Space laser communication system with self-testing function and working method thereof

Abstract

The invention relates to a laser communication system and method, in particular to a space laser communication system with a self-testing function and a working method of the space laser communication system, and aims to overcome the defect that in the prior art, after a laser communication terminal goes wrong in on-orbit operation, on-orbit detection is difficult. The space laser communication system with the self-test function comprises a transmitting unit, a receiving unit and an optical antenna unit, wherein the transmitting unit comprises a laser transmitting module, a modulator and a wavelength division multiplexer; the receiving unit comprises an optical amplifier, an optical filter and a demodulation detection module which are connected in sequence; one output end of the wavelength division multiplexer is connected with the input end of the optical antenna unit, and the other output end of the wavelength division multiplexer is connected with one input end of the optical amplifier to form a self-measuring light path. In the self-test mode, self-test can be achieved through the self-test light path, and then the performance of the self-test light path is directly verified.

Description

Technical Field

[0001] The invention relates to a laser communication system and method, and in particular to a space laser communication system with a self-test function and a working method thereof. Background Art

[0002] With the rapid development of space information network, its network system is becoming more and more complex. The amount of data required to be transmitted and processed by various aircraft of space-based platforms and near-space platforms is increasing. Among them, the data rate of hyperspectral imager can reach 100Gbps, the data rate of hyperspectral camera can reach more than 50Gbps, and the data rate of synthetic aperture radar can reach 60Gbps or even higher. These data rates require the information transmission system in the space information network to have stronger transmission capabilities. However, the bandwidth bottleneck of existing microwave communication technology is difficult to meet the demand for ultra-high-speed information transmission, which is a huge challenge facing the development of space information network.

[0003] Compared with traditional microwave communication, space laser communication has a very high data transmission bandwidth, which can reach the Tbps level, which makes its data transmission capacity far exceed that of microwave communication; at the same time, space laser communication is almost unaffected by traditional electromagnetic interference means, and can maintain good communication quality in different electromagnetic environments; its narrow beam width and high linearity make it more difficult to be eavesdropped or interfered, improving the concealment of communication; due to the small divergence angle of the laser, the antenna of the space laser communication terminal is smaller and consumes less power. These advantages show that space laser communication can better meet the needs of the rapid development of future space information networks compared with microwave communication.

[0004] At present, space laser communications are developing rapidly at home and abroad, and space laser communication terminals have been used in large numbers in orbit. However, the space environment is complex, and space laser communication terminals are susceptible to radiation, extreme temperatures, space debris and micrometeorites, etc. At the same time, their mechanical components, lasers and optical devices will age with time. These problems make space laser communication terminals less reliable and have a high failure rate. When problems arise in the on-orbit operation of space laser communication terminals, on-orbit detection becomes a problem due to their special application scenarios. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcoming in the prior art that after a problem occurs in the on-orbit operation of a laser communication terminal, it is difficult to detect it on-orbit, and to provide a space laser communication system with a self-test function and a working method thereof.

[0006] To achieve the above objectives, the technical solutions provided by the present invention are as follows:

[0007] A space laser communication system with a self-test function comprises a transmitting unit, a receiving unit and an optical antenna unit, wherein the transmitting unit comprises a laser transmitting module, a modulator and a wavelength division multiplexer; the receiving unit comprises an optical amplifier, an optical filter and a demodulation detection module connected in sequence; the laser transmitting module is used to transmit a laser with a wavelength of λ1 or λ2; the first input end of the modulator is connected to the output end of the laser transmitting module, and the second input end thereof is connected to a local baseband electrical signal which has been encoded and amplified, so as to load the local baseband electrical signal onto a corresponding laser through electro-optical modulation, and output a modulated optical signal with a wavelength of λ1 or λ2; the input end of the wavelength division multiplexer is connected to the output end of the modulator, one output end thereof is connected to the input end of the optical antenna unit, and the other output end is connected to the optical baseband electrical signal. One input end of the optical amplifier is connected to transmit a modulated optical signal with a wavelength of λ1 to the optical antenna unit, and transmits a laser with a wavelength of λ2 to the optical amplifier, so as to form a self-test optical path; the spatial transceiver end of the optical antenna unit corresponds to the external laser communication terminal, and is used to output a modulated optical signal with a wavelength of λ1 to the external laser communication terminal and receive an input optical signal with a wavelength of λ2 emitted by the external laser communication terminal; the other input end of the optical amplifier is connected to the output end of the optical antenna unit, and is used to amplify the optical signal output by the wavelength division multiplexer or the optical antenna unit; the optical filter is used to perform narrow-band filtering on the amplified optical signal to remove background noise; the receiving wavelength of the demodulation detection module is λ2, and is used to demodulate the optical signal after filtering out the background noise and convert it into an electrical signal to output to an external receiving device.

[0008] Furthermore, the receiving unit also includes an adjustable optical attenuator;

[0009] The input end of the adjustable optical attenuator is connected to another output end of the wavelength division multiplexer, and is used to attenuate the modulated optical signal with a wavelength of λ2;

[0010] An input end of the optical amplifier is connected to an output end of the adjustable optical attenuator.

[0011] Furthermore, a high-power optical amplifier is provided between an output end of the wavelength division multiplexer and an input end of the optical antenna unit, and the high-power optical amplifier is used to amplify the modulated optical signal with a wavelength of λ1.

[0012] Furthermore, the laser emission module is a wavelength-tunable laser, which is used to emit laser light with a wavelength of λ1 or λ2.

[0013] Furthermore, the laser emission module includes a first laser and a second laser, which are used to emit lasers with wavelengths of λ1 and λ2 respectively.

[0014] Furthermore, it also includes a first optical coupler and a data processing module;

[0015] The two input ends of the first optical coupler are respectively connected to the output ends of the first laser and the second laser, and the output end thereof is connected to the first input end of the modulator;

[0016] The input end of the data processing module is used to receive a local baseband electrical signal, and the output end is connected to the second input end of the modulator, and is used to encode and amplify the local baseband electrical signal and then transmit it to the modulator.

[0017] Further, it also includes a second optical coupler and a bias controller;

[0018] The input end of the second optical coupler is connected to the output end of the modulator, one output end of the second optical coupler is connected to the input end of the wavelength division multiplexer, and the other output end of the second optical coupler is connected to the bias controller;

[0019] The output end of the bias controller is connected to the third input end of the modulator, and is used to feed back an input bias voltage value to the modulator, thereby controlling the working state of the modulator and realizing intensity modulation or phase modulation.

[0020] Furthermore, the receiving unit further includes a third optical coupler;

[0021] The output end of the optical antenna unit and the output end of the adjustable optical attenuator are connected to the optical amplifier through a third optical coupler;

[0022] The optical amplifier is a low-noise optical amplifier.

[0023] At the same time, the present invention also provides a working method of the above-mentioned space laser communication system with a self-test function, which is special in that it includes a communication mode and a self-test mode;

[0024] The communication mode comprises the following steps:

[0025] Step 1, the laser emission module emits a laser with a wavelength of λ1, and at the same time inputs a local baseband electrical signal into a modulator, and loads the encoded and amplified local baseband electrical signal onto the laser through electro-optical modulation to obtain a modulated optical signal with a wavelength of λ1; the wavelength division multiplexer transmits the modulated optical signal with a wavelength of λ1 into space through an optical antenna unit;

[0026] Step 2, the optical antenna unit receives an input optical signal with a wavelength of λ2 emitted by an external laser communication terminal, amplifies it through an optical amplifier and an optical filter, filters out noise, and then transmits it to a demodulation detection module;

[0027] Step 3, the demodulation detection module demodulates the input optical signal with a wavelength of λ2, recovers the baseband electrical signal corresponding to the external laser communication terminal, and completes the data reception of the external laser communication terminal;

[0028] The self-test mode includes the following steps:

[0029] Step 1, the laser transmitting module transmits a laser with a wavelength of λ2, and at the same time inputs a local baseband electrical signal into a modulator, and loads the encoded and amplified local baseband electrical signal onto the laser through electro-optical modulation to obtain a modulated optical signal with a wavelength of λ2; the wavelength division multiplexer transmits the modulated optical signal with a wavelength of λ2 to a receiving unit;

[0030] Step 2, the optical amplifier and the optical filter of the receiving unit sequentially amplify the modulated optical signal with a wavelength of λ2 and filter out the noise, and then transmit it to the demodulation detection module;

[0031] Step 3, the demodulation detection module demodulates the modulated optical signal with a wavelength of λ2 and recovers the local baseband electrical signal;

[0032] Step 4: Perform a bit error rate test on the obtained local baseband electrical signal to verify the performance of the self-test optical path and complete the self-test.

[0033] Beneficial effects of the present invention:

[0034] 1. In the space laser communication system with a self-test function of the present invention, the other output end of the wavelength division multiplexer is connected to the optical amplifier, so that the transmitting unit and the receiving unit are directly connected to form a closed-loop self-test optical path, thereby realizing the self-test of the space laser communication system and solving the problem of difficulty in locating faults when the space laser communication system is running in orbit.

[0035] 2. The space laser communication system with self-test function of the present invention has a simple structure and high reliability, can support various communication systems such as OOK, BPSK, DPSK, etc., is flexible to use, and can be applied to various scenarios such as airborne laser communication, satellite laser communication, and ground laser communication.

[0036] 3. The working method of the space laser communication system with self-test function of the present invention includes two modes. In the self-test mode, the wavelength division multiplexer directly transmits the modulated optical signal with a wavelength of λ2 to the receiving unit, which is received and demodulated by the demodulation detection module to obtain a local baseband electrical signal. By performing a bit error rate test on it, the performance of the self-test optical path is verified, thereby realizing the on-orbit self-test of the space laser communication system and facilitating the detection during on-orbit operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of an embodiment of a space laser communication system with a self-test function of the present invention;

[0038] Description of reference numerals:

[0039] 1-transmitting unit, 101-first laser, 102-second laser, 103-modulator, 104-wavelength division multiplexer, 105-high power optical amplifier, 106-bias controller, 107-data processing module, 108-first optical coupler, 109-second optical coupler;

[0040] 2-receiving unit, 201-optical amplifier, 202-optical filter, 203-demodulation detection module, 204-adjustable optical attenuator, 205-third optical coupler;

[0041] 3- Optical antenna unit. DETAILED DESCRIPTION

[0042] When a space laser communication terminal is running in orbit as a satellite payload, it is impossible to manually test the performance of the optical communication device of the space laser communication terminal. Once a link interruption occurs, effective positioning cannot be achieved. Therefore, the present invention provides a space laser communication system with a self-test function and a working method thereof. A self-test optical path is set in the space laser communication system to realize self-test.

[0043] The space laser communication system with a self-test function of the present invention comprises a transmitting unit 1, a receiving unit 2 and an optical antenna unit 3, wherein the transmitting unit 1 comprises a laser transmitting module, a modulator 103 and a wavelength division multiplexer 104; the receiving unit 2 comprises an optical amplifier 201, an optical filter 202 and a demodulation detection module 203 connected in sequence.

[0044] The laser emission module includes a first laser 101 and a second laser 102, which are used to emit lasers with wavelengths of λ1 and λ2, respectively. The output ends of the first laser 101 and the second laser 102 are connected to the first input end of the modulator 103 through a first optical coupler 108. In the present invention, the laser with a wavelength of λ1 is used to communicate with an external space laser communication terminal, and the laser with a wavelength of λ2 is used for local self-test. The first laser 101 and the second laser 102 are used in a time-sharing manner. In other embodiments of the present invention, the laser emission module can also be a wavelength-tunable laser, which emits lasers with a wavelength of λ1 or λ2 by setting different output light wavelengths.

[0045] The second input end of the modulator 103 is connected to the data processing module 107, and the data processing module 107 encodes and amplifies the local baseband electrical signal. The modulator 103 loads the encoded and amplified local baseband electrical signal on the laser through electro-optical modulation, and outputs a modulated optical signal with a wavelength of λ1 or λ2. A second optical coupler 109 is arranged at the output end of the modulator 103, one of the output ends of the second optical coupler 109 is connected to the input end of the wavelength division multiplexer 104, and the other output end is connected to the input end of the bias controller 106; the output end of the bias controller 106 is connected to the third input end of the modulator 103, and is used to feed back the input bias voltage value to the modulator 103, control the working state of the modulator 103, and realize intensity modulation or phase modulation.

[0046] A high-power optical amplifier 105 is provided at one output end of the wavelength division multiplexer 104, and the high-power optical amplifier 105 is used to amplify the modulated optical signal with a wavelength of λ1. The output end of the high-power optical amplifier 105 is connected to the input end of the optical antenna unit 3, and the amplified modulated optical signal with a wavelength of λ1 is transmitted to the optical antenna unit 3. The other output end of the wavelength division multiplexer 104 is connected to an input end of the optical amplifier 201 through the adjustable optical attenuator 204, so as to form a self-test optical path for transmitting the modulated optical signal with a wavelength of λ2, and transmitting it to the receiving unit 2 as a self-test optical signal.

[0047] The spatial transceiver end of the optical antenna unit 3 is set corresponding to the external laser communication terminal, and is used to output a modulated optical signal with a wavelength of λ1 to the external laser communication terminal and receive an input optical signal with a wavelength of λ2 emitted by the external laser communication terminal; the output end of the optical antenna unit 3 is connected to another input end of the optical amplifier 201. In this embodiment, the optical amplifier 201 adopts a low-noise optical amplifier for amplifying the optical signal with low noise and high gain; the optical filter 202 is used to perform narrow-band filtering on the amplified optical signal to remove background noise; the receiving wavelength of the demodulation detection module 203 is λ2, and is used to convert the optical signal into an electrical signal and output it to an external receiving device. The modulated optical signal with a wavelength of λ2 and the input optical signal with a wavelength of λ2 exist in time sharing. During self-test, the receiving unit 2 has no external input optical signal. During communication, the receiving unit 2 receives an external input optical signal but no self-test optical signal.

[0048] The receiving unit 2 further includes a third optical coupler 205 , and the output end of the optical antenna unit 3 and the output end of the adjustable optical attenuator 204 are connected to the optical amplifier 201 via the third optical coupler 205 .

[0049] The space laser communication system with a self-test function of the present invention can work in a self-test mode or a communication mode. In the self-test mode, the modulated optical signal with a wavelength of λ2 emitted by the transmitting unit 1 enters the receiving unit 2 through the self-test optical path as a self-test optical signal, and enters the optical amplifier 201 after the optical power is reduced by the adjustable optical attenuator 204, and then narrow-band filtering is performed to filter out out-of-band noise, and finally the demodulation detection module 203 converts it into an electrical signal, outputs the restored local baseband electrical signal, and tests the bit error rate, etc., and specifically includes the following steps:

[0050] S1. Control the first laser 101 to be turned off, and start the second laser 102 to generate laser light with a wavelength of λ2, which is coupled to the modulator 103 through the first optical coupler 108 .

[0051] S2. At the same time, the local baseband electrical signal is input into the data processing module 107, which encodes and amplifies the local baseband electrical signal according to the communication system, and outputs it to the modulator 103. The modulator 103 performs intensity modulation or phase modulation on the laser with a wavelength of λ2, and loads the local baseband electrical signal onto the laser with a wavelength of λ2 to obtain a modulated optical signal with a wavelength of λ2. The present invention can adopt communication systems such as OOK, BPSK, and DPSK.

[0052] S3. The modulated optical signal with a wavelength of λ2 is divided into two paths through the second optical coupler 109, one of which enters the bias controller 106. The bias controller 106 uses the feedback input modulator 103 to generate the bias voltage value V bias , control the modulator 103 to achieve intensity modulation or phase modulation.

[0053] S4. Another modulated optical signal with a wavelength of λ2 passes through the second optical coupler 109 and enters the wavelength division multiplexer 104. The wavelength division multiplexer 104 outputs the modulated optical signal with a wavelength of λ2 from its other output end according to the wavelength, and enters the adjustable optical attenuator 204 in the receiving unit 2 through the self-test optical path.

[0054] S5. The adjustable optical attenuator 204 attenuates the optical power of the modulated optical signal with a wavelength of λ2, and the attenuation value can be set according to the receiving sensitivity of the demodulation detection module 203 at different communication distances.

[0055] S6. The modulated optical signal with a wavelength of λ2 after attenuation enters the optical amplifier 201 through the third optical coupler 205 to achieve low-noise, high-gain amplification, and then is narrow-band filtered by the optical filter 202 to filter out background noise.

[0056] S7. The modulated optical signal with a wavelength of λ2 processed by the optical amplifier 201 and the optical filter 202 enters the demodulation detection module 203 to complete signal demodulation and restore the local baseband electrical signal; the demodulation detection module 203 can use direct detection or coherent detection.

[0057] S8. Perform a bit error rate test on the obtained local baseband electrical signal to verify the performance of the self-test optical path and complete the self-test.

[0058] The communication mode includes the following steps:

[0059] S1. Turn off the second laser 102 and turn on the first laser 101 to generate laser light with a wavelength of λ1, which is coupled to the modulator 103 through the first optical coupler 108 .

[0060] S2. The local baseband electrical signal is input to the data processing module 107, which encodes and amplifies the signal. The local baseband electrical signal is encoded and amplified according to the communication system and output to the modulator 103. The modulator 103 performs intensity modulation or phase modulation on the laser with a wavelength of λ1 to obtain a modulated optical signal with a wavelength of λ1.

[0061] S3. The modulated optical signal with a wavelength of λ1 is divided into two paths through the second optical coupler 109, one of which enters the bias controller 106. The bias controller 106 feeds back the bias voltage value V of the input modulator 103. bias , control the modulator 103 to achieve intensity modulation or phase modulation.

[0062] S4. The other path enters the wavelength division multiplexer 104, and the wavelength division multiplexer 104 outputs the modulated optical signal with a wavelength of λ1 from one output port thereof to the high power optical amplifier 105 according to the wavelength.

[0063] S5. The high-power optical amplifier 105 amplifies the modulated optical signal with a wavelength of λ1 and outputs it to the optical antenna unit 3, which transmits it to the external laser communication terminal for data transmission.

[0064] S6. The external laser communication terminal transmits an input optical signal with a wavelength of λ2, which is received by the optical antenna unit 3 and coupled into the optical amplifier 201 through the third optical coupler 205 to perform low-noise, high-gain amplification on the input optical signal, and then the optical filter 202 performs narrow-band filtering to remove background noise.

[0065] S7. The optical signal with a wavelength of λ2 enters the demodulation detection module 203 to complete signal demodulation, recover the baseband electrical signal corresponding to the external laser communication terminal, and complete the data reception of the external laser communication terminal.

Claims

1. A space laser communication system with a self-test function, comprising a transmitting unit (1), a receiving unit (2) and an optical antenna unit (3), characterized in that: The transmitting unit (1) comprises a laser transmitting module, a modulator (103) and a wavelength division multiplexer (104); the receiving unit (2) comprises an optical amplifier (201), an optical filter (202) and a demodulation detection module (203) which are connected in sequence; The laser emission module is used to emit laser light with a wavelength of λ1 or λ2; The first input end of the modulator (103) is connected to the output end of the laser emission module, and the second input end is connected to the encoded and amplified local baseband electrical signal, and is used to load the local baseband electrical signal onto the corresponding laser through electro-optical modulation, and output a modulated optical signal with a wavelength of λ1 or λ2; The input end of the wavelength division multiplexer (104) is connected to the output end of the modulator (103), one output end thereof is connected to the input end of the optical antenna unit (3), and the other output end is connected to an input end of the optical amplifier (201), and is used to transmit a modulated optical signal with a wavelength of λ1 to the optical antenna unit (3), and transmit a laser with a wavelength of λ2 to the optical amplifier (201), thereby forming a self-test optical path; The spatial transceiver end of the optical antenna unit (3) corresponds to an external laser communication terminal, and is used to output a modulated optical signal with a wavelength of λ1 to the external laser communication terminal and receive an input optical signal with a wavelength of λ2 emitted by the external laser communication terminal; the other input end of the optical amplifier (201) is connected to the output end of the optical antenna unit (3), and is used to amplify the optical signal output by the wavelength division multiplexer (104) or the optical antenna unit (3); the optical filter (202) is used to perform narrow-band filtering on the amplified optical signal to remove background noise; The receiving wavelength of the demodulation detection module (203) is λ2, and it is used to demodulate the optical signal after filtering out the background noise and convert it into an electrical signal to output to an external receiving device.

2. The space laser communication system with self-test function according to claim 1, characterized in that: The receiving unit (2) further comprises an adjustable optical attenuator (204); The input end of the adjustable optical attenuator (204) is connected to another output end of the wavelength division multiplexer (104) and is used to attenuate the modulated optical signal with a wavelength of λ2; An input end of the optical amplifier (201) is connected to an output end of the adjustable optical attenuator (204).

3. The space laser communication system with self-test function according to claim 2, characterized in that: A high-power optical amplifier (105) is also provided between an output end of the wavelength division multiplexer (104) and an input end of the optical antenna unit (3), and the high-power optical amplifier (105) is used to amplify a modulated optical signal with a wavelength of λ1.

4. The space laser communication system with self-test function according to claim 3, characterized in that: The laser emission module is a wavelength-adjustable laser, which is used to emit laser light with a wavelength of λ1 or λ2.

5. The space laser communication system with self-test function according to claim 3, characterized in that: The laser emission module comprises a first laser (101) and a second laser (102), which are used to emit lasers with wavelengths of λ1 and λ2 respectively.

6. The space laser communication system with self-test function according to claim 5, characterized in that: Also includes a first optical coupler (108) and a data processing module (107); The two input ends of the first optical coupler (108) are respectively connected to the output ends of the first laser (101) and the second laser (102), and the output end thereof is connected to the first input end of the modulator (103); The input end of the data processing module (107) is used to receive a local baseband electrical signal, and the output end is connected to the second input end of the modulator (103) and is used to encode and amplify the local baseband electrical signal and then transmit it to the modulator (103).

7. The space laser communication system with self-test function according to claim 6, characterized in that: Also includes a second optical coupler (109) and a bias controller (106); The input end of the second optical coupler (109) is connected to the output end of the modulator (103), one output end of the second optical coupler (109) is connected to the input end of the wavelength division multiplexer (104), and the other output end is connected to the bias controller (106); The output end of the bias controller (106) is connected to the third input end of the modulator (103) and is used to feed back an input bias voltage value to the modulator (103) to control the working state of the modulator (103) and realize intensity modulation or phase modulation.

8. The space laser communication system with self-test function according to any one of claims 2 to 7, characterized in that: The receiving unit (2) further comprises a third optical coupler (205); The output end of the optical antenna unit (3) and the output end of the adjustable optical attenuator (204) are connected to the optical amplifier (201) via a third optical coupler (205); The optical amplifier (201) is a low-noise optical amplifier.

9. A working method of a space laser communication system with a self-test function according to any one of claims 1 to 8, characterized in that: Includes communication mode and self-test mode; The communication mode comprises the following steps: Step 1, the laser emission module emits a laser with a wavelength of λ1, and at the same time inputs a local baseband electrical signal into a modulator (103), and loads the encoded and amplified local baseband electrical signal onto the laser through electro-optical modulation to obtain a modulated optical signal with a wavelength of λ1; the wavelength division multiplexer (104) transmits the modulated optical signal with a wavelength of λ1 into space through an optical antenna unit (3); Step 2, the optical antenna unit (3) receives an input optical signal with a wavelength of λ2 emitted by an external laser communication terminal, amplifies it through an optical amplifier (201) and an optical filter (202) in sequence, filters out noise, and then transmits it to a demodulation detection module (203); Step 3, the demodulation detection module (203) demodulates the input optical signal with a wavelength of λ2, recovers the baseband electrical signal corresponding to the external laser communication terminal, and completes the data reception of the external laser communication terminal; The self-test mode includes the following steps: Step 1, the laser emission module emits a laser with a wavelength of λ2, and at the same time inputs a local baseband electrical signal into a modulator (103), and loads the encoded and amplified local baseband electrical signal onto the laser through electro-optical modulation to obtain a modulated optical signal with a wavelength of λ2; the wavelength division multiplexer (104) transmits the modulated optical signal with a wavelength of λ2 to a receiving unit (2); Step 2, the optical amplifier (201) and the optical filter (202) of the receiving unit (2) sequentially amplify the modulated optical signal with a wavelength of λ2 and filter out noise, and then transmit it to the demodulation detection module (203); Step 3, the demodulation detection module (203) demodulates the modulated optical signal with a wavelength of λ2 to recover a local baseband electrical signal; Step 4: Perform a bit error rate test on the obtained local baseband electrical signal to verify the performance of the self-test optical path and complete the self-test.

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