A wireless coherent optical communication link signal equalization system

Abstract

The present invention discloses a wireless coherent optical communication link signal equalization system, which belongs to the field of wireless laser communication technology. The system comprises an optical antenna, an optical wavefront detector, an optical coupler, an optical mixer, a local oscillator laser source, an optical detector, an optical wavefront solver, an optical signal demodulator, and an optical signal demodulation controller. The present invention adopts spatial optical wavefront detection means to assist in the realization of real-time optical wavefront phase noise perception and assist in the realization of dynamic equalization of coherent optical communication links. The present invention has low complexity, high degree of automation, fast response speed, and is easy to implement.

Description

Technical Field

[0001] The present invention relates to the field of wireless laser communication technology, and in particular to a wireless coherent optical link signal equalization technology based on a digital signal processing method. Background Art

[0002] Wireless coherent optical communication passes through the atmospheric channel, and the optical signal at the receiving end is affected by the channel, which will produce spatial optical wavefront distortion, and then cause the received signal to produce complex time-varying phase noise. This will affect wireless communication, especially coherent wireless laser communication, and may lead to reduced mixing efficiency and poor communication quality, thus affecting the optical signal reception communication effect.

[0003] At present, for the influence of atmospheric channels on wavefront distortion of wireless optical communications, the current mainstream targeted optical communication channel repair methods are all based on optical means to repair wavefront distortion. Summary of the invention

[0004] In view of this, the present invention provides a wireless coherent optical communication link signal equalization system. The present invention has the advantages of low complexity, high automation, fast response speed and easy implementation.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A wireless coherent optical communication link signal equalization system comprises an optical antenna, an optical wavefront detector, an optical coupler, an optical mixer, a local oscillator laser source, an optical detector, an optical wavefront resolver, an optical signal demodulator and an optical signal demodulation controller;

[0007] The optical antenna processes the optical signal through beam shaping, beam expansion, beam convergence, light splitting and light filtering on the optical path, and then guides the optical signal along the designed angle to the fixed end faces of the optical wavefront detector and the optical coupler respectively;

[0008] The optical wavefront detector transmits the detected wavefront information to the optical wavefront solver through the communication interface; the optical wavefront solver transmits the solved wavefront phase distribution parameters to the optical signal demodulator through the communication interface; the communication interface is an optical fiber or electrical communication interface;

[0009] The optical mixer is connected to the optical coupler, the local oscillator laser source and the optical detector respectively through optical fibers; the optical coupler transmits the coupled received optical signal to the optical mixer through the optical fiber; the local oscillator laser source transmits the local oscillator light to the optical mixer through the optical fiber; the optical mixer mixes the received optical signal with the local oscillator light and outputs the mixed signal to the optical detector through the optical fiber; the optical fiber is a single-mode optical fiber or a single-mode polarization-maintaining optical fiber;

[0010] Among them, the optical signal demodulation controller is connected to the optical wavefront solver, the optical signal demodulator, and the local oscillator laser source through a communication interface; the optical signal demodulation controller transmits the control signal to the optical wavefront solver, the optical signal demodulator or the local oscillator laser source through the communication interface; the optical signal demodulation controller receives the feedback signal from the optical wavefront solver, the optical signal demodulator or the local oscillator laser source through the communication interface.

[0011] Furthermore, the optical antenna has the functions of receiving an optical signal from an external free space, and performing beam expansion, beam convergence, beam shaping, light splitting, and light filtering on the spatial optical signal in the optical antenna; the optical antenna structure adopts a transmission structure, a reflection structure, or a combination of transmission and reflection structures;

[0012] The optical wavefront detector has the function of resolving the optical wavefront distortion of spatial light and outputting the spatial light wavefront distortion information;

[0013] The optical coupler has the function of coupling spatial light into the optical fiber;

[0014] The optical mixer has the function of mixing the optical signal input through the optical fiber with the local oscillator laser and outputting the mixed signal;

[0015] The local oscillator laser source is a monochromatic laser source with the same wavelength as the incident spatial light signal or a wavelength with a small difference, and has the ability to mix with the incident light signal;

[0016] The optical detector is a detector for detecting the intensity information of the optical signal. The detection range of the optical detector covers the wavelength of the incident light, the wavelength of the local oscillator light, and the wavelength of the difference frequency signal light mixed by the incident light and the local oscillator light. The working bandwidth of the optical detector exceeds the modulation bandwidth of the optical signal. The optical detector can be a single detector or a balanced detector.

[0017] The optical wavefront solver has the function of solving the optical wavefront distortion phase distribution information;

[0018] The optical signal demodulator has the functions of power amplification, analog-to-digital conversion, filtering, equalization and demodulation of the mixed optical signal.

[0019] The optical signal demodulation controller has the functions of controlling the working state, working temperature and power supply of the optical signal demodulator, the optical wavefront solver and the local oscillator laser source.

[0020] Furthermore, the specific process of realizing dynamic balancing of the optical communication link is as follows:

[0021] Step 1: The optical antenna receives the wireless optical signal from the free space, and after beam shaping, beam expansion, beam convergence, light splitting, and light filtering, transmits the optical signal to the optical wavefront detector and the optical coupler respectively;

[0022] Step 2, the optical wavefront detector receives the incident light signal after being processed by the optical antenna, and detects the wavefront distortion parameter of the light signal; the optical wavefront detector transmits the detected wavefront distortion parameter of the light signal to the optical wavefront solver through the communication interface; the optical wavefront solver calculates and obtains the wavefront distortion phase distribution information of the light signal; the optical wavefront solver transmits the wavefront distortion phase distribution information to the optical signal demodulator through the communication interface;

[0023] Step 3, the optical coupler receives the spatial optical signal transmitted by the optical antenna and couples the spatial optical signal into the optical fiber; the optical coupler transmits the optical signal to the optical mixer through the optical fiber; the local oscillator laser source transmits the optical signal to the optical mixer through the optical fiber; the optical mixer mixes the optical signal and the local oscillator light and outputs it to the optical detector through the optical fiber; the optical detector outputs the converted electrical signal to the optical signal demodulator;

[0024] Step 4, after the optical signal demodulator receives the electrical signal from the optical detector and the wavefront distortion phase distribution information from the optical wavefront resolver; the optical signal demodulator performs power amplification and analog-to-digital conversion on the electrical signal and converts it into a digital signal; the optical signal demodulator processes the digital signal according to the wavefront distortion phase distribution information, eliminates the phase noise effect caused by the wavefront distortion of the optical signal, and realizes balanced demodulation of the optical signal.

[0025] Furthermore, step 2 and step 3 are performed in parallel.

[0026] Furthermore, the optical signal demodulation controller receives working status information, working temperature information, and power supply status information from the optical signal demodulator, the optical wavefront solver, and the local oscillator laser source, and generates control instructions according to the corresponding information and forwards them to the corresponding working modules.

[0027] Compared with the prior art, the present invention has the following beneficial effects through the above technical solution:

[0028] The present invention adopts spatial optical wavefront detection means to assist in the real-time optical wavefront phase noise perception and assist in the dynamic balance of the coherent optical communication link. The present invention has low complexity, high automation, fast response speed and is easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of system connection of the present invention.

[0030] In the figure: 101 optical antenna, 102 optical wavefront detector, 103 optical coupler, 104 optical mixer, 105 local oscillator laser source, 106 optical detector, 107 optical wavefront resolver, 108 optical signal demodulator, 109 optical signal demodulation controller, 201 spatial optical path, 202 optical fiber, 203 communication interface. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0032] A wireless coherent optical communication equalization system 100 mainly includes an optical antenna 101, an optical wavefront detector 102, an optical coupler 103, an optical mixer 104, a local oscillator laser source 105, an optical detector 106, an optical wavefront resolver 107, an optical signal demodulator 108, and an optical signal demodulation controller 109. The optical signal mainly passes through two media, namely, a spatial optical path 201 and an optical fiber 202, and the electrical signal and the control signal mainly pass through a communication interface 203.

[0033] The optical antenna 101 can guide the optical signal along the designed angle to the fixed end faces of the wavefront detector 102 and the optical coupler 103 after necessary beam shaping, beam expansion, beam convergence, splitting and filtering on the optical path 201.

[0034] The optical wavefront detector 102 is connected to the optical wavefront solver 107 through the communication interface 203, and the optical wavefront detector 102 transmits the detected wavefront information to the optical wavefront solver 107 through the communication interface 203. The optical wavefront solver 107 is connected to the optical signal demodulator 108 through the communication interface 203, and the optical wavefront solver 107 transmits the resolved wavefront phase distribution parameters to the optical signal demodulator 108 through the communication interface 203. The communication interface 203 is an optical fiber or electrical communication interface.

[0035] The optical mixer 104 is connected to the optical coupler 103, the local oscillator laser source 105, and the optical detector 106 through the optical fiber 202. The optical coupler 103 transmits the coupled received optical signal to the optical mixer 104 through the optical fiber 202. The local oscillator laser source 105 transmits the optical signal to the optical mixer 104 through the optical fiber 202. The optical mixer 104 mixes the received optical signal with the local oscillator light and outputs the mixed signal to the optical detector 106 through the optical fiber 202. The optical fiber 202 is a single-mode optical fiber or a single-mode polarization-maintaining optical fiber.

[0036] The optical signal demodulation controller 109 is connected to the optical wavefront solver 107, the optical signal demodulator 108, and the local oscillator laser source 105 through the communication interface 203. The optical signal demodulation controller 109 transmits the control signal to the optical wavefront solver 107 or the optical signal demodulator 108 or the local oscillator laser source 105 through the communication interface 203. The optical signal demodulation controller 109 receives the feedback signal from the optical wavefront solver 107 or the optical signal demodulator 108 or the local oscillator laser source 105 through the communication interface 203. The communication interface 203 is an optical fiber or electrical communication interface.

[0037] like Figure 1 As shown, the wireless coherent optical communication link signal equalization technology comprises the following components:

[0038] The system comprises an optical antenna 101, an optical wavefront detector 102, an optical coupler 103, an optical mixer 104, a local oscillator laser source 105, an optical detector 106, an optical wavefront resolver 107, an optical signal demodulator 108, and an optical signal demodulation controller 109. The optical signal mainly passes through two media, namely, a spatial optical path 201 and an optical fiber 202, and the electrical signal and the control signal mainly pass through a communication interface 203.

[0039] The specific working steps of the wireless coherent optical communication link signal equalization technology are as follows:

[0040] Step 1: Receive and couple spatial optical signals

[0041] The optical antenna receives wireless optical signals from free space, and after necessary beam shaping, beam expansion, beam convergence, light splitting and light filtering, transmits the optical signals to the optical wavefront detector and optical coupler respectively.

[0042] Step 2: Receive and calculate optical wavefront distortion information

[0043] The optical wavefront detector receives the incident optical signal after being processed by the optical antenna, and detects the wavefront distortion parameter of the optical signal. The optical wavefront detector transmits the detected wavefront distortion parameter of the optical signal to the optical wavefront solver through the communication interface. The optical wavefront solver calculates and obtains the wavefront distortion phase distribution information of the optical signal. The optical wavefront solver transmits the wavefront distortion phase distribution information to the optical signal demodulator through the communication interface.

[0044] Step 3: Receive and mix the signal light and the local oscillator light and convert them into electrical signals

[0045] The optical coupler receives the spatial optical signal transmitted by the optical antenna and couples the spatial optical signal into the optical fiber. The optical coupler transmits the optical signal to the optical mixer through the optical fiber. The local oscillator laser source transmits the optical signal to the optical mixer through the optical fiber. The optical mixer mixes the optical signal and the local oscillator light and outputs it to the optical detector through the optical fiber. The optical detector outputs the converted electrical signal to the optical signal demodulator.

[0046] Step 4: Optical signal equalization and demodulation

[0047] The optical signal demodulator receives the electrical signal from the photodetector and the wavefront distortion phase distribution information from the optical wavefront solver. The optical signal demodulator performs necessary power amplification and analog-to-digital conversion on the electrical signal and converts it into a digital signal. The optical signal demodulator processes the digital signal according to the wavefront distortion phase distribution information, eliminates the phase noise effect caused by the optical signal wavefront distortion, and realizes balanced demodulation of the optical signal.

[0048] Step 5: Optical signal demodulation control

[0049] The optical signal demodulation controller receives working status information, working temperature information, and power supply status information from the optical signal demodulator, the optical wavefront solver, and the local oscillator laser source, and generates control instructions according to the corresponding information and forwards them to the corresponding working modules.

[0050] The step 1 is performed before the step 2, step 3 and step 4. The step 5 is performed during the whole process. The step 2 and step 3 can be performed at the same time. The step 4 is performed after the step 2 and step 3.

Claims

1. A wireless coherent optical communication link signal equalization system, characterized in that: It includes an optical antenna, an optical wavefront detector, an optical coupler, an optical mixer, a local oscillator laser source, an optical detector, an optical wavefront solver, an optical signal demodulator and an optical signal demodulation controller; The optical antenna processes the optical signal through beam shaping, beam expansion, beam convergence, light splitting and light filtering on the optical path, and then guides the optical signal along the designed angle to the fixed end faces of the optical wavefront detector and the optical coupler respectively; The optical wavefront detector transmits the detected wavefront information to the optical wavefront solver through the communication interface; the optical wavefront solver transmits the solved wavefront phase distribution parameters to the optical signal demodulator through the communication interface; the communication interface is an optical fiber or electrical communication interface; The optical mixer is connected to the optical coupler, the local oscillator laser source and the optical detector respectively through optical fibers; the optical coupler transmits the coupled received optical signal to the optical mixer through the optical fiber; the local oscillator laser source transmits the local oscillator light to the optical mixer through the optical fiber; the optical mixer mixes the received optical signal with the local oscillator light and outputs the mixed signal to the optical detector through the optical fiber; the optical fiber is a single-mode optical fiber or a single-mode polarization-maintaining optical fiber; The optical signal demodulation controller is connected to the optical wavefront solver, the optical signal demodulator, and the local oscillator laser source through a communication interface; the optical signal demodulation controller transmits a control signal to the optical wavefront solver, the optical signal demodulator, or the local oscillator laser source through the communication interface; the optical signal demodulation controller receives a feedback signal from the optical wavefront solver, the optical signal demodulator, or the local oscillator laser source through the communication interface; The optical antenna has the functions of receiving an optical signal from an external free space, and performing beam expansion, beam convergence, beam shaping, light splitting, and light filtering on the spatial optical signal in the optical antenna; the optical antenna structure adopts a transmission structure, a reflection structure, or a combination of transmission and reflection structures; The optical wavefront detector has the function of resolving the optical wavefront distortion of spatial light and outputting the spatial light wavefront distortion information; The optical coupler has the function of coupling spatial light into the optical fiber; The optical mixer has the function of mixing the optical signal input through the optical fiber with the local oscillator laser and outputting the mixed signal; The local oscillator laser source is a monochromatic laser source with the same wavelength as the incident spatial light signal or a wavelength with a small difference, and has the ability to mix with the incident light signal; The optical detector is a detector for detecting the intensity information of the optical signal. The detection range of the optical detector covers the wavelength of the incident light, the wavelength of the local oscillator light, and the wavelength of the difference frequency signal light mixed by the incident light and the local oscillator light. The working bandwidth of the optical detector exceeds the modulation bandwidth of the optical signal. The optical detector can be a single detector or a balanced detector. The optical wavefront solver has the function of solving the optical wavefront distortion phase distribution information; The optical signal demodulator has the functions of power amplification, analog-to-digital conversion, filtering, equalization and demodulation of the mixed optical signal. The optical signal demodulation controller has the function of controlling the working state, working temperature and power supply of the optical signal demodulator, the optical wavefront solver and the local oscillator laser source; The specific process of achieving dynamic balancing of optical communication links is as follows: Step 1: The optical antenna receives the wireless optical signal from the free space, and after beam shaping, beam expansion, beam convergence, light splitting, and light filtering, transmits the optical signal to the optical wavefront detector and the optical coupler respectively; Step 2, the optical wavefront detector receives the incident light signal after being processed by the optical antenna, and detects the wavefront distortion parameter of the light signal; the optical wavefront detector transmits the detected wavefront distortion parameter of the light signal to the optical wavefront solver through the communication interface; the optical wavefront solver calculates and obtains the wavefront distortion phase distribution information of the light signal; the optical wavefront solver transmits the wavefront distortion phase distribution information to the optical signal demodulator through the communication interface; Step 3, the optical coupler receives the spatial optical signal transmitted by the optical antenna and couples the spatial optical signal into the optical fiber; the optical coupler transmits the optical signal to the optical mixer through the optical fiber; the local oscillator laser source transmits the optical signal to the optical mixer through the optical fiber; the optical mixer mixes the optical signal and the local oscillator light and outputs it to the optical detector through the optical fiber; the optical detector outputs the converted electrical signal to the optical signal demodulator; Step 4, after the optical signal demodulator receives the electrical signal from the optical detector and the wavefront distortion phase distribution information from the optical wavefront resolver; the optical signal demodulator performs power amplification and analog-to-digital conversion on the electrical signal and converts it into a digital signal; the optical signal demodulator processes the digital signal according to the wavefront distortion phase distribution information, eliminates the phase noise effect caused by the wavefront distortion of the optical signal, and realizes balanced demodulation of the optical signal.

2. A wireless coherent optical communication link signal equalization system according to claim 1, characterized in that: The steps 2 and 3 are performed in parallel.

3. A wireless coherent optical communication link signal equalization system according to claim 1, characterized in that: The optical signal demodulation controller receives working status information, working temperature information, and power supply status information from the optical signal demodulator, the optical wavefront solver, and the local oscillator laser source, and generates control instructions according to the corresponding information and forwards them to the corresponding working modules.

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