An optical module

Abstract

The application discloses an optical module, comprising: a receiving optical fiber, receiving vortex receiving light. A vortex mode demultiplexing module is connected with the receiving optical fiber, used for splitting and converting the first sub-receiving signal light and the receiving pilot light into Gaussian mode. A first coherent receiver is connected with the first output port of the vortex mode demultiplexing module through the first input port, and connected with the second output port of the vortex mode demultiplexing module through the second input port, used for mixing and detecting the sub-receiving signal light and the first sub-pilot light into the first electrical signal. The application obtains the Gaussian mode receiving pilot light and the receiving signal light by demultiplexing the vortex receiving light, and the receiving pilot light is used as the local oscillator light to realize self-homodyne coherent transmission, eliminating the influence of frequency offset and phase noise, without complex carrier recovery algorithm, reducing the complexity, power consumption and cost of the coherent detection system, and breaking through the limitations of high power consumption, high complexity and high cost of the traditional coherent detection.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of communication technology, and in particular to an optical module. BACKGROUND

[0002] The rapid development of emerging high-speed data communication services leads to exponential growth of global data traffic, and typical short and medium distance optical communication such as data center and metropolitan area network is facing huge network traffic pressure. At present, the intensity modulation / direct detection scheme is widely used in short and medium distance optical communication. This scheme has low cost and can effectively control the cost of the communication system. However, the intensity modulation / direct detection scheme cannot utilize the phase information of the optical carrier, wastes the spectrum resource, and the communication capacity and spectrum efficiency are too small to cope with the current explosive growth of communication data.

[0003] Coherent optical communication modulates the amplitude and phase of the optical carrier, and the receiving end uses a local oscillator to mix the signal optical carrier to realize balanced detection for demodulation. Coherent optical communication fully utilizes the amplitude and phase dimension resources of the optical wave, and has the advantages of large transmission capacity, high receiving sensitivity, and compatibility with various advanced modulation formats compared with the intensity modulation / direct detection scheme. On the other hand, coherent optical communication can be combined with wavelength division multiplexing, polarization multiplexing, time division multiplexing, and space division multiplexing technology to fully utilize the various dimensions of the optical wave and further improve the overall transmission capacity and spectrum efficiency. The mode division multiplexing technology utilizes multiple mutually orthogonal spatial modes to transmit information in parallel, which is an important part of the space division multiplexing technology. Optical vortex modes with different topological charge numbers are mutually orthogonal, and there are theoretically infinite topological charge numbers, which provides a very promising scheme for improving communication capacity due to the diversity of values. The combination of coherent optical communication and vortex mode multiplexing technology can greatly improve the system communication capacity in short and medium distance optical interconnection.

[0004] Traditional coherent optical communication requires the use of high-performance lasers with stable wavelength and narrow linewidth. The cost of the laser is very high, and the frequency offset between the signal light and the local oscillator light and the phase noise of the laser cause great damage to the signal during coherent detection. The receiving end digital signal processing requires complex frequency offset compensation and carrier phase recovery algorithms. The coherent optical communication structure is complex, and expensive devices are required, and the system complexity, power consumption and cost are high. However, the short and medium distance optical interconnection in the data center requires low complexity, low power consumption and low cost of the communication system. SUMMARY

[0005] The present application provides an optical module to improve the communication rate of the optical module.

[0006] To solve the above technical problems, the embodiments of the present application disclose the following technical solutions:

[0007] The embodiment of the present application discloses an optical module, comprising:

[0008] A receiving optical fiber receives vortex receiving light, the vortex receiving light is a mixed vortex light of a first sub-receiving signal light and a receiving pilot light, the first sub-receiving signal light and the receiving pilot light have different vortex modes;

[0009] A vortex mode demultiplexing module is connected to the input end of the receiving optical fiber, and is used for splitting the first sub-receiving signal light and the receiving pilot light and converting them into Gaussian modes;

[0010] A first coherent receiver is connected to the first output port of the vortex mode demultiplexing module through a first input port, and is connected to the second output port of the vortex mode demultiplexing module through a second input port, and is used for mixing and detecting the sub-receiving signal light and the first sub-pilot light to convert them into a first electrical signal.

[0011] Beneficial effects:

[0012] The present application discloses an optical module, which realizes self-homodyne coherent optical communication, comprising: a receiving optical fiber receives vortex receiving light, the vortex receiving light is a mixed vortex light of a first sub-receiving signal light and a receiving pilot light, the first sub-receiving signal light and the receiving pilot light have different vortex modes. A vortex mode demultiplexing module is connected to the input end of the receiving optical fiber, and is used for splitting the first sub-receiving signal light and the receiving pilot light and converting them into Gaussian modes. A first coherent receiver is connected to the first output port of the vortex mode demultiplexing module through a first input port, and is connected to the second output port of the vortex mode demultiplexing module through a second input port, and is used for mixing and detecting the sub-receiving signal light and the first sub-pilot light to convert them into a first electrical signal. The present application obtains Gaussian mode receiving pilot light and receiving signal light by demultiplexing the vortex receiving light, and uses the receiving pilot light as a local oscillator to realize self-homodyne transmission, eliminates the influence of frequency offset and phase noise, does not need a complex carrier recovery algorithm, reduces the complexity, power consumption and cost of the coherent detection system, and breaks through the limitations of high power consumption, high complexity and high cost of traditional coherent detection. BRIEF DESCRIPTION OF DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the present disclosure, the following will briefly introduce the drawings needed to be used in some embodiments of the present disclosure. Obviously, the drawings in the following description are only some drawings of the embodiments of the present disclosure, and other drawings can also be obtained by those skilled in the art according to these drawings. In addition, the drawings in the following description can be regarded as schematic diagrams, and are not limited to the actual size, actual process, actual time sequence, etc. of the products involved in the embodiments of the present disclosure.

[0014] Figure 1 This is a connection diagram of an optical communication system according to some embodiments;

[0015] Figure 2 This is a structural diagram of an optical network terminal according to some embodiments;

[0016] Figure 3 This is a structural diagram of an optical module according to some embodiments;

[0017] Figure 4 An exploded view of an optical module according to some embodiments;

[0018] Figure 5 This is a schematic diagram of a light emitting component structure shown in an embodiment of this application;

[0019] Figure 6 This is a schematic diagram of the optical path of an optical emitting component according to an embodiment of this application;

[0020] Figure 7 This is a schematic diagram of a vortex mode multiplexing module structure shown in an embodiment of this application;

[0021] Figure 8 A schematic diagram of a vortex ring fiber cross-section provided in an embodiment of this application;

[0022] Figure 9 This application embodiment shows a schematic diagram of another vortex mode multiplexing module;

[0023] Figure 10 This is a schematic diagram of an optical receiving component structure shown in an embodiment of this application;

[0024] Figure 11 This is a schematic diagram of a light receiving component according to an embodiment of this application;

[0025] Figure 12 This is a schematic diagram of a vortex mode demultiplexing module structure shown in an embodiment of this application;

[0026] Figure 13 This is a schematic diagram of another vortex mode demultiplexing module shown in an embodiment of this application;

[0027] Figure 14 This application provides a schematic diagram of a self-zero difference coherent detection system structure.

[0028] Figure 15 This application provides a schematic diagram of a pilot optical path and signal optical path length alignment module for self-zero difference coherent detection based on vortex mode multiplexing. Detailed Implementation

[0029] In the following, the technical solutions in the embodiments of the present disclosure will be described clearly and completely with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, but not all the embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by a person of ordinary skill in the art belong to the scope of protection of the present disclosure.

[0030] Unless otherwise required by context, the term "comprise" and its other forms such as "comprises" and "comprising" are to be construed as open-ended, i.e. as "including, but not limited to", in the description and the claims. In the description, the terms "one embodiment", "some embodiments", "exemplary embodiments", "example", "specific example" or "some examples" are not necessarily referring to the same embodiment or example. Furthermore, the described features, structures, materials or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0031] In the following, the terms "first", "second", etc. are used only for the purpose of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the embodiments of the present disclosure, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0032] In describing some embodiments, "coupled" and "connected", and their derivatives, can be used. For example, the term "connected" can be used in describing some embodiments to indicate that two or more components are in direct physical or electrical contact with each other. For another example, the term "coupled" can be used in describing some embodiments to indicate that two or more components are in direct physical or electrical contact with each other. However, the term "coupled" or "communicatively coupled" can also mean that two or more components are not in direct contact with each other, but still cooperate or interact with each other. The embodiments disclosed herein are not necessarily limited to the content herein.

[0033] "A, B, and C at least one of" has the same meaning as "at least one of A, B, or C", both including the following combinations of A, B, and C: only A, only B, only C, a combination of A and B, a combination of A and C, a combination of B and C, and a combination of A, B, and C.

[0034] "A and / or B" includes the following three combinations: only A, only B, and a combination of A and B.

[0035] The use of "adapted for" or "configured for" herein means open and inclusive language that does not exclude devices adapted for or configured for performing additional tasks or steps.

[0036] As used herein, "about", "approximately" or "approximately" includes the stated value and the average value within an acceptable deviation range of the specific value, wherein the acceptable deviation range is determined by the person of ordinary skill in the art considering the measurement being discussed and the error related to the measurement of the specific quantity (i.e. the limitations of the measurement system).

[0037] In optical communication technology, light is used to carry information to be transmitted, and the optical signal carrying information is transmitted to an information processing device such as a computer through an information transmission device such as an optical fiber or an optical waveguide to complete the transmission of information. Because the optical signal has passive transmission characteristics when transmitted through the optical fiber or the optical waveguide, low-cost, low-loss information transmission can be achieved. In addition, the signal transmitted by the information transmission device such as the optical fiber or the optical waveguide is an optical signal, and the signal that the information processing device such as the computer can recognize and process is an electrical signal, so in order to establish an information connection between the information transmission device such as the optical fiber or the optical waveguide and the information processing device such as the computer, it is necessary to realize the mutual conversion between the electrical signal and the optical signal.

[0038] The optical module realizes the mutual conversion function of the optical signal and the electrical signal in the field of optical fiber communication technology. The optical module includes an optical port and an electrical port. The optical module realizes optical communication with the information transmission device such as the optical fiber or the optical waveguide through the optical port, and realizes electrical connection between the optical network terminal (for example, an optical modem) through the electrical port. The electrical connection is mainly used to realize power supply, I2C signal transmission, data signal transmission, and grounding; the optical network terminal transmits the electrical signal to the information processing device such as the computer through the network cable or the wireless fidelity technology (Wi-Fi).

[0039] Figure 1 A connection relationship diagram of an optical communication system according to some embodiments. As shown in Figure 1 The optical communication system mainly includes a remote server 1000, a local information processing device 2000, an optical network terminal 100, an optical module 200, an optical fiber 101, and a network cable 103.

[0040] One end of the optical fiber 101 is connected to the remote server 1000, and the other end is connected to the optical network terminal 100 through the optical module 200. The optical fiber itself can support long-distance signal transmission, for example, signal transmission of thousands of meters (6-8 kilometers), and theoretically, super-long distance transmission can be achieved if a repeater is used. Therefore, in a general optical communication system, the distance between the remote server 1000 and the optical network terminal 100 can usually reach thousands of meters, tens of kilometers, or hundreds of kilometers.

[0041] One end of the network cable 103 is connected to the local information processing device 2000, and the other end is connected to the optical network terminal 100. The local information processing device 2000 can be any one or several of the following devices: a router, a switch, a computer, a mobile phone, a tablet computer, a television, etc.

[0042] The physical distance between the remote server 1000 and the optical network terminal 100 is greater than the physical distance between the local information processing device 2000 and the optical network terminal 100. The connection between the local information processing device 2000 and the remote server 1000 is completed by the optical fiber 101 and the network cable 103; and the connection between the optical fiber 101 and the network cable 103 is completed by the optical module 200 and the optical network terminal 100.

[0043] The optical module 200 includes an optical port and an electrical port. The optical port is configured to be connected to the optical fiber 101, so that the optical module 200 and the optical fiber 101 establish a bidirectional optical signal connection; the electrical port is configured to access the optical network terminal 100, so that the optical module 200 and the optical network terminal 100 establish a bidirectional electrical signal connection. The optical module 200 realizes the mutual conversion between optical signals and electrical signals, thereby establishing a connection between the optical fiber 101 and the optical network terminal 100. For example, the optical signal from the optical fiber 101 is converted into an electrical signal by the optical module 200 and input into the optical network terminal 100, and the electrical signal from the optical network terminal 100 is converted into an optical signal by the optical module 200 and input into the optical fiber 101.

[0044] The optical network terminal 100 comprises a housing in the shape of a cuboid, and an optical module interface 102 and a network cable interface 104 arranged on the housing. The optical module interface 102 is configured to access the optical module 200, so that the optical network terminal 100 and the optical module 200 establish a bidirectional electrical signal connection. The network cable interface 104 is configured to access the network cable 103, so that the optical network terminal 100 and the network cable 103 establish a bidirectional electrical signal connection. The optical module 200 and the network cable 103 establish a connection through the optical network terminal 100. For example, the optical network terminal 100 transmits electrical signals from the optical module 200 to the network cable 103, and transmits signals from the network cable 103 to the optical module 200, so that the optical network terminal 100, as a host of the optical module 200, can monitor the operation of the optical module 200. The host of the optical module 200 can also include an optical line terminal (OLT) in addition to the optical network terminal 100.

[0045] The remote server 1000 establishes a bidirectional signal transmission channel with the local information processing device 2000 through the optical fiber 101, the optical module 200, the optical network terminal 100, and the network cable 103.

[0046] Figure 2 FIG. 1 is a structural diagram of an optical network terminal according to some embodiments, for clearly showing the connection relationship between the optical module 200 and the optical network terminal 100, Figure 2 Only the structure of the optical network terminal 100 related to the optical module 200 is shown. As Figure 2 indicated, the optical network terminal 100 further comprises a PCB circuit board 105 arranged in the housing, a cage 106 arranged on the surface of the PCB circuit board 105, and an electrical connector arranged inside the cage 106. The electrical connector is configured to access the electrical port of the optical module 200. The heat sink 107 has a fin or other protruding part that increases the heat dissipation area.

[0047] The optical module 200 is inserted into the cage 106 of the optical network terminal 100, and the optical module 200 is fixed by the cage 106. The heat generated by the optical module 200 is conducted to the cage 106, and then diffused through the heat sink 107. After the optical module 200 is inserted into the cage 106, the electrical port of the optical module 200 is connected to the electrical connector inside the cage 106, so that the optical module 200 and the optical network terminal 100 establish a bidirectional electrical signal connection. In addition, the optical port of the optical module 200 is connected to the optical fiber 101, so that the optical module 200 and the optical fiber 101 establish a bidirectional electrical signal connection.

[0048] Figure 3 FIG. 2 is a structural diagram of an optical module according to some embodiments, Figure 4 FIG. 3 is an exploded view of an optical module according to some embodiments. As Figure 3and Figure 4 As shown in the figure, the optical module 200 comprises a housing, a circuit board 300 arranged in the housing, and an optical transceiver assembly.

[0049] The housing comprises an upper housing 201 and a lower housing 202, the upper housing 201 is covered on the lower housing 202 to form the above-mentioned housing with two openings 204 and 205; the outer contour of the housing generally presents a square body.

[0050] In some embodiments of the present disclosure, the lower housing 202 comprises a bottom plate and two lower side plates arranged perpendicularly to the bottom plate on both sides of the bottom plate; the upper housing 201 comprises a cover plate and two upper side plates arranged perpendicularly to the cover plate on both sides of the cover plate, the two side walls are combined with the two side plates to realize the covering of the upper housing 201 on the lower housing 202.

[0051] The direction of the line connecting the two openings 204 and 205 can be consistent with the length direction of the optical module 200, or can be inconsistent with the length direction of the optical module 200. For example, the opening 204 is located at the end of the optical module 200 (the left end of the figure), and the opening 205 is also located at the end of the optical module 200 (the right end of the figure). Alternatively, the opening 204 is located at the end of the optical module 200, and the opening 205 is located at the side of the optical module 200. Among them, the opening 204 is an electrical port, and the gold fingers of the circuit board 300 extend out of the electrical port 204 and are inserted into the upper computer (such as the optical network terminal 100); the opening 205 is an optical port, which is configured to access the external optical fiber 101, so that the optical fiber 101 is connected to the optical transceiver assembly inside the optical module 200. Figure 3 Figure 3 The assembly mode of combining the upper housing 201 and the lower housing 202 facilitates the installation of the circuit board 300, the optical transceiver assembly and other devices into the housing, and the upper housing 201 and the lower housing 202 can form encapsulation protection for these devices. In addition, when assembling the circuit board 300 and other devices, the deployment of the positioning components, heat dissipation components and electromagnetic shielding components of these devices is facilitated, which is conducive to the implementation of automated production.

[0052] In some embodiments, the upper housing 201 and the lower housing 202 are generally made of metal materials, which is conducive to realizing electromagnetic shielding and heat dissipation.

[0053] In some embodiments, the optical module 200 further comprises an unlocking component 203 located on the outer wall of the housing of the optical module 200, the unlocking component 203 is configured to realize the fixed connection between the optical module 200 and the upper computer, or to release the fixed connection between the optical module 200 and the upper computer.

[0054] In some embodiments, the optical module 200 further comprises an unlocking component 203 located on the outer wall of the housing of the optical module 200, the unlocking component 203 is configured to realize the fixed connection between the optical module 200 and the upper computer, or to release the fixed connection between the optical module 200 and the upper computer.

[0055] ​For example, the unlocking component 203 is located on the outer wall of the two lower side plates 2022 of the lower shell 202, and includes a clamping component matched with the cage of the upper host (for example, the cage 106 of the optical network terminal 100). When the optical module 200 is inserted into the cage of the upper host, the optical module 200 is fixed in the cage of the upper host by the clamping component of the unlocking component 203. When the unlocking component 203 is pulled, the clamping component of the unlocking component 203 moves, thereby changing the connection relationship between the clamping component and the upper host, so as to release the clamping relationship between the optical module 200 and the upper host, and the optical module 200 can be pulled out of the cage of the upper host.

[0056] The circuit board 300 includes circuit traces, electronic components and chips, and the electronic components and chips are connected together according to circuit design through the circuit traces to realize power supply, electrical signal transmission and grounding functions. The electronic components may, for example, include capacitors, resistors, transistors, metal oxide semiconductor field effect transistors (MOSFETs). The chips may, for example, include microcontroller units (MCUs), limiting amplifiers, clock and data recovery chips (CDRs), power management chips, digital signal processing (DSP) chips.

[0057] The circuit board 300 is generally a hard circuit board. Due to its relatively hard material, the hard circuit board can also realize a bearing function, such as the hard circuit board can stably bear the chips; the hard circuit board can also be inserted into the electrical connector in the cage of the upper host.

[0058] The circuit board 300 further includes a gold finger 301 formed on the surface of the end thereof, and the gold finger 301 is composed of a plurality of pins independent of each other. The circuit board 300 is inserted into the cage 106, and the gold finger 301 is in conductive connection with the electrical connector in the cage 106. The gold finger 301 can be arranged only on the surface (for example, the upper surface shown) of one side of the circuit board 300, or can be arranged on the surfaces of the upper and lower sides of the circuit board 300 to adapt to occasions with a large number of pins. The gold finger 301 is configured to establish electrical connection with the upper host to realize power supply, grounding, I2C signal transmission, data signal transmission, etc. Of course, flexible circuit boards are also used in some optical modules. The flexible circuit board is generally used in cooperation with the hard circuit board to serve as a supplement to the hard circuit board. Figure 4 The gold finger 301 is configured to establish electrical connection with the upper host to realize power supply, grounding, I2C signal transmission, data signal transmission, etc. Of course, flexible circuit boards are also used in some optical modules. The flexible circuit board is generally used in cooperation with the hard circuit board to serve as a supplement to the hard circuit board.

[0059] The optical transceiver assembly includes an optical transmitting assembly and an optical receiving assembly.

[0060] Figure 5 A schematic diagram of an optical transmitting assembly structure is shown in an embodiment of the present application, as shown in Figure 5 To improve the optical communication capacity, the optical transmitting assembly provided by the present application comprises: a first laser 401, a first coupler 402 arranged at the light emitting end of the first laser 401. The first coupler 402 is provided with a plurality of output ports, including a first output port, a second output port and a third output port. A first modulator 403 is connected to the first output port of the first coupler 402, and a second modulator 404 is connected to the second output port of the first coupler 402. A vortex mode multiplexing module 406 is connected to the first modulator 403, the second modulator 404 and the third output port of the first coupler 402, respectively, to convert the signal light into vortex mode and multiplex it into a bundle. In the present application, the first modulator and the second modulator load data on the signal light, and the light output by the third output port is used as pilot light. The transmitting light is converted into vortex light with different angular momenta by the vortex mode multiplexing module 406, and the signal light and the pilot light are transmitted by different vortex mode channels. The pilot light received at the receiving end is used as a local oscillator to realize self-homodyne coherent detection, which eliminates the influence of frequency offset and phase noise, and does not require complex carrier recovery algorithm, thereby reducing the complexity, power consumption and cost of the coherent detection system, and breaking through the limitations of high power consumption, high complexity and high cost of traditional coherent detection.

[0061] Figure 6 A schematic diagram of the optical path of an optical transmitting assembly is shown in an embodiment of the present application, as shown in Figure 6 The first laser 401 is used to emit first transmitting light as a light source. The first coupler 402 is used to divide the first transmitting light into multiple paths. In the present application, the first coupler 402 is provided with three output ends, i.e., a first output port, a second output port and a third output port, to divide the first transmitting light into three paths as signal light or pilot light. The first output port outputs first sub-transmitting light, the second output port outputs second sub-transmitting light, and the third output port outputs third sub-transmitting light. The first sub-transmitting light and the second sub-transmitting light are used as signal light, and the third sub-transmitting light is used as first pilot light.

[0062] The first modulator 403 receives the first sub-transmitting light and modulates the first sub-transmitting light to generate first sub-signal light, wherein the first sub-signal light carries a first data signal. The second modulator 404 receives the second sub-transmitting light and modulates the second sub-transmitting light to generate second sub-signal light, wherein the second sub-signal light carries a second data signal. In the figure, the solid line represents Gaussian mode light, the dashed line represents vortex mode light, and the arrow represents the propagation direction of the light.

[0063] Further, the third output port of the first coupler 402 is connected with the optical fiber extension line 405, so that the pilot light path is equal to the signal light path, the influence of frequency offset and phase noise is eliminated, the signal light and the pilot light have the same phase change amount, and the system complexity, power consumption and cost are reduced.

[0064] The vortex mode multiplexing module 406 receives the first sub-signal light, the second sub-signal light and the pilot light, converts the first sub-signal light, the second sub-signal light and the first pilot light into different vortex modes and multiplexes them to generate the first vortex emission light signal. Specifically, the vortex mode multiplexing module 406 is provided with a first input port connected with the output end of the first modulator 403 to receive the first sub-signal light, a second input port connected with the output end of the second modulator 404 to receive the second sub-signal light, and a third input port connected with the third output port of the first coupler 402 to receive the first pilot light.

[0065] The output end of the vortex mode multiplexing module 406 is connected with the first emission optical fiber 407, and the first vortex emission signal light is sent out through the first optical fiber.

[0066] In the embodiment of the present application, the first emission optical fiber 407 is a vortex ring optical fiber.

[0067] Figure 7 A vortex mode multiplexing module structure diagram is shown in the embodiment of the present application, as shown in Figure 7 The vortex mode multiplexing module 406 is a free-space optical device vortex mode multiplexing module 406, which includes a collimator, a polarizer, a spatial light modulator, a beam combiner and a converging lens. The collimator collimates the Gaussian signal light in the single-mode optical fiber to output to the free space, the polarizer is used to adjust the polarization direction of the Gaussian signal light to the polarization direction of the spatial light modulator, the spatial light modulator is used to convert the Gaussian light into vortex mode, the beam combiner is used to multiplex the two generated vortex modes, and the converging lens is used to couple the free-space multiplexed vortex mode into the first emission optical fiber.

[0068] Specifically, the first collimator 4061 is arranged on the light path of the first sub-signal light and used to collimate the first sub-signal light. The first polarizer 4062 is arranged between the first spatial light modulator 4063 and the first collimator 4061 and used to adjust the polarization direction of the first sub-signal light to the working direction of the first spatial light modulator 4063. The first sub-signal light passes through the modulation of the first spatial light modulator 4063 to generate the first sub-vortex light.

[0069] The second collimator 4065 is arranged on the light path of the second sub-signal light, and is configured to collimate the second sub-signal light. The second polarizer 4066 is arranged between the second spatial light modulator 4067 and the second collimator 4065, and is configured to adjust the polarization direction of the second sub-signal light to the working direction of the second spatial light modulator 4067. The second sub-signal light passes through the modulation of the second spatial light modulator 4067, and generates second sub-vortex light.

[0070] The third collimator 4069 is arranged on the light path of the first pilot light, and is configured to collimate the first pilot light. The third polarizer 40610 is arranged between the third spatial light modulator 40611 and the third collimator, and is configured to adjust the polarization direction of the first pilot light to the working direction of the third spatial light modulator 40611. The first pilot light passes through the modulation of the third spatial light modulator 40611, and generates first pilot vortex light.

[0071] The first beam combiner 4068 is arranged on the light paths of the first spatial light modulator 4063 and the second spatial light modulator 4067, and is configured to combine the first sub-vortex light and the second sub-vortex light into first vortex signal light.

[0072] The first beam combiner 4068 reflects the first sub-vortex light and transmits the second sub-vortex light, so that the first sub-vortex light and the second sub-vortex light are combined into one beam of light after passing through the first beam combiner 4068.

[0073] The second beam combiner 40612 is arranged on the light paths of the third spatial light modulator 40611 and the first beam combiner 4068, and is configured to combine the first vortex signal light and the first pilot vortex light into first vortex emission light.

[0074] The first sub-signal light, the second sub-signal light, and the first pilot light pass through the vortex mode multiplexing module 406, and are converted into vortex modes and multiplexed to generate the first vortex emission light.

[0075] In some embodiments of the present application, the first coupler 402 specifically divides the first emission light into several paths, which can be set according to actual needs, and can be 3 paths as shown in the present application, or 4 paths, 5 paths, or other paths.

[0076] The spatial light modulator provided in the embodiments of the present application is a reflective spatial light modulator, and the included angle between the input light path and the output light path is as small as possible.

[0077] In some embodiments of the present application, the vortex mode used for transmitting the first pilot light can be a 0-order vortex mode, a 1-order vortex mode, or other order vortex modes.

[0078] In order to reduce the crosstalk between the signal light and the first pilot light, the signal light and the first pilot light use vortex modes of different orders in the vortex ring fiber for multiplexing transmission, and the crosstalk between the vortex modes used is less than -15 dB, which helps to improve the communication quality.

[0079] Figure 8 A vortex ring fiber cross section schematic diagram is provided for the embodiments of the present application. As shown in the figure, in some embodiments of the present application, the vortex ring fiber includes a central region 601, a ring core 602, and a cladding 603. The cladding is designed with fluorine doping, the refractive index of the cladding is lower than that of silica, and the relative refractive index difference between the cladding and silica is not more than 0.7%. The refractive index of the central region is the same as that of the cladding. The relative refractive index difference between the refractive index of the ring core and that of the cladding is not more than 1%. The refractive index of the core is greater than that of the cladding. The inner diameter of the ring core region is 2-10 μm, and the width is 1-20 μm. The vortex ring fiber only supports multi-channel radial first-order vortex modes and is divided into different mode groups. The first mode group has 2 modes, and each of the other mode groups has 4 modes. The effective refractive index difference between the remaining mode groups is >10 -4 .

[0080] Because the beam after beam combining is large, in some embodiments of the present application, the light emitting assembly is also provided with a first converging lens 40613 arranged on the exit light path of the second beam combiner 40612, for converging the first vortex emitted light to the first emitting fiber 407, and transmitting to the opposite end optical module. The converging beam of the first converging lens 40613 is located on the end face of the first emitting fiber 407, which improves the communication accuracy.

[0081] Figure 9 Another structure schematic diagram of a vortex mode multiplexing module is shown in the embodiments of the present application. As shown in the figure, the present application also provides another vortex mode multiplexing module, which includes:

[0082] A first single-mode fiber 40620 is connected at one end to the output end of the first modulator 403 and at the other end to one end of a first vortex ring fiber 40621, which excites a first vortex mode OAM 01 in the vortex ring fiber to convert the first sub-signal light into first sub-vortex light. A second single-mode fiber 40622 is connected at one end to the output end of the second modulator 404 to transmit the second sub-signal light. A first tapered coupler 40623 is connected at a first input end to the other end of the first vortex ring fiber 40621, at a second input end to the other end of the second single-mode fiber 40622, and at an output end to one end of a second vortex ring fiber 40624. The first tapered coupler 40623 receives the second sub-signal light and the first sub-vortex light, converts the second sub-signal light into second sub-vortex light, and the vortex mode OAM 11OAM 01 Mode and OAM 11 Mode multiplexed transmission in the second vortex ring fiber.

[0083] A third vortex ring fiber 40625 is connected to the other end of the second vortex ring fiber 40624.

[0084] A third single-mode fiber 40626 is connected to the output end of the fiber extension line 405.

[0085] A second tapered coupler 40627 is connected to the other end of the third vortex ring fiber 40625 at the first input end, to the other end of the third single-mode fiber 40626 at the second input end, and to a fourth vortex ring fiber 40628 at the output end. The third vortex ring fiber 40625 is welded to the second vortex ring fiber at the welding point 500, realizing the cascade of two fiber mode couplers.

[0086] In this process, after the single-mode fiber is pre-tapered and matched, the coupling region between the single-mode fiber and the vortex ring fiber is tapered and fused, realizing selective coupling of vortex modes. Two fiber mode couplers are cascaded to realize three vortex mode multiplexing. A single-mode fiber is welded to the ring fiber at the input end at the welding point 400, and the Gaussian mode is transmitted to the vortex ring fiber through the single-mode fiber, exciting the vortex mode OAM 01 in the vortex ring fiber. The Gaussian mode input by the other end single-mode fiber is transmitted to the tapered coupling region 1, coupling to generate the vortex mode OAM 11 in the ring fiber. 01 Mode and OAM 11 Mode multiplexed transmission in the vortex ring fiber; the ring fiber at the output end of the first fiber mode coupler is welded to the ring fiber at the input end of the second fiber mode coupler at the welding point 500, realizing the cascade of two fiber mode couplers. The Gaussian mode input by the single-mode fiber of the second fiber mode coupler is transmitted to the tapered coupling region 2, coupling to excite the vortex mode OAM 21 in the ring fiber. 21 Mode and the OAM 01 , OAM 11 Mode in the vortex ring fiber are multiplexed and transmitted together, realizing three vortex mode multiplexing.

[0087] The first vortex transmitting light is demultiplexed after being received by the opposite end optical module, the vortex mode light is converted into Gaussian mode, the first pilot vortex light is converted into first pilot light which is used as the local oscillator light for coherent detection, the signal light and the pilot light are coherently detected by using different vortex mode channels, the pilot light at the receiving end is used as the local oscillator light to realize self-homodyne coherent transmission, the influence of frequency offset and phase noise is eliminated, a complex carrier recovery algorithm is not needed, the complexity, power consumption and cost of the coherent communication system are reduced, and the limitations of high power consumption, high complexity and high cost of the traditional coherent detection are broken through.

[0088] The optical transmitting assembly provided by the embodiment of the application comprises a first laser, and a first coupler arranged at a light transmitting end of the first laser. The first coupler divides the light emitted by the first laser into three beams. A first modulator modulates the light at a first output end of the first coupler, a second modulator modulates the light at a second output end of the first coupler, and a vortex mode multiplexing module is connected with the first modulator, the second modulator and a third output port of the first coupler respectively, and converts the signal light into vortex mode and multiplexes the signal light into one beam. In the application, the first modulator and the second modulator load data on the signal light, the light at the third output port of the first coupler is used as pilot light, the transmitting light is converted into vortex light with different angular momenta by the vortex mode multiplexing module, the signal light and the pilot light are transmitted by using different vortex mode channels, the pilot light at the receiving end is used as the local oscillator light to realize self-homodyne coherent transmission, the influence of frequency offset and phase noise is eliminated, a complex carrier recovery algorithm is not needed, the complexity, power consumption and cost of the coherent detection system are reduced, and the limitations of high power consumption, high complexity and high cost of the traditional coherent detection are broken through.

[0089] Similarly, after receiving the vortex receiving light of the opposite end optical module, the vortex receiving light is demultiplexed, the vortex mode light is converted into Gaussian mode, and the second pilot vortex light is converted into receiving pilot light which is used as the local oscillator light for coherent detection and coherently detected with the demultiplexed signal light.

[0090] Figure 10 A structure schematic diagram of an optical receiving assembly shown by the embodiment of the application is shown in FIG. 3, Figure 11 A signal schematic diagram of an optical receiving assembly shown by the embodiment of the application is shown in FIG. 4, Figure 10 and Figure 11As shown in the figure, to realize the demultiplexing of the vortex light signal transmitted by the opposite end optical module, the optical receiving assembly provided by the embodiment of the application comprises a vortex mode demultiplexing module 501, an input end of which is connected with a receiving optical fiber 507 to receive vortex receiving light. The vortex mode demultiplexing module 501 receives the vortex light transmitted by the opposite end optical module, for the convenience of description, referred to as vortex receiving light, demultiplexes the vortex receiving light, and demultiplexes the vortex receiving light into a first sub-receiving signal light of Gaussian mode, a second sub-receiving signal light and a receiving pilot light. The vortex mode demultiplexing module 501 is provided with a plurality of output ports, a first output port outputs the first sub-receiving signal light and is connected with a first coherent receiver; a second output port outputs the receiving pilot light and is connected with a second coupler; and a third output port outputs the second sub-receiving signal light and is connected with a second coherent receiver.

[0091] In the embodiment of the application, the vortex receiving light transmitted in the receiving optical fiber is a mixed light of a signal light with different vortex modes and a pilot light.

[0092] The second coupler 502 is connected with the second output port of the vortex mode demultiplexing module 501, and is used for coupling the receiving pilot light into a first sub-pilot light and a second sub-pilot light.

[0093] The first coherent receiver is connected with the first output port of the vortex mode demultiplexing module 501 and the output end of the second coupler 502, receives the first sub-receiving signal light and the first sub-pilot light, and mixes and balances the detection of the first sub-receiving signal light and the first sub-pilot light. The first coherent receiver comprises a third mixer 503, which receives the first sub-receiving signal light and the first sub-pilot light, and couples the first sub-receiving signal light and the first sub-pilot light to form a first receiving mixed light. The output end of the third mixer 503 is connected with a first detector 504. The first detector 504 receives the first mixed signal light, converts the first receiving mixed light into a first electric signal, and transmits the first electric signal to a digital processor 310. The digital processor 310 recovers and demodulates the signal after sampling the first electric signal through digital signal processing, realizes self-homodyne coherent detection based on vortex mode multiplexing, and the first detector is a balanced detector.

[0094] The second coherent receiver receives the second sub-received signal light and the second sub-pilot light, and mixes and balanced detects the second sub-received signal light and the second sub-pilot light. The second coherent receiver comprises: a fourth mixer 505 receiving the second sub-received signal light and the second sub-pilot light, and mixing the second sub-received signal light and the second sub-pilot light to form second received mixed light. The output end of the fourth mixer 505 is connected with a second detector 506. The second detector 506 receives the first received mixed light, balanced detects the first received mixed light to convert the first received mixed light into a second electrical signal, and transmits the second electrical signal to the digital processor 310. The digital processor 310 recovers and demodulates the signal through digital signal processing after sampling the second electrical signal, realizes self-homodyne coherent detection based on vortex mode multiplexing, and the second detector 506 is a balanced detector.

[0095] In some embodiments of the present application, the receiving optical fiber 507 is also connected with an external optical fiber, which is used to transmit the first received signal light emitted by the opposite end optical module, that is, the vortex received light emitted by the opposite end optical module.

[0096] According to the reversibility of light, the vortex mode demultiplexing module and the vortex mode multiplexing module have the same structure, that is, the demultiplexing of a plurality of vortex signal lights can be realized.

[0097] Figure 11 The solid arrow represents the Gaussian light transmission path, and the dashed arrow represents the vortex mode light transmission path.

[0098] Figure 12 A vortex mode demultiplexing module structure diagram shown in an embodiment of the present application is shown in FIG. 5. Figure 12 As shown in FIG. 5, the vortex mode demultiplexing module 501 is a free-space optical device vortex mode multiplexing module, which comprises a converging lens, a polarizer, a spatial light modulator, a beam splitter and a converging lens. The beam splitter is used to split the light of different vortex modes, the split vortex light is adjusted to Gaussian mode by the spatial light modulator, and then the polarized light is adjusted to non-polarized light by the polarization of the polarizer, and then converges to the outlet end through the converging lens.

[0099] Specifically, the first collimating lens 5011 is arranged at the outlet of the receiving optical fiber 507 to collimate the vortex received light.

[0100] The first beam splitter 5012 is arranged on the light path of the first collimating lens 5011 to split the vortex received light to generate the first vortex received pilot light and the second vortex received signal light.

[0101] The fourth spatial light modulator 5013 is arranged on the first light output path of the first beam splitter 5012, and is used for converting the first vortex received pilot light from a vortex mode into a Gaussian mode, which is referred to as received pilot light below. The fourth polarizer 5014 is arranged between the fourth spatial light modulator 5013 and the second converging lens 5015, and is used for adjusting the polarization direction of the received pilot light and eliminating the polarization state. The second converging lens 5015 is used for focusing the received pilot light and transmitting the received pilot light to the second coupler 502. The second converging lens 5015 is located at the second output port of the vortex mode demultiplexing module 501.

[0102] The second coupler 502 divides the received pilot light into a first sub-pilot light and a second sub-pilot light.

[0103] The second beam splitter 5016 is arranged on the second light output path of the first beam splitter 5012, and is used for dividing the second vortex received signal light into two beams, which are a third sub-signal light and a fourth sub-signal light. At this time, the first sub-received signal light and the second sub-received signal light are in vortex modes and are different vortex modes.

[0104] The fifth spatial light modulator 5017 is arranged on the first light output path of the second beam splitter 5016, and is used for converting the third sub-signal light from a vortex mode into a Gaussian mode. The fifth polarizer 5018 is arranged between the fifth spatial light modulator 5017 and the third converging lens 5019, and is used for adjusting the polarization direction of the first sub-received signal light and eliminating the polarization state. The third converging lens 5019 is used for focusing the received pilot light and transmitting the received pilot light to the third frequency mixer 503. The third converging lens 5019 is located at the first output port of the vortex mode demultiplexing module 501.

[0105] The sixth spatial light modulator 50110 is arranged on the second light output path of the second beam splitter 5016, and is used for converting the fourth sub-signal light from a vortex mode into a Gaussian mode. The sixth polarizer 50111 is arranged between the sixth spatial light modulator 50110 and the fourth converging lens 50112, and is used for adjusting the polarization direction of the first sub-received signal light and eliminating the polarization state. The third converging lens 5019 is used for focusing the received pilot light and transmitting the received pilot light to the fourth frequency mixer 505. The third converging lens 5019 is located at the third output port of the vortex mode demultiplexing module 501.

[0106] The input port of the vortex mode demultiplexing module 501 receives vortex received light, which is a mixed mode of a signal light and a pilot light having different vortex modes. The output light of the vortex mode demultiplexing module 501 is in a Gaussian mode, wherein the first output port outputs a first sub-received signal light in a Gaussian mode, the second output port outputs a received pilot light in a Gaussian mode, and the third output port outputs a second sub-received signal light in a Gaussian mode.

[0107] In some embodiments of the present application, the second coupler 502 specifically receives pilot light as several paths, which can be set according to actual needs, and can be 3 paths as shown in the present application, or 4 paths, 5 paths or other paths. In the present application, the second coupler 502 specifically receives first sub-pilot light and second sub-pilot light.

[0108] The spatial light modulator provided by the embodiments of the present application is a reflective spatial light modulator, and the included angle between the input light path and the output light path is as small as possible.

[0109] In some embodiments of the present application, the vortex mode used for transmitting and receiving pilot light can be a 0-order vortex mode, a 1-order vortex mode, or other order vortex modes.

[0110] Figure 13 Another vortex mode demultiplexing module structure diagram provided by the embodiments of the present application is shown in FIG. 6. Figure 13 The present application also provides another vortex mode multiplexing module, as shown in FIG. 7.

[0111] The third tapered coupler 50122 is connected with the first receiving vortex ring fiber 50120 at the first input end and connected with the first receiving single-mode fiber 50121 at the second input end. The first receiving vortex ring fiber 50120 contains a mixed light of pilot light and received signal light with different vortex modes. As shown in the figure, the first receiving vortex ring fiber 50120 contains first sub-received signal light with vortex mode OAM1, received pilot light with vortex mode OAM2, and second sub-received signal light with vortex mode OAM3. The first output end of the third tapered coupler 50122 is connected with the second receiving single-mode fiber 50123, which is the first output port of the vortex mode multiplexing module. The second receiving single-mode fiber 50123 outputs first sub-received signal light with Gaussian mode. The second output end of the third tapered coupler 50122 is connected with the second receiving vortex ring fiber 50124, which contains received pilot light with vortex mode OAM2 and second sub-received signal light with vortex mode OAM3.

[0112] The fourth taper coupler 50125 is connected with the third receiving vortex annular optical fiber 50126 at the first input end and the third receiving single-mode optical fiber 50129 at the second input end. The third receiving vortex annular optical fiber 50126 is connected with the second receiving vortex annular optical fiber 50124 at the welding spot 600, and the third receiving vortex annular optical fiber 50126 contains the received pilot light of the vortex mode OAM2 and the second sub-received signal light of the vortex mode OAM3. The third receiving single-mode optical fiber 50129 does not contain light input. The first output end of the fourth taper coupler 50125 is connected with the fourth receiving single-mode optical fiber 50127, which is the second output port of the vortex mode multiplexing module. The fourth receiving single-mode optical fiber 50127 outputs the received pilot light of the Gaussian mode. The second output end of the fourth taper coupler 50125 is connected with the fourth receiving vortex annular optical fiber 50128, and the fourth receiving vortex annular optical fiber 50128 contains the second sub-received signal light of the vortex mode OAM3.

[0113] The fourth receiving single-mode optical fiber 50127 is connected with the fifth receiving single-mode optical fiber 50130, and the second sub-received signal light is converted from the vortex mode to the Gaussian mode. The fourth receiving vortex annular optical fiber 50128 is connected with the third output port of the vortex mode multiplexing module.

[0114] In the present application, the vortex receiving light emitted by the opposite end optical module is received, the vortex receiving light is demultiplexed, and the vortex mode light is converted into the Gaussian mode. The second pilot vortex light is converted into the received pilot light and used as the local oscillator light for coherent detection. The signal light after demultiplexing is coherently detected. The signal light and the pilot light are transmitted by different vortex mode channels. The received pilot light is used as the local oscillator light to realize self-homodyne coherent transmission, which eliminates the influence of frequency offset and phase noise. The complex carrier recovery algorithm is not needed, the complexity, power consumption and cost of the coherent communication system are reduced, and the limitations of high power consumption, high complexity and high cost of the traditional coherent detection are broken through.

[0115] The light emitting assembly provided in the embodiment of the present application comprises: a first laser, and a first coupler arranged at a light emitting end of the first laser. The first coupler divides the light emitted by the first laser into three beams. A first modulator modulates the light at a first output end of the first coupler, a second modulator modulates the light at a second output end of the first coupler, and a vortex mode multiplexing module is connected with the first modulator, the second modulator and a third output port of the first coupler, and converts the signal light into vortex modes and multiplexes into one beam. In the present application, the first modulator and the second modulator load data to the signal light, and the light at the third output port of the first coupler is used as pilot light. The vortex mode multiplexing module converts the emitted light into vortex light with different angular momenta, realizes the transmission of the signal light and the pilot light through different vortex mode channels, and the receiving end receives the pilot light as a local oscillator light to realize self-homodyne coherent transmission, eliminates the influence of frequency offset and phase noise, does not need a complex carrier recovery algorithm, reduces the complexity, power consumption and cost of the coherent detection system, and breaks through the limitations of high power consumption, high complexity and high cost of the traditional coherent detection.

[0116] Similarly, after receiving the vortex receiving light of the optical module at the opposite end, the vortex receiving light is demultiplexed, and the vortex mode light is converted into Gaussian mode, wherein the second pilot vortex light is converted into receiving pilot light and used as a local oscillator light for coherent detection with the demultiplexed signal light.

[0117] The light receiving assembly provided in the present application can demultiplex the received vortex light into Gaussian mode first sub-receiving signal light, second sub-receiving signal light and receiving pilot light through a vortex mode demultiplexing module, divide the receiving pilot light through a coupler, and divide the receiving pilot light as a local oscillator light for coherent detection with third sub-signal light and fourth sub-signal light, realize self-homodyne coherent detection of multiple groups of data signals transmitted by the opposite end at the same time, eliminate the influence of frequency offset and phase noise, do not need a complex carrier recovery algorithm, reduce the complexity, power consumption and cost of the coherent detection system, and break through the limitations of high power consumption, high complexity and high cost of the traditional coherent detection.

[0118] Figure 14 A self-homodyne coherent detection system structure schematic diagram is provided in the embodiment of the present application. As shown in Figure 14As shown, the embodiment of the present application also provides a self-zero difference coherent detection system, comprising: a transmitting light module and a receiving light module. The transmitting light module comprises a light transmitting component for transmitting mixed frequency vortex signal light, and the receiving light module is used for receiving the mixed frequency vortex signal light of the transmitting light module. The pilot light and the signal light are obtained by demultiplexing the mixed frequency vortex signal light. The received pilot light is used as the local oscillator light to realize self-zero difference coherent transmission, which eliminates the influence of frequency offset and phase noise, and does not need a complex carrier recovery algorithm, thereby reducing the complexity, power consumption and cost of the coherent detection system, and breaking through the limitations of high power consumption, high complexity and high cost of traditional coherent detection. The light transmitting component comprises: a first laser 401, a first coupler 402 arranged at the light transmitting end of the first laser 401. The first coupler 402 is provided with a plurality of output ports, including a first output port, a second output port and a third output port. A first modulator 403 is connected with the first output port of the first coupler 402, and a second modulator 404 is connected with the second output port of the first coupler 402. A vortex mode multiplexing module 406 is connected with the first modulator 403, the second modulator 404 and the third output port of the first coupler 402 respectively, and converts the signal light into a vortex mode and multiplexes it into a bundle. In the present application, the first modulator and the second modulator load data on the signal light, and the light output by the third output port is used as the local oscillator light. The transmitting light is converted into vortex light with different angular momenta by the vortex mode multiplexing module 406, and the signal light and the pilot light are transmitted by different vortex mode channels.

[0119] The light receiving assembly comprises: a vortex mode demultiplexing module, an input end of which is connected with the vortex mode multiplexing module 406 through a vortex ring optical fiber, receives first vortex emitted light, and demultiplexes the first vortex emitted light into third sub-signal light, fourth sub-signal light and received pilot light in Gaussian modes. A second coupler 502 is used to couple the received pilot light into first sub-pilot light and second sub-pilot light. A third mixer 503 receives the third sub-signal light and the first sub-pilot light, mixes the third sub-signal light and the first sub-pilot light to form first mixed signal light. The output end of the third mixer 503 is connected with a first detector 504. The first detector 504 receives the first mixed signal light, converts the first mixed signal light into first electric signal through balanced detection, and transmits the first electric signal to the digital processor 310. The digital processor 310 recovers and demodulates the signal through digital signal processing after sampling the first electric signal, and realizes self-homodyne coherent detection based on vortex mode multiplexing. A fourth mixer 505 receives the fourth sub-signal light and the second sub-pilot light, and couples the third sub-signal light and the second sub-pilot light to form second mixed signal light. The output end of the fourth mixer 505 is connected with a second detector 506. The second detector 506 receives the second mixed signal light, converts the second mixed signal light into second electric signal through balanced detection, and transmits the second electric signal to the digital processor 310. The digital processor 310 recovers and demodulates the signal through digital signal processing after sampling the second electric signal, and realizes self-homodyne coherent detection based on vortex mode multiplexing.

[0120] The first laser outputs Gaussian light, which is split into signal light and pilot light. The signal light is divided into N paths after being loaded with a signal by a modulator, and is converted into N+1 vortex modes with the pilot light through a vortex mode multiplexing module and is multiplexed and transmitted in a vortex ring optical fiber. The vortex mode demultiplexing module converts the multiplexed vortex mode into N paths of signal Gaussian light and one path of pilot Gaussian light. The pilot light is divided into N paths and used as a local oscillator light. The N paths of signal light are coherently detected by N coherent receivers to realize self-homodyne coherent detection based on vortex mode multiplexing. The present application breaks through the limitations of high complexity, high power consumption and high cost of traditional coherent detection, has a wide application prospect in the field of vortex mode space division multiplexing and short-distance optical interconnection systems, and fills the gap in the related technical field.

[0121] Figure 15 A pilot light path and signal light path length alignment module based on vortex mode multiplexing self-homodyne coherent detection provided in the present application is shown in a schematic diagram. Figure 15As shown, the pilot light path and signal light path length alignment module in self-homodyne coherent detection based on vortex mode multiplexing includes: a first laser 401, a first coupler 402, a first modulator 403, an arbitrary waveform generator 4031, a fiber extension line 405, a second sub-coupler 19, a vortex mode multiplexing module 406, a vortex ring fiber 508, a vortex mode demultiplexing module 501, a third coupler 23, a coherent receiver 11, a second laser 13, a fourth coupler 14, a fifth coupler 15, a sixth coupler 16, a third photodetector 17, and a fourth photodetector 18. The first laser 401 outputs Gaussian light to the first modulator 403, and the arbitrary waveform generator 4031 outputs a 10Gbaud QPSK signal to the Gaussian light via the first modulator 403. The first coupler 402 divides the QPSK signal light into two paths, one of which is a signal light transmission path including a second I / Q modulator 3, a second sub-coupler 19, a vortex mode multiplexing module 406, a vortex ring fiber 508, and a vortex mode demultiplexing module 501, and the other of which is a pilot light transmission path including a fiber extension line 405, a vortex mode multiplexing module 406, a vortex ring fiber 508, a vortex mode demultiplexing module 501, and a third coupler 23. The vortex ring fiber 8 has N+1 vortex mode multiplexing transmissions. At the receiving end, the second laser 13 outputs Gaussian light as the local oscillator light of the path alignment module, and the local oscillator light is divided into 2N paths via the fourth coupler 14. The 2N paths of local oscillator light and the 2N paths of QPSK signal light are mixed via 2N couplers, and the mixed light is converted into 2N paths of electrical signals via 2N photodetectors. Each path of electrical signal is sampled, and then digital signal processing is performed. The Minn algorithm is used to calculate the number of symbols between the start bits of a frame of 2N paths of QPSK symbols, and the signal light and pilot light path mismatch length is calculated according to the symbol rate and the transmission rate of light in the fiber. The optical extension line is adjusted to equalize the signal light and pilot light path lengths.

[0122] Since the above embodiments are described in combination with other modes, the same parts are present between different embodiments, and the same and similar parts between the embodiments in the description are referred to each other. Details are not described here.

[0123] It should be noted that, in the specification, relational terms such as "first" and "second", and the like, can be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a circuit, item, or process that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such circuit, item, or process. Without further limitation, an element preceded by "comprises a" does not, without more constraints, foreclose the existence of additional identical elements in the structure, item, or process that includes the recited element.

[0124] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the content of the following claims.

[0125] The above-described embodiments of the application do not constitute a limitation.

Claims

1. An optical module characterized by comprising: include: The receiving optical fiber receives vortex receiving light, which is a mixed vortex light with a first sub-receiving signal light and a receiving pilot light, wherein the first sub-receiving signal light and the receiving pilot light have different vortex modes. A vortex mode demultiplexing module, whose input end is connected to the receiving optical fiber, is used to split the first sub-received signal light and the receiving pilot light and convert them into Gaussian mode. A first coherent receiver has its first input port connected to the first output port of the vortex mode demultiplexing module, and its second input port connected to the second output port of the vortex mode demultiplexing module. It is used to mix and detect the first sub-received signal light and the received pilot light and convert them into a first electrical signal.

2. The optical module according to claim 1, characterized by The vortex mode demultiplexing module includes: The first beam splitter is used to split the hybrid vortex light into beams and output the first sub-received signal light and the received pilot light in vortex mode. A fourth spatial light modulator is disposed on the first output optical path of the first beam splitter, and is used to convert the received pilot light from vortex mode to Gaussian mode. The fifth spatial light modulator is disposed on the second output optical path of the first beam splitter and is used to convert the first sub-received signal light from vortex mode to Gaussian mode.

3. The optical module according to claim 2, characterized by The vortex mode demultiplexing module further includes: a fourth polarizer, disposed on the output optical path of the fourth spatial light modulator, for eliminating the polarization state of the received pilot light; The fifth polarizer is disposed on the output optical path of the fifth spatial light modulator to eliminate the polarization state of the first received signal light.

4. The optical module according to claim 1, characterized by The first coherent receiver includes: a first mixer connected to the vortex mode demultiplexing module, used to mix the first sub-received signal light and the received pilot light to form a first received mixed light; A first balanced detector, connected to the first mixer, converts the first received mixed light into a first electrical signal.

5. The optical module of claim 2, wherein, The fourth and fifth spatial light modulators are reflective spatial light modulators.

6. The optical module of claim 1, wherein Also includes: The receiving optical fiber is a vortex ring optical fiber.

7. The optical module according to claim 6, characterized by vortex ring fiber includes: The central region is located at the center of the vortex ring optical fiber; A ring-shaped fiber core covers the outer side of the central region; A cladding layer, covering the outer side of the annular fiber core; The central region has the same refractive index as the cladding; The refractive index of the annular fiber core is greater than that of the cladding.

8. The optical module of claim 1, wherein, The vortex mode demultiplexing module includes: The third tapered coupler has its vortex input end connected to the receiving optical fiber, its single-mode output end connected to the second receiving single-mode optical fiber, and its vortex output end connected to the second receiving vortex loop optical fiber. The first sub-received signal light output from the second receiving single-mode fiber is in Gaussian mode; The second receiving vortex ring fiber outputs vortex-mode receiving pilot light. The third receiving single-mode fiber is connected to the second receiving vortex loop fiber to convert the received pilot light from vortex mode to Gaussian mode.

9. An optical module characterized by comprising: include: a receiving optical fiber, configured to receive vortex receiving light, the vortex receiving light being a mixed vortex light of a first sub-receiving signal light, a second sub-receiving signal light and a receiving pilot light, the first sub-receiving signal light, the second sub-receiving signal light and the receiving pilot light having different vortex modes; a vortex mode demultiplexing module, connected with the receiving optical fiber, configured to split the first sub-receiving signal light, the second sub-receiving signal light and the receiving pilot light and convert them into Gaussian modes; a second coupler, disposed at a second output port of the vortex mode demultiplexing module, configured to receive the receiving pilot light in Gaussian mode and split the pilot light into a first sub-pilot light and a second sub-pilot light; a first coherent receiver, having a first input port connected with a first output port of the vortex mode demultiplexing module and a second input port connected with a first output port of the second coupler, configured to mix and detect the first sub-receiving signal light and the first sub-pilot light into a first electrical signal; a second coherent receiver, having a first input port connected with a third output port of the vortex mode demultiplexing module and a second input port connected with a second output port of the second coupler, configured to mix and detect the second sub-receiving signal light and the second sub-pilot light into a second electrical signal.

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