of the third polarization beam splitter prism 80 and the fourth polarization beam splitter prism 90 respectively. The splitting ratio of the second depolarization beam splitter prism 70 is 50:50. The third polarization beam splitter prism 80 and the fourth polarization beam splitter prism 90 further divide the signal light into P polarized light and S polarized light, and then enter the four receiving modules respectively; therefore, each receiving module contains two polarized lights with different phase shifts; if it is applied to FMCW laser radar, the obstacle reflected light is used to calculate the distance and speed through the frequency difference and Doppler frequency shift; if it is used as a coherent optical transceiver system, a quarter wave plate 60 is used to introduce a 90° phase shift of the two polarization states. Then another transmitting and receiving system transmits the received input signal light 34 (similar to the transmission optical path of the echo signal light), interferes and mixes with the local oscillator signal light 31, obtains the coherent mixed optical signal on the four receiving modules, and then performs complex coherent calculations to obtain the transmission optical signal;

[0043] In the present invention, the input signal light 34 represents different meanings according to the different systems in which it is applied. It can be the echo signal light returned by the outgoing signal light 33 when it encounters an obstacle, or it can be the input signal light 34 emitted by another transmitting system. The input signal light 34 is coaxially transmitted and received with the outgoing signal light 33. When the present invention is applied to FSO free space laser communication, the laser transmitting module 10 is the external input signal light.

[0044] The fourth polarization beam splitter prism 90 and the third PD receiving chip 13 and the fourth PD receiving chip 14 constitute a balanced detector, and obtain a pair of in-phase differential signals, so that the detection sensitivity is doubled, or the transmission distance is doubled; it should be noted that the balanced detector in the present invention is composed of relevant components in the structure itself, not a separate newly added structure, which can not only save costs, but also ensure functionality while being highly integrated; that is, the third PD receiving chip 13 and the fourth PD receiving chip 14 can cooperate with the fourth polarization beam splitter prism 90 to achieve the effect of a balanced detector while acting as a receiving module; in practical applications, the coaxial coherent transceiver structure of the present invention will be used together with a mediation module, which includes a data acquisition card and a signal analysis device. In the present invention, the balanced detector composed of the fourth polarization beam splitter prism 90 and the third PD receiving chip 13 and the fourth PD receiving chip 14 is responsible for converting the received in-phase differential signal pair into electrical signals, and then transmitting these signals to the data acquisition card. The data acquisition card is connected to the signal analysis device and is responsible for processing and solving the received signals.

[0045] In order to reduce noise interference and improve measurement accuracy, it is necessary to filter out the noise components (such as stray light) in the in-phase differential signal pair, which can usually be achieved through a signal filter. After the noise is filtered out, a light detector is used to detect the signal. In an embodiment of the present application, a balanced detector is used for detection. By using its coherent detection technology, the receiving sensitivity of the light detector can be increased by about 20dB compared to the traditional direct detection technology, thereby significantly reducing the impact of detector noise and electronic circuit noise on the detection of weak light signals.

[0046] The data acquisition process refers to automatically acquiring the analog or digital signal (i.e., the detected intermediate frequency signal) of the device through the data acquisition card, and transmitting it to the host computer for further analysis and processing, and finally realizing the measurement of the distance of the detected target. It should be noted that in the embodiments of the present application, the configuration of the data acquisition and processing system will be determined according to the actual performance requirements of the system. Generally speaking, the real-time system needs to be equipped with a high-speed data acquisition card.

[0047] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An integrated coaxial coherent transceiver structure, characterized in that: The invention comprises a laser emission module (10), a free-space optical isolator (20), and a first depolarizing beam splitter prism (30) arranged along an optical path; the laser emission module (10) is used to emit a linearly polarized laser signal and couple it into the free-space optical isolator (20); the free-space optical isolator (20) rotates the linearly polarized light by 45 degrees and couples it into the first depolarizing beam splitter prism (30); the first depolarizing beam splitter prism (30) divides the received laser signal into main power light (32) and local oscillator signal light (31) and emits them in different directions; a quarter-wave plate (60) is arranged on the emission optical path of the local oscillator signal light (31); the local oscillator signal light (31) passes through the quarter-wave plate (60) and couples it into the second A depolarizing beam splitter prism (70); the main power light (32) passes through the first polarizing beam splitter prism (40) and the second polarizing beam splitter prism (50) in sequence and then emerges as an emergent signal light; the input signal light (34) passes through the second polarizing beam splitter prism (50) and the first polarizing beam splitter prism (40) in sequence and then is coupled into the second depolarizing beam splitter prism (70); the local oscillator signal light (31) and the input signal light (34) are respectively incident from different ends of the second depolarizing beam splitter prism (70); and the emergent ends of the second depolarizing beam splitter prism (70) are respectively provided with a third polarizing beam splitter prism (80) and a fourth polarizing beam splitter prism (90), so that the local oscillator signal light (31) and the input signal light (34) are respectively coupled into four receiving modules.

2. The integrated coaxial coherent transceiver structure according to claim 1, characterized in that: The laser emission module (10) is an LD laser emission chip, or external input signal light.

3. The integrated coaxial coherent transceiver structure according to claim 1, characterized in that: The splitting ratio of the main power light (32) to the local oscillation signal light (31) is 99.9:0.1 or 99.99:0.01 or 99:

1.

4. The integrated coaxial coherent transceiver structure according to claim 1, characterized in that: The first polarization beam splitter prism (40) comprises a polarization beam splitter surface in the middle, and a first reflection surface (41) and a second reflection surface (42) are respectively arranged in parallel on the upper and lower sides of the polarization beam splitter surface; the input signal light (34) is reflected by the first reflection surface (41) and then coupled into the second depolarization beam splitter prism (70); the second polarization beam splitter prism (50) comprises a polarization beam splitter surface in the middle, and a third reflection surface (51) is arranged in parallel above the polarization beam splitter surface.

5. The integrated coaxial coherent transceiver structure according to claim 1, characterized in that: The quarter wave plate (60) is glued between the first depolarizing beam splitter prism (30) and the second depolarizing beam splitter prism (70).

6. The integrated coaxial coherent transceiver structure according to claim 1, characterized in that: The third polarization beam splitting prism (80) comprises a polarization beam splitting surface, and a fourth reflection surface (81) is arranged in parallel on the right side of the polarization beam splitting surface; the fourth polarization beam splitting prism (90) comprises a polarization beam splitting surface, and a fifth reflection surface (91) is arranged in parallel above the polarization beam splitting surface.

7. The integrated coaxial coherent transceiver structure according to claim 6, characterized in that: The fourth reflecting surface (81) and the fifth reflecting surface (91) are arranged in close contact.

8. The integrated coaxial coherent transceiver structure according to claim 1, characterized in that: The receiving module comprises a first PD receiving chip (11) and a second PD receiving chip (12) arranged at the output end of a third polarization beam splitter prism (80), and a third PD receiving chip (13) and a fourth PD receiving chip (14) arranged at the output end of a fourth polarization beam splitter prism (90).

9. The integrated coaxial coherent transceiver structure according to claim 8, characterized in that: The output end of the third polarization beam splitting prism (80) is provided with two sixth reflection surfaces (82), so that the first PD receiving chip (11) and the second PD receiving chip (12) can be arranged on the same side of the third PD receiving chip (13).

10. The integrated coaxial coherent transceiver structure according to claim 8, characterized in that: The fourth polarization beam splitter prism (90) and the third PD receiving chip (13) and the fourth PD receiving chip (14) form a balanced detector, or the third polarization beam splitter prism (80) and the first PD receiving chip (11) and the second PD receiving chip (12) form a balanced detector.

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