CN118138140B - Multi-aperture coherent synthesis laser communication system and method based on circular offset keying modulation - Google Patents
Multi-aperture coherent synthesis laser communication system and method based on circular offset keying modulation Download PDFInfo
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Abstract
The invention provides a multi-aperture coherent synthesis laser communication system and a method based on circular offset keying modulation, wherein the method is applied to the multi-aperture coherent synthesis laser communication system based on circular offset keying modulation, which comprises an FSOC transmitter and a multi-aperture space diversity receiver, and comprises the steps that the FSOC transmitter generates FSOC signal light, performs CPolSK modulation on the FSOC signal light to obtain emission light, and sends the emission light to the multi-aperture space diversity receiver; the multi-aperture space diversity receiver receives the emitted light, carries out self-adaptive coupling on the emitted light and carries out coherent combination on the emitted light to obtain multi-aperture coherent combination laser, and carries out demodulation output on the multi-aperture coherent combination laser. The invention can realize high-efficiency stable communication under the complex atmospheric condition and optimize the performance of the FSOC system under the complex atmospheric condition. The invention adopts CPolSK modulation technology and multi-aperture coherent synthesis technology to effectively improve the turbulence resistance of the FSOC system.
Description
Technical Field
The invention relates to the technical field of free space optical communication, in particular to a multi-aperture coherent synthesis laser communication system and method based on circular offset keying modulation.
Background
Free Space Optical Communication (FSOC) is favored as an important communication method, and has advantages of large transmission data amount, rapid transmission, high transmission accuracy, and the like. However, the performance of FSOC systems is largely limited by wavefront aberrations caused by atmospheric turbulence. The distortion can cause a series of problems such as spot drift, light intensity flickering, signal depth attenuation and the like, the error rate of the system is obviously increased, and even the communication link is possibly interrupted when the error rate is serious. While the use of Adaptive Optics (AO) techniques and multi-aperture spatially diverse reception systems can alleviate these problems to some extent, they have limited performance under highly turbulent conditions.
Disclosure of Invention
Accordingly, there is a need for providing a multi-aperture coherent combining laser communication system and method based on circular shift keying modulation.
The multi-aperture coherent synthesis laser communication method based on the circular offset keying modulation is applied to a multi-aperture coherent synthesis laser communication system based on the circular offset keying modulation, which comprises an FSOC transmitter and a multi-aperture space diversity receiver, and comprises the following steps:
the FSOC transmitter generates FSOC signal light, carries out CPolSK modulation on the FSOC signal light to obtain emission light, and sends the emission light to the multi-aperture space diversity receiver;
the multi-aperture space diversity receiver receives the emitted light, performs self-adaptive coupling on the emitted light and performs coherent combination on the emitted light to obtain multi-aperture coherent combination laser, and demodulates and outputs the multi-aperture coherent combination laser.
In one embodiment, the FSOC transmitter comprises a laser transmitter, a first PBS, a first PBC, a first QWP, a fiber optic amplifier and a collimator;
The laser transmitter transmits FSOC signal light, and the FSOC signal light passes through the first PBS to obtain two mutually orthogonal first polarized lights;
carrying out phase modulation on any beam of first polarized light to obtain modulated polarized light, and sending the modulated polarized light and the other beam of first polarized light to the first PBC;
the first PBC receives the modulated polarized light and the other beam of first polarized light to obtain first linearly polarized light, and the first linearly polarized light is sent to the first QWP;
the first QWP receives the first linearly polarized light to obtain first circularly polarized light, and sends the first circularly polarized light to the optical fiber amplifier;
the optical fiber amplifier amplifies the first circularly polarized light to obtain processed circularly polarized light, and the processed circularly polarized light is sent to the collimator to obtain emitted light.
In one embodiment, the multi-aperture spatial diversity receiver comprises an adaptive fiber coupler array, a plurality of first phase modulators, a plurality of second QWPs, a plurality of second PBSs, a plurality of second PBCs, a first photodetector, a second photodetector, a first amplifier, a second amplifier, a first subtractor and a first piston phase error control module;
The self-adaptive optical fiber coupler array receives the emitted light, performs aperture division on the emitted light to obtain diversity signal light, couples the diversity signal light to a coupling optical fiber, and sends the diversity signal light to the first phase modulator through the coupling optical fiber;
the first phase modulator corresponds to the second QWP one by one, receives the diversity signal light, performs piston phase error compensation on the diversity signal light to obtain first co-phase circularly polarized light, and sends the first co-phase circularly polarized light to the second QWP;
The second QWP receives the first co-phase circularly polarized light to obtain second linearly polarized light, and sends the second linearly polarized light to the second PBS;
The second PBS receives the second linearly polarized light to obtain mutually orthogonal first polarized light, and the first polarized light is sent to the second PBC;
The second PBC performs coherent combination on the light with the same first polarization state to obtain two first combined beams, any one of the first combined beams is sent to the first photoelectric detector, and the other first combined beam is sent to the second photoelectric detector;
The first photoelectric detector receives the arbitrary first composite beam, detects the beam intensity of the arbitrary first composite beam, and simultaneously sends the arbitrary first composite beam to the first amplifier;
the second photoelectric detector receives the other first combined beam, detects the beam intensity of the other first combined beam, and simultaneously sends the other first combined beam to the second amplifier;
The first amplifier amplifies the signal of any one of the first composite beams to obtain a first amplified signal, and the first amplified signal is sent to the first subtracter;
The second amplifier amplifies the signal of the other first combined beam to obtain a second amplified signal, and the second amplified signal is sent to the first subtracter;
The first subtracter receives the first amplified signal and the second amplified signal to obtain a first differential signal, and demodulates the first amplified signal and the second amplified signal according to the first differential signal to obtain a first demodulation multi-aperture coherent combination laser;
the first piston phase error control module is arranged between the first subtracter and the first phase modulator, and adjusts the piston phase error between the first phase controller and different diversity signal lights according to the first amplified signal and the second amplified signal in the first subtracter.
In one embodiment, the multi-aperture spatially diverse receiver comprises an adaptive fiber coupler array, a plurality of third QWPs, a plurality of second phase modulators, a plurality of third PBSs, a plurality of third PBCs, a third photodetector, a fourth photodetector, a third amplifier, a fourth amplifier, and a second subtractor;
the self-adaptive optical fiber coupler array receives the emitted light, performs aperture division on the emitted light to obtain diversity signal light, couples the diversity signal light to a coupling optical fiber, and sends the diversity signal light to the third QWP through the coupling optical fiber;
The third QWP receives the diversity signal light to obtain third linearly polarized light, and sends the third linearly polarized light to the third PBS;
the third PBS receives the third linearly polarized light to obtain mutually orthogonal second polarized light, and the second polarized light is sent to the second phase modulator;
The second phase modulator receives the second polarized light, performs piston phase error compensation on the second polarized light to obtain second co-phase circularly polarized light, and sends the second co-phase circularly polarized light to the third PBC;
The third PBC carries out coherent combination on the same second co-phase circularly polarized light to obtain two second combined beams, any one of the second combined beams is sent to the third photoelectric detector, and the other second combined beam is sent to the fourth photoelectric detector;
The third photoelectric detector receives the arbitrary second combined beam, detects the beam intensity of the arbitrary second combined beam, and simultaneously sends the arbitrary second combined beam to a third amplifier;
The fourth photoelectric detector receives the other second combined beam, detects the beam intensity of the other second combined beam, and simultaneously sends the other second combined beam to a fourth amplifier;
The third amplifier amplifies the signal of any one of the second combined beams to obtain a third amplified signal, and the third amplified signal is sent to the second subtracter;
The fourth amplifier amplifies the signal of the other second composite beam to obtain a fourth amplified signal, and the fourth amplified signal is sent to the second subtracter;
the second subtracter receives the third amplified signal and the fourth amplified signal to obtain a second differential signal, and demodulates the third amplified signal and the fourth amplified signal according to the second differential signal to obtain a second demodulation multi-aperture coherent combination laser.
In one embodiment, the multi-aperture space diversity receiver further comprises a plurality of third phase modulators;
The third phase modulator is arranged between the third PBCs and on the propagation route of the third composite light beam, and performs piston phase error compensation on the third composite light beam.
In one embodiment, the system further comprises a plurality of fourth QWPs;
The fourth QWP is arranged between the third PBC and the third and fourth photodetectors, receives the second synthesized light beam to obtain fourth linearly polarized light, and sends the fourth linearly polarized light to the third and fourth photodetectors.
In one embodiment, the device further comprises a fourth photodetector, a tilt aberration control module and a high voltage amplifier;
the aperture segmentation is carried out on the emitted light to obtain diversity signal light, and then the method further comprises the following steps:
The fourth photoelectric detector receives the diversity signal light, detects the beam intensity of the diversity signal light and simultaneously sends the diversity signal light to the oblique aberration control module;
the tilt aberration control module receives the diversity signal light, generates random control voltage according to the diversity signal light, sends the random control voltage to the high-voltage amplifier to obtain amplified voltage, and sends the amplified voltage to the adaptive optical fiber coupler array to ensure that the optical fiber coupling efficiency of the diversity signal light reaches the maximum power.
In one embodiment, the system further comprises a second piston phase error control module and a third piston phase error control module;
The second piston phase error control module is arranged between the third amplifier and the second phase modulator, and adjusts second piston phase errors between the second phase controller and different second co-phase circularly polarized lights according to the third amplified signal in the third amplifier;
The third piston phase error control module is arranged between the fourth amplifier and the second phase modulator, and adjusts second piston phase errors between the second phase controller and different second co-phase circularly polarized lights according to the fourth amplified signal in the fourth amplifier.
In one embodiment, the device further comprises a fourth piston phase error control module and a fifth piston phase error control module;
The fourth piston phase error control module is arranged between the third amplifier and the third phase modulator, and adjusts third piston phase errors of the third phase controller to different third composite beams according to the third amplified signals in the third amplifier;
the third piston phase error control module is arranged between the fourth amplifier and the second phase modulator, and adjusts second piston phase errors of the third phase controller to different third composite beams according to the fourth amplified signal in the fourth amplifier.
A multi-aperture coherent synthesis laser communication system based on circular offset keying modulation comprises an FSOC transmitter and a multi-aperture space diversity receiver;
the FSOC transmitter generates FSOC signal light, carries out CPolSK modulation on the FSOC signal light to obtain emission light, and sends the emission light to the multi-aperture space diversity receiver;
the multi-aperture space diversity receiver receives the emitted light, performs self-adaptive coupling on the emitted light and performs coherent combination on the emitted light to obtain multi-aperture coherent combination laser, and demodulates and outputs the multi-aperture coherent combination laser.
Compared with the prior art, the invention has the advantages that the invention can realize high-efficiency stable communication under complex atmospheric conditions, and optimize the performance of the FSOC system under complex atmospheric conditions, especially under strong atmospheric turbulence environment. The invention adopts CPolSK modulation technology and multi-aperture coherent synthesis technology, and realizes signal light CPolSK modulation, coherent polarization synthesis receiving and demodulation through the specially designed optical antenna assembly, thereby effectively improving the turbulence resistance of the FSOC system.
Drawings
FIG. 1 is a flow chart of a multi-aperture coherent combining laser communication method based on circular shift keying modulation in one embodiment;
FIG. 2 is a schematic diagram of an FSOC transmitter process flow in one embodiment;
FIG. 3 is a schematic diagram of a process flow of a multi-aperture spatially diverse receiver in one embodiment;
FIG. 4 is a schematic diagram of a second phase modulator mounting structure in one embodiment;
FIG. 5 is a schematic diagram of a third phase modulator mounting structure in one embodiment;
FIG. 6 is a schematic diagram of a fourth QWP mounting structure in one embodiment;
Fig. 7 is a schematic structural diagram of a multi-aperture coherent combining laser communication system based on circular offset keying modulation in one embodiment.
In the figure, a 10-FSOC transmitter, an 11-multi-aperture space diversity receiver, a 100-laser transmitter, a 101-first PBS, a 102-first PBC, a 103-first QWP, a 104-fiber amplifier, a 105-collimator, a 110-adaptive fiber coupler array, a 111-first phase modulator, a 112-second QWP, a 113-second PBS, a 114-second PBC, a 115-first photodetector, a 116-second photodetector, a 117-first amplifier, a 118-second amplifier, a 119-first subtractor, a 1110-first piston phase error control module, a 112' -third PBC, a 111' -second phase modulator, a 113' -third PBS, a 114' -third PBC, a 115' -third photoelectric detector, a 116' -fourth photoelectric detector, a 117' -third amplifier, a 118' -fourth amplifier, a 119' -second subtractor, a 1111-fourth photoelectric detector, a-tilt aberration control module, a 1113-high voltage amplifier, a fourth piston error control module, a 1116-fourth piston error control module, a third piston error control module, a fourth piston error control module, a 11117-fourth piston error control module, a fifth piston error control module, a 1115, a third piston error control module, and a third piston error control module are shown
Detailed Description
Before proceeding with the description of the embodiments of the present invention, the general inventive concept will be described as follows:
The invention is mainly developed in the free space optical communication process, and the performance of the current FSOC system is limited to a great extent by wavefront distortion caused by atmospheric turbulence. The distortion can cause a series of problems such as spot drift, light intensity flickering, signal depth attenuation and the like, the error rate of the system is obviously increased, and even the communication link is possibly interrupted when the error rate is serious. While the use of Adaptive Optics (AO) techniques and multi-aperture spatially diverse reception systems can alleviate these problems to some extent, they have limited performance under highly turbulent conditions.
The selection and optimization of the modulation mode of the FSOC system becomes a key breakthrough point for improving the anti-turbulence interference capability of the system. CPolSK (Circular Polarization SHIFT KEYING) modulation mode is a modulation technique that uses the change in circular polarization to transmit information, and the encoding and transmission of information is achieved by changing the circular polarization of the transmitted signal. CPolSK modulation has better turbulence resistance than traditional modulation modes. For example, under the same constraint, the SNR requirement of CPolSK modulation is reduced by 8dB compared to OOK modulation. However, to fully exploit the potential of CPolSK modulation modes, special optical antenna systems, including those of special optical transmitters and receivers, must be designed to further enhance the turbulence resistance of CPolSK modulation modes. Therefore, the invention provides a multi-aperture coherent synthesis laser communication method based on circular polarization keying modulation, which is applied to a multi-aperture coherent synthesis laser communication system based on circular polarization keying modulation, and by designing a corresponding FSO transmitter and a multi-aperture space diversity receiver, CPolSK modulation signal generation and reception under an atmosphere channel are realized, and the turbulence resistance performance of the communication system is improved.
Having described the general inventive concept, the present invention will be further described in detail with reference to the accompanying drawings by way of specific embodiments thereof, in order to make the objects, technical solutions and advantages of the present invention more apparent.
It should be noted that unless otherwise defined, technical or scientific terms used in one or more embodiments of the present specification should be given the ordinary meaning as understood by one of ordinary skill in the art to which the present invention pertains. The use of the terms "first," "second," and the like in one or more implementations of the present description does not denote any order, quantity, or importance, but rather the terms "first," "second," and the like are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof, but does not exclude other elements or items. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", etc. are used merely to indicate relative positional relationships, which may also be changed when the absolute position of the object to be described is changed.
For convenience of understanding, the terms involved in the embodiments of the present invention are explained below:
FSOC free space optical communication (FREE SPACE Optical Communica tions) refers to a communication technology in which light waves are used as carriers to transmit information in vacuum or atmosphere. The communication method can be divided into atmospheric optical communication, inter-satellite optical communication and satellite-ground optical communication.
CPolSK modulation circular polarization keying (Polarization SHIFT KEYING, POLSK) is a modulation technique that uses the change in circular polarization to transmit information, and the encoding and transmission of information is achieved by changing the circular polarization of the transmitted signal.
And the PBC is used for combining two mutually perpendicular polarized light beams (p polarization and s polarization) based on the characteristics of polarized light.
PBS, polarization beam splitter, also known as polarization splitting prism, refers to an optical device for coupling orthogonal linearly polarized light in one fiber to output in two fibers, respectively.
QWP: quarter wave plate is also known as a "quarter wave plate". When light with a certain wavelength passes through the light guide plate at normal incidence, the phase difference between the emergent ordinary light and the abnormal light is 1/4 wavelength. It is often used to change linearly polarized light into circularly or elliptically polarized light in the light path, or vice versa.
In one embodiment, as shown in fig. 1, a multi-aperture coherent combining laser communication method based on circular offset keying modulation is provided, and the method is applied to a multi-aperture coherent combining laser communication system based on circular offset keying modulation, which includes an FSOC transmitter 10 and a multi-aperture space diversity receiver 11, and includes the following steps:
In step S101, the FSOC transmitter generates FSOC signal light, modulates CPolSK the FSOC signal light to obtain emission light, and sends the emission light to the multi-aperture space diversity receiver.
Specifically, the FSOC transmitter 10 generates FSOC signal light, modulates CPolSK the FSOC signal light to obtain emission light, transmits the emission light to the transmission in the atmospheric channel, and transmits the emission light to the multi-aperture space diversity receiver 11 through the atmospheric channel.
On this basis, the FSOC transmitter comprises a laser transmitter, a first PBS, a first PBC, a first QWP, a fiber optic amplifier and a collimator;
The laser transmitter transmits FSOC signal light, and the FSOC signal light passes through the first PBS to obtain two mutually orthogonal first polarized lights;
carrying out phase modulation on any beam of first polarized light to obtain modulated polarized light, and sending the modulated polarized light and the other beam of first polarized light to the first PBC;
the first PBC receives the modulated polarized light and the other beam of first polarized light to obtain first linearly polarized light, and the first linearly polarized light is sent to the first QWP;
the first QWP receives the first linearly polarized light to obtain first circularly polarized light, and sends the first circularly polarized light to the optical fiber amplifier;
the optical fiber amplifier amplifies the first circularly polarized light to obtain processed circularly polarized light, and the processed circularly polarized light is sent to the collimator to obtain emitted light.
Specifically, as shown in FIG. 2, in the FSOC transmitter 10, there are included a laser transmitter 100, a first PBS101, a first PBC102, a first QWP103, a fiber optic amplifier 104 and a collimator 105;
The FSOC signal light is transmitted by the laser transmitter 100, passes through the first PBS101, and is split into two orthogonal X and Y first polarized light components by the FSOC signal light rotated 45 ° from the optical axis. Wherein any one of the first polarized light is subjected to phase modulation by the encoded data, so that the laser phase is rotated by 0 or pi. After passing through the first PBC102 (polarization beam combiner), the two orthogonal signal lights are combined into first linearly polarized lights with different polarization directions of 45 °/-45 °, the first linearly polarized lights are changed into right/left first circularly polarized lights through the first QWP103 (1/4 wave plate), the first circularly polarized lights are sent to the optical fiber amplifier 104, the optical fiber amplifier 104 amplifies the first circularly polarized lights, and then the obtained processed circularly polarized lights are sent to the collimator 105, so as to obtain emission lights, and then the emission lights are sent to the air channel through the collimator 105 for transmission.
Step S102, the multi-aperture space diversity receiver receives the emitted light, adaptively couples and coherently synthesizes the emitted light to obtain multi-aperture coherent synthesis laser, and demodulates and outputs the multi-aperture coherent synthesis laser.
Specifically, the multi-aperture spatial diversity receiver 11 receives the emitted light, adaptively couples the emitted light, coherently synthesizes the same, and then demodulates and outputs the same.
In this embodiment, the multi-aperture space diversity receiver not only can identify the polarization state, but also has a multi-aperture coherent combining function, so as to improve the power of the received signal and reduce the jitter degree. The multi-aperture space diversity receiving technology can be used for efficiently receiving and demodulating the signal light, and demodulating and outputting the signal light after multi-aperture coherent synthesis to obtain the demodulation multi-aperture coherent synthesis laser.
On this basis, in one embodiment, the multi-aperture space diversity receiver comprises an adaptive fiber coupler array, a plurality of first phase modulators, a plurality of second QWPs, a plurality of second PBSs, a plurality of second PBCs, a first photodetector, a second photodetector, a first amplifier, a second amplifier, a first subtractor and a first piston phase error control module;
The self-adaptive optical fiber coupler array receives the emitted light, performs aperture division on the emitted light to obtain diversity signal light, couples the diversity signal light to a coupling optical fiber, and sends the diversity signal light to the first phase modulator through the coupling optical fiber;
the first phase modulator corresponds to the second QWP one by one, receives the diversity signal light, performs piston phase error compensation on the diversity signal light to obtain first co-phase circularly polarized light, and sends the first co-phase circularly polarized light to the second QWP;
The second QWP receives the first co-phase circularly polarized light to obtain second linearly polarized light, and sends the second linearly polarized light to the second PBS;
The second PBS receives the second linearly polarized light to obtain mutually orthogonal first polarized light, and the first polarized light is sent to the second PBC;
The second PBC performs coherent combination on the light with the same first polarization state to obtain two first combined beams, any one of the first combined beams is sent to the first photoelectric detector, and the other first combined beam is sent to the second photoelectric detector;
The first photoelectric detector receives the arbitrary first composite beam, detects the beam intensity of the arbitrary first composite beam, and simultaneously sends the arbitrary first composite beam to the first amplifier;
the second photoelectric detector receives the other first combined beam, detects the beam intensity of the other first combined beam, and simultaneously sends the other first combined beam to the second amplifier;
The first amplifier amplifies the signal of any one of the first composite beams to obtain a first amplified signal, and the first amplified signal is sent to the first subtracter;
The second amplifier amplifies the signal of the other first combined beam to obtain a second amplified signal, and the second amplified signal is sent to the first subtracter;
The first subtracter receives the first amplified signal and the second amplified signal to obtain a first differential signal, and demodulates the first amplified signal and the second amplified signal according to the first differential signal to obtain a first demodulation multi-aperture coherent combination laser;
the first piston phase error control module is arranged between the first subtracter and the first phase modulator, and adjusts the piston phase error between the first phase controller and different diversity signal lights according to the first amplified signal and the second amplified signal in the first subtracter.
Specifically, as shown in FIG. 3, the multi-aperture spatial diversity receiver 11 includes an adaptive fiber coupler array 110, a plurality of first phase modulators 111, a plurality of second QWPs 112, a plurality of second PBSs 113, a plurality of second PBCs 114, a first photodetector 115, a second photodetector 116, a first amplifier 117, a second amplifier 118, a first subtractor 119, and a first piston phase error control module 1110.
The multi-aperture space diversity receiver 11 performs aperture division on the received optical signal through an optical cutting array to obtain a plurality of diversity signal optical beams, and adopts a control algorithm to couple the diversity signal light into the coupling optical fibers corresponding to the adaptive optical fiber couplers through the adaptive optical fiber coupler array 110.
The coupling optical fiber is correspondingly connected with a first phase modulator 111, the first phase modulator 111 adopts a control algorithm to carry out piston phase error compensation on the phase error between each path of optical signals by taking the intensity of the differential signal as an evaluation standard, so as to obtain first co-phase circularly polarized light and realize the phase alignment of diversity signals.
The first phase modulator 111 converts the co-phase circularly polarized light into second linearly polarized light through the second QWP112 (1/4 wave plate) first, converts the co-phase circularly polarized light in the right/left direction into second linearly polarized light of 45 °/-45 °, then divides the polarization direction of the second linearly polarized light into orthogonal X and Y polarization directions by the second PBS113 (polarization beam splitter) to obtain first polarized light, and performs coherent polarization synthesis on the same first polarized light through the second PBC114 (polarization beam combiner) to output the same first polarized light as one beam of light, so as to obtain two beams of first synthesized light.
The two first combined beams are respectively connected to the first photodetector 115 and the second photodetector 116, and the first photodetector 115 and the second photodetector 116 detect the intensities of the two first combined beams corresponding to the 45 °/-45 ° second linearly polarized light. The first combined beam is converted from an optical signal into an electrical signal after passing through the first photodetector 115 and the second photodetector 116, and the two first combined beams are respectively transmitted to the first amplifier 117 and the second amplifier 118 to be amplified. The two amplified first amplified signals and the second amplified signals may be used to generate differential signals by the first subtractor 119 to demodulate signal light in CPolSK modulation modes.
The first piston phase error control module 1110 is disposed between the first subtractor 119 and the first phase modulator 111, and adjusts the piston phase error between the first phase controller 111 for different diversity signal lights according to the first amplified signal and the second amplified signal in the first subtractor 119.
On this basis, in one embodiment, the multi-aperture spatial diversity receiver comprises an adaptive fiber coupler array, a plurality of third QWPs, a plurality of second phase modulators, a plurality of third PBSs, a plurality of third PBCs, a third photodetector, a fourth photodetector, a third amplifier, a fourth amplifier, and a second subtractor;
the self-adaptive optical fiber coupler array receives the emitted light, performs aperture division on the emitted light to obtain diversity signal light, couples the diversity signal light to a coupling optical fiber, and sends the diversity signal light to the third QWP through the coupling optical fiber;
The third QWP receives the diversity signal light to obtain third linearly polarized light, and sends the third linearly polarized light to the third PBS;
the third PBS receives the third linearly polarized light to obtain mutually orthogonal second polarized light, and the second polarized light is sent to the second phase modulator;
The second phase modulator receives the second polarized light, performs piston phase error compensation on the second polarized light to obtain second co-phase circularly polarized light, and sends the second co-phase circularly polarized light to the third PBC;
The third PBC carries out coherent combination on the same second co-phase circularly polarized light to obtain two second combined beams, any one of the second combined beams is sent to the third photoelectric detector, and the other second combined beam is sent to the fourth photoelectric detector;
The third photoelectric detector receives the arbitrary second combined beam, detects the beam intensity of the arbitrary second combined beam, and simultaneously sends the arbitrary second combined beam to a third amplifier;
The fourth photoelectric detector receives the other second combined beam, detects the beam intensity of the other second combined beam, and simultaneously sends the other second combined beam to a fourth amplifier;
The third amplifier amplifies the signal of any one of the second combined beams to obtain a third amplified signal, and the third amplified signal is sent to the second subtracter;
The fourth amplifier amplifies the signal of the other second composite beam to obtain a fourth amplified signal, and the fourth amplified signal is sent to the second subtracter;
the second subtracter receives the third amplified signal and the fourth amplified signal to obtain a second differential signal, and demodulates the third amplified signal and the fourth amplified signal according to the second differential signal to obtain a second demodulation multi-aperture coherent combination laser.
Specifically, as shown in FIG. 4, the multi-aperture spatially diverse receiver 11 may be composed of another structure including an adaptive fiber coupler array 110, a plurality of third QWPs 112', a second phase modulator 111', a plurality of third PBCs 113', a plurality of third PBCs 114', a third photodetector 115', a fourth photodetector 116', a third amplifier 117', a fourth amplifier 118', and a second subtractor 119'.
The multi-aperture space diversity receiver 11 performs aperture division on the received optical signal through an optical cutting array to obtain a plurality of diversity signal optical beams, and adopts a control algorithm to couple the diversity signal light into the coupling optical fibers corresponding to the adaptive optical fiber couplers through the adaptive optical fiber coupler array 110.
The coupling optical fiber is correspondingly connected with a third QWP112', the second QWP112' (1/4 wave plate) is converted into third linearly polarized light, the co-phase circularly polarized light in the right/left direction is converted into third linearly polarized light of 45 degrees/45 degrees, then the third linearly polarized light is sent to a third PBS113' (polarization beam splitter), the polarization direction of the third linearly polarized light is divided into orthogonal X and Y polarization directions by the third PBS113', second polarized light is obtained, the second polarized light is sent to a second phase modulator 111', the second phase modulator 111' receives the second polarized light, piston phase error compensation is carried out on the second polarized light, second co-phase circularly polarized light is obtained, and coherent polarization synthesis is carried out on the same first polarized light through a third PBC114' (polarization beam combiner), so that two second synthesized beams are obtained.
The two second combined beams are respectively connected to a third photodetector 115 'and a fourth photodetector 116', and the third photodetector 115 'and the fourth photodetector 116' detect the intensities of the two second combined beams corresponding to the 45 °/-45 ° third linearly polarized light. The second combined beam is converted from an optical signal into an electrical signal after passing through the third photodetector 115 'and the fourth photodetector 116', and the two second combined beams are respectively transmitted to the third amplifier 117 'and the fourth amplifier 118' for electrical signal amplification. The third amplified signal and the fourth amplified signal obtained by the two-beam amplification may be generated by the second subtractor 119' to generate a differential signal to demodulate the signal light of CPolSK modulation modes.
On this basis, in one embodiment, the multi-aperture space diversity receiver further comprises a plurality of third phase modulators;
The third phase modulator is arranged between the third PBCs and on the propagation route of the third composite light beam, and performs piston phase error compensation on the third composite light beam.
Specifically, as shown in fig. 5, the multi-aperture space diversity receiver 11 may be configured such that a second-stage phase modulator, that is, a third phase modulator 1117, is disposed in the middle of the third PBC114', and the third phase modulator 1117 performs piston phase error compensation on the third composite beam.
In this embodiment, the multi-aperture space diversity receiver 11 may have various structures, a primary phase modulator may be disposed between the third PBS113 'and the third PBC114', and a secondary phase modulator may be disposed between the third PBS113 'and the third PBC114' and between the third PBC114 'and the third PBC114', so that the structure has flexibility and can meet the complex optical transmission and processing requirements.
The provision of the third phase modulator 1117 can further reduce phase noise and interference, and improve signal quality and transmission reliability.
On the basis, the device also comprises a fourth QWP;
The fourth QWP is arranged between the third PBC and the third and fourth photodetectors, receives the second synthesized light beam to obtain fourth linearly polarized light, and sends the fourth linearly polarized light to the third and fourth photodetectors.
Specifically, as shown in fig. 6, the multi-aperture space diversity receiver 11 may be configured such that a fourth QWP1114 is provided between the third PBC114' and the third photodetector 115' and the fourth photodetector 116 '.
In the present embodiment, the fourth QWP1114 is disposed between the third PBC114' and the third and fourth photodetectors 115' and 116', so that the signal transmission efficiency and stability can be improved.
The device also comprises a fourth photoelectric detector, an inclined aberration control module and a high-voltage amplifier;
the aperture segmentation is carried out on the emitted light to obtain diversity signal light, and then the method further comprises the following steps:
The fourth photoelectric detector receives the diversity signal light, detects the beam intensity of the diversity signal light and simultaneously sends the diversity signal light to the oblique aberration control module;
the tilt aberration control module receives the diversity signal light, generates random control voltage according to the diversity signal light, sends the random control voltage to the high-voltage amplifier to obtain amplified voltage, and sends the amplified voltage to the adaptive optical fiber coupler array to ensure that the optical fiber coupling efficiency of the diversity signal light reaches the maximum power.
Specifically, after the aperture division is performed on the emitted light to obtain the diversity signal light, the determination of the optical coupling power intensity of the diversity signal is required to perform the coupling of the coupling optical fibers. The fourth photodetector 1111 receives the diversity signal light, detects the beam intensity of the diversity signal light, and transmits the diversity signal light to the tilt aberration control module 1112.
The tilt aberration control module 1112 receives the diversity signal light, generates a random control voltage according to the diversity signal light, generates a control voltage signal, sends the random control voltage to the high-voltage amplifier 1113, amplifies the random control voltage by the high-voltage amplifier 1113 to obtain an amplified voltage, and sends the amplified voltage to the adaptive fiber coupler array 110, so that the fiber coupling efficiency of the diversity signal light reaches the optimal overall process, and performs fiber coupling.
The device also comprises a second piston phase error control module and a third piston phase error control module;
The second piston phase error control module is arranged between the third amplifier and the second phase modulator, and adjusts second piston phase errors between the second phase controller and different second co-phase circularly polarized lights according to the third amplified signal in the third amplifier;
The third piston phase error control module is arranged between the fourth amplifier and the second phase modulator, and adjusts second piston phase errors between the second phase controller and different second co-phase circularly polarized lights according to the fourth amplified signal in the fourth amplifier.
Specifically, the second piston phase error control module 1115 and the third piston phase error control module 1116 are respectively connected to the third amplifier 117' and the fourth amplifier 118', and adjust the second piston phase error between the second phase controller 111' and the different second co-phase circularly polarized light according to the third amplified signal and the fourth amplified signal.
The device also comprises a fourth piston phase error control module and a fifth piston phase error control module;
The fourth piston phase error control module is arranged between the third amplifier and the third phase modulator, and adjusts third piston phase errors of the third phase controller to different third composite beams according to the third amplified signals in the third amplifier;
the third piston phase error control module is arranged between the fourth amplifier and the second phase modulator, and adjusts second piston phase errors of the third phase controller to different third composite beams according to the fourth amplified signal in the fourth amplifier.
Specifically, the fourth piston phase error control module 1115' and the fifth piston phase error control module 1116' are respectively connected to the third amplifier 117' and the fourth amplifier 118', and adjust the third piston phase error between the second phase controller 111' and the different third combined light beams according to the third amplified signal and the fourth amplified signal.
The multi-aperture coherent synthesis laser communication method based on the circular polarization keying modulation can realize high-efficiency stable communication under the complex atmospheric condition, and optimize the performance of the FSOC system under the complex atmospheric condition, particularly under the strong atmospheric turbulence environment. The invention adopts CPolSK modulation technology and multi-aperture coherent synthesis technology, and realizes signal light CPolSK modulation, multi-aperture coherent synthesis receiving and demodulation through the optical antenna component with specific design, thereby effectively improving the turbulence resistance of the FSOC system.
It should be noted that, the method of the embodiment of the present invention may be performed by a single device, for example, a computer or a server. The method of the embodiment can also be applied to a distributed scene, and is completed by mutually matching a plurality of devices. In the case of such a distributed scenario, one of the devices may perform only one or more steps of the method of an embodiment of the present invention, the devices interacting with each other to accomplish the method.
It should be noted that the foregoing describes some embodiments of the present invention. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments described above and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.
Based on the same inventive concept, the invention also provides a multi-aperture coherent combination laser communication system based on circular offset keying modulation, which corresponds to the method of any embodiment.
Referring to fig. 7, the multi-aperture coherent combining laser communication system based on circular shift keying modulation comprises an FSOC transmitter 10 and a multi-aperture space diversity receiver 11;
the FSOC transmitter 10 generates FSOC signal light, modulates CPolSK the FSOC signal light to obtain emission light, and sends the emission light to the multi-aperture space diversity receiver 11;
The multi-aperture space diversity receiver 11 receives the emitted light, adaptively couples and coherently synthesizes the emitted light to obtain multi-aperture coherent synthesis laser, and demodulates and outputs the multi-aperture coherent synthesis laser.
For convenience of description, the above devices are described as being functionally divided into various modules, respectively. Of course, the functions of each module may be implemented in the same piece or pieces of software and/or hardware when implementing the present invention.
The device of the above embodiment is used for implementing the corresponding multi-aperture coherent synthesis laser communication method based on circular offset keying modulation in any of the foregoing embodiments, and has the beneficial effects of the corresponding method embodiments, which are not described herein.
It will be appreciated by persons skilled in the art that the foregoing discussion of any embodiment is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples, that combinations of technical features in the foregoing embodiments or in different embodiments may be implemented in any order and that many other variations of the different aspects of the embodiments described above exist within the spirit of the invention, which are not provided in detail for clarity.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and further implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.
Additionally, well-known power/ground connections to Integrated Circuit (IC) chips and other components may or may not be shown within the provided figures, in order to simplify the illustration and discussion, and so as not to obscure the embodiments of the present invention. Furthermore, the devices may be shown in block diagram form in order to avoid obscuring the embodiments of the present invention, and also in view of the fact that specifics with respect to implementation of such block diagram devices are highly dependent upon the platform within which the embodiments of the present invention are to be implemented (i.e., such specifics should be well within purview of one skilled in the art). Where specific details (e.g., circuits) are set forth in order to describe example embodiments of the invention, it should be apparent to one skilled in the art that embodiments of the invention can be practiced without, or with variation of, these specific details. Accordingly, the description is to be regarded as illustrative in nature and not as restrictive.
While the invention has been described in conjunction with specific embodiments thereof, many alternatives, modifications, and variations of those embodiments will be apparent to those skilled in the art in light of the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may use the embodiments discussed.
The present embodiments are intended to embrace all such alternatives, modifications and variances which fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, and the like, which are within the spirit and principles of the embodiments of the invention, are intended to be included within the scope of the invention.
Claims (8)
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| CN101645739A (en) * | 2009-09-14 | 2010-02-10 | 武汉邮电科学研究院 | Polarization demultiplexing device, polarization multiplexing light communication system and implementation method |
| CN115567115A (en) * | 2022-08-16 | 2023-01-03 | 北京遥测技术研究所 | An optical phased array laser communication system based on multi-aperture coherent combining |
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| US10116410B2 (en) * | 2014-09-19 | 2018-10-30 | Telefonaktiebolaget Lm Ericsson (Publ) | Optical transmitters and receivers using polarization multiplexing |
| CN114826399B (en) * | 2022-05-03 | 2023-09-12 | 浙江大学湖州研究院 | Circular polarization shift keying optical communication system based on partially coherent light |
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| CN101645739A (en) * | 2009-09-14 | 2010-02-10 | 武汉邮电科学研究院 | Polarization demultiplexing device, polarization multiplexing light communication system and implementation method |
| CN115567115A (en) * | 2022-08-16 | 2023-01-03 | 北京遥测技术研究所 | An optical phased array laser communication system based on multi-aperture coherent combining |
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