An apparatus and method for reverse modulation full duplex communication based on phase and amplitude modulation

Abstract

The application discloses a kind of based on phase and amplitude modulation reverse modulation full duplex communication device and method, belong to wireless optical communication technical field, the device includes: inquiry end: the signal input end of amplitude modulation module is connected the signal output end of laser shunt module, the signal input end of first propagation module is connected the signal output end of amplitude modulation module, the signal input end of phase demodulation module is connected the signal output end of laser shunt module and first propagation module;Reverse modulation end: second propagation module and signal light beam splitter module optical communication connection, signal light beam splitter module and phase modulation module optical communication connection, the signal input end of amplitude demodulation module is connected the signal output end of signal light beam splitter module;First propagation module and second propagation module optical communication connection, by the same beam optical signal is modulated and amplitude modulation is completed full duplex communication, better reverse modulation full duplex communication is realized.

Description

Technical Field

[0001] This invention belongs to the field of wireless optical communication technology, and particularly relates to a reverse modulation full-duplex communication device and method based on phase and amplitude modulation. Background Technology

[0002] Free-space optical communication is a wireless optical communication technology that uses lasers as a carrier. It has advantages such as low cost, large capacity, good security, fast network deployment, and no need to occupy spectrum resources. Free-space optical communication systems generally require the optical transmitter and optical receiver to be aligned and equipped with a PAT (Pointing, Acquisition and Tracking) system to achieve point-to-point communication. However, such systems are costly, bulky, and heavy.

[0003] The reverse modulation wireless optical communication system places the transmitter and receiver at the interrogation end, and the other end is a reverse modulation end consisting of a reflector and a modulator. The working principle is as follows: the interrogation end emits an unmodulated light beam to the reverse modulation end, which modulates the beam and returns it in the original direction. The interrogation end then demodulates the returned beam, thus achieving one-way free-space optical communication. This system does not require an automatic tracking system, significantly reducing the size and weight of one end. It can be widely used in small platforms such as small satellites, UAV reconnaissance, and ocean exploration.

[0004] Reverse modulation full-duplex communication, as a special form of reverse modulation wireless optical communication, can solve the problem that reverse modulation can only achieve unidirectional communication. The earliest research on reverse modulation full-duplex communication was in 2004 when a Mexican scholar used circular polarization keying (CPK) encoding to achieve single-wavelength, single-beam reverse modulation full-duplex communication. Also in 2004, Shay Thomas M. et al. studied a reverse modulation MRR FSO (Modulating Retro-Reflector Based Free Space Optical) system. In 2015, Zhang Peng et al. proposed using dual-wavelength laser emission to realize a full-duplex reverse modulation recovery space optical communication structure, and based on this structure, simulated and analyzed the intensity modulation demodulation mode of a ground station to a near-Earth small satellite full-duplex communication link with a communication distance of 300km and a communication rate of 1GHz. In the same year, Qiu Hao et al. proposed a single-source full-duplex MRR FSO scheme, in which the uplink uses on-off keying (OOK) modulation and the downlink uses amplitude modulation. In 2017, Chen Jing et al. proposed a reverse modulation system based on phase shift keying (PSK) / on-off keying (OOK) using a lithium niobate phase modulator and piezoelectric ceramics, capable of full-duplex operation, and verified its feasibility through simulation experiments. In 2018, Zhang Huan proposed a full-duplex communication channel model based on indoor visible light and experimentally achieved stable full-duplex communication at a distance of 3m with a downlink rate of 5 Mbit / s and an uplink rate of 2 Kbit / s. In 2018, Ke Xizheng et al., and in 2019, Yang Yufeng et al., both studied full-duplex communication systems based on a single indoor visible light source, realizing the dual functions of illumination and communication with visible light. Experiments demonstrated that the uplink and downlink communication of the system did not interfere with each other, and the communication effect was good. In 2019, Yin Xiaoli et al. proposed a full-duplex free-space optical communication system based on OAM (Orbital Angular Momentum) reverse modulation, which can perform high-order modulation and improve the system's bandwidth utilization.

[0005] International research on full-duplex MRR FSO communication links is limited. Domestic research mainly focuses on indoor visible light experiments, which has certain experimental limitations. Experiments using dual wavelengths to achieve full-duplex MRR suffer from inconsistent focusing points of the same lens for different wavelengths, placing high demands on equipment. While OAM-based full-duplex implementation can achieve high-order modulation of any OAM mode, OAM beams are sensitive and easily damaged, prone to wavefront distortion. Given the current state of MRR FSO research both domestically and internationally, further research is needed to address the simplex communication limitations of inverse modulation space optical communication systems. Summary of the Invention

[0006] The present invention aims to overcome the shortcomings of the prior art and provide a reverse modulation full-duplex communication device and method based on phase and amplitude modulation. Amplitude modulation and phase modulation are performed at the interrogation end and the reverse modulation end, respectively, to realize reverse modulation full-duplex communication, and further solve the problem of simplex communication limitation in reverse modulation space optical communication system.

[0007] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0008] In a first aspect, the present invention provides a reverse modulation full-duplex communication device based on phase and amplitude modulation, comprising an interrogation end and a reverse modulation end;

[0009] The interrogation terminal includes: a laser splitting module, an amplitude modulation module, a phase demodulation module, and a first propagation module;

[0010] The signal input terminals of the amplitude modulation module and the phase demodulation module are respectively connected to the signal output terminal of the laser splitter module, the signal input terminal of the first propagation module is connected to the signal output terminal of the amplitude modulation module, and the signal input terminal of the phase demodulation module is also connected to the signal output terminal of the first propagation module.

[0011] The reverse modulation end includes: a second propagation module, a signal light beam splitting module, a phase modulation module, and an amplitude demodulation module;

[0012] The second propagation module is optically connected to the signal light beam splitter module, the signal light beam splitter module is optically connected to the phase modulation module, and the signal input terminal of the amplitude demodulation module is connected to the signal output terminal of the signal light beam splitter module.

[0013] The first propagation module and the second propagation module are optically connected.

[0014] Optionally, the first propagation module includes an optical fiber circulator and an optical antenna.

[0015] The second propagation module includes optical antenna two;

[0016] The signal transmission end of the optical antenna is connected to the signal transmission end of the fiber optic circulator.

[0017] The fiber optic circulator is used to send the signal light from the amplitude modulation module to optical antenna one and to send the signal light from optical antenna two to the phase demodulation module.

[0018] The emission angles of optical antenna one and optical antenna two correspond.

[0019] Optionally, the laser splitter module includes a laser and an optical fiber splitter;

[0020] The signal input end of the fiber optic splitter is connected to the signal output end of the laser, and the signal output end is connected to the amplitude modulation module and the phase demodulation module respectively.

[0021] The signal beam splitting module includes a beam splitter, which is positioned on the side of optical antenna two that is away from optical antenna one.

[0022] Optionally, the amplitude modulation module includes: an acousto-optic modulator, a first driver, and an optical fiber amplifier;

[0023] The signal input terminal of the acousto-optic modulator is connected to the signal output terminal of the optical fiber splitter and the first driver, respectively, and the signal output terminal is connected to the signal input terminal of the optical fiber amplifier.

[0024] The first driver receives a first modulation signal at its signal input terminal;

[0025] The amplitude demodulation module includes: a first erbium-doped fiber amplifier and a first photodetector;

[0026] The first erbium-doped fiber amplifier is positioned in the direction of one signal beam of the beam splitter;

[0027] The signal input terminal of the first erbium-doped fiber amplifier is connected to the signal output terminal of the beam splitter, and the signal output terminal is connected to the signal input terminal of the first photodetector.

[0028] The first photodetector outputs a first modulation signal at its signal output terminal.

[0029] Optionally, the phase modulation module includes: a focusing lens, a piezoelectric ceramic, and a second driver;

[0030] The focusing lens and the second optical antenna are respectively disposed on both sides of the beam splitter, and the piezoelectric ceramic is disposed at the focal point of the focusing lens on the side away from the beam splitter.

[0031] The signal input terminal of the focusing lens is connected to the signal output terminal of the beam splitter and the piezoelectric ceramic, respectively.

[0032] The signal input terminal of the piezoelectric ceramic is connected to the signal output terminal of the focusing lens and the second driver, respectively, and the signal output terminal is connected to the signal input terminal of the focusing lens.

[0033] The second driver receives a second modulation signal at its signal input terminal;

[0034] The phase demodulation module includes: a second erbium-doped fiber amplifier, a polarization controller, an optical coupler, a second photodetector, and a signal processing unit;

[0035] The signal input terminal of the second erbium-doped fiber amplifier is connected to the signal output terminal of the fiber optic circulator, and the signal output terminal is connected to the signal input terminal of the optical coupler.

[0036] The signal output terminal of the polarization controller is connected to the signal input terminal of the optical coupler, and the signal input terminal is connected to the signal output terminal of the fiber optic splitter.

[0037] The signal input terminal of the second photodetector is connected to the signal output terminal of the optocoupler, and the signal output terminal is connected to the signal input terminal of the signal processing unit.

[0038] The signal output terminal of the signal processing unit outputs a second modulation signal.

[0039] In a second aspect, the present invention provides a reverse modulation full-duplex communication method based on phase and amplitude modulation, employing the reverse modulation full-duplex communication device based on phase and amplitude modulation described in any step of the first aspect, comprising:

[0040] In simplex communication from the interrogating end to the inverse modulation end:

[0041] On the inquiry end,

[0042] The first and second beams are obtained through the laser splitter module;

[0043] The amplitude modulation module modulates the first beam according to the first modulation signal, and the amplitude-modulated signal light is transmitted to the second propagation module of the reverse modulation end through the first propagation module.

[0044] At the inverse modulation end

[0045] The amplitude-modulated signal light is split into two beams by the signal light beam splitting module to obtain the first beam and the second beam.

[0046] The first signal light is photoelectrically detected by the amplitude demodulation module to obtain the recovered first modulation signal.

[0047] In simplex communication from the inverse modulation end to the interrogation end:

[0048] At the inverse modulation end

[0049] The phase modulation module modulates the second beam of signal light according to the second modulation signal, and the phase-amplitude modulated signal light is reflected back to the first propagation module of the interrogation end by the second propagation module.

[0050] On the inquiry end,

[0051] The phase demodulation module performs phase demodulation on the phase-amplitude modulated signal light according to the second beam to obtain the recovered second modulated signal.

[0052] Optionally, the step of amplitude modulation of the first beam according to the first modulation signal by the amplitude modulation module includes:

[0053] The first driver drives the acousto-optic modulator to perform amplitude modulation on the first beam according to the magnitude of the first modulation signal, and the intensity of the photoelectric field after amplitude modulation is... The expression is as follows:

[0054] ,

[0055] in, Let be the phase constant of the amplitude-modulated light. The frequency of the amplitude-modulated light. Let be the amplitude constant of the amplitude-modulated light. This is the first modulation signal.

[0056] Optionally, the step of performing photoelectric detection on the first beam of signal light through the amplitude demodulation module to obtain the recovered first modulation signal includes:

[0057] The first signal light is amplified by the first erbium-doped fiber amplifier and emitted into the first photodetector;

[0058] The first signal light is photoelectrically detected by the first photodetector, and the expression for the output photocurrent is as follows:

[0059] ,

[0060] in, The photocurrent output by the first photodetector. The photodetector responsivity is expressed in amperes (A / W). It is a constant;

[0061] The first modulation signal is output based on the output photocurrent.

[0062] Optionally, the step of phase modulating the second beam of signal light according to the second modulation signal via the phase modulation module includes:

[0063] The second driver drives the piezoelectric ceramic to vibrate according to the magnitude of the second modulation signal, thereby performing phase modulation on the second signal light. The photoelectric field intensity after phase-amplitude modulation is... The expression is as follows:

[0064] ,

[0065] in, This is the second modulation signal.

[0066] Optionally, the step of using a phase demodulation module to perform phase demodulation on the phase-amplitude modulated signal light according to the second beam to obtain the recovered second modulated signal includes:

[0067] The incident phase-amplitude modulated signal light is amplified by the second erbium-doped fiber amplifier and then transmitted to the optical coupler.

[0068] The polarization state of the incident second beam is adjusted by the polarization controller to match that of the phase-amplitude modulated signal light. The adjusted laser beam is then emitted into the optical coupler. The photoelectric field intensity of the polarization-adjusted second beam is... The expression is as follows;

[0069] ,

[0070] in, The phase constant of the second beam after polarization state adjustment. The frequency of the second beam after polarization state adjustment. The amplitude constant of the second beam after polarization state adjustment;

[0071] The amplified phase-amplitude modulated signal light and the polarization-adjusted second beam are coupled through the optical coupler, and the coupled signal light is emitted into the second photodetector. The power of the coupled signal light is... The expression is as follows:

[0072] ,

[0073] in, It is a constant. The signal optical power after phase-amplitude modulation. This represents the power of the second beam after polarization state adjustment.

[0074] The coupled signal light is coherently detected by the second photodetector, and the resulting photocurrent is sent to the signal processing unit. The expression for the output photocurrent is as follows:

[0075] ,

[0076] in, The photocurrent output by the second photodetector. The photodetector responsivity is expressed in A / W.

[0077] The signal processing unit outputs the second modulation signal based on the photocurrent, and the calculation formula is as follows:

[0078] .

[0079] Compared with existing technologies, the beneficial effects achieved by this invention are as follows: By setting an amplitude modulation module and a phase demodulation module at the interrogation end, and a phase modulation module and an amplitude demodulation module at the inverse modulation end, full-duplex communication is completed at both the interrogation end and the inverse modulation end using the same signal light. This eliminates the need for high requirements on lens devices and the need to consider the sensitivity and susceptibility of OAM beams, achieving inverse modulation full-duplex communication with fewer restrictions and better performance. The beam emitted by the laser is modulated at the interrogation end by an acousto-optic modulator. After reaching the inverse modulation end through the atmospheric channel, the phase of the optical signal is modulated by controlling the vibration of the piezoelectric ceramic. Simultaneously, by directly detecting the amplitude change of the demodulated signal, the reflected optical signal reaches the interrogation end and is demodulated by a coherent detection and signal processing unit. The inverse modulation full-duplex communication is completed by the propagation of a single signal light between the devices, solving the problem of simplex communication limitations in inverse modulation space optical communication systems. Attached Figure Description

[0080] Figure 1 The diagram shown is a schematic representation of a reverse modulation full-duplex communication device based on phase and amplitude modulation in one embodiment of the present invention.

[0081] Figure 2 The diagram shows a flowchart of a reverse modulation full-duplex communication method based on phase and amplitude modulation in one embodiment of the present invention.

[0082] Figure 1 In the middle: 1. Laser; 2. Fiber optic splitter; 3. Acousto-optic modulator; 4. First driver; 5. Fiber optic amplifier; 6. Fiber optic circulator; 7. Beam splitter; 8. Focusing lens; 9. Piezoelectric ceramic; 10. Second driver; 11. First erbium-doped fiber amplifier; 12. First photodetector; 13. Second erbium-doped fiber amplifier; 14. Polarization controller; 15. Optical coupler; 16. Second photodetector; 17. Signal processing unit. Detailed Implementation

[0083] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0084] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0085] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of these terms in this invention based on the specific circumstances.

[0086] Example 1

[0087] This embodiment provides a reverse modulation full-duplex communication device based on phase and amplitude modulation, including an interrogation end and a reverse modulation end;

[0088] The interrogation terminal includes: a laser splitting module for generating multiple lasers to be communicated; an amplitude modulation module for amplitude modulation of one of the split lasers; a phase demodulation module for phase demodulating the phase-amplitude modulated signal light reflected from the inverse modulation terminal based on the other split laser; and a first propagation module for transmitting the amplitude modulated signal light to the inverse modulation terminal and receiving the phase-amplitude modulated signal light reflected back from the inverse modulation terminal.

[0089] The signal input terminals of the amplitude modulation module and the phase demodulation module are respectively optically connected to the signal output terminal of the laser splitter module. The signal input terminal of the first propagation module is optically connected to the signal output terminal of the amplitude modulation module. The signal input terminal of the phase demodulation module is also optically connected to the signal output terminal of the first propagation module.

[0090] The reverse modulation end includes: a second propagation module for receiving amplitude-modulated signal light emitted by the interrogation end and reflecting phase-amplitude modulated signal light to the interrogation end; a signal light beam splitting module for splitting the amplitude-modulated signal light; a phase modulation module for phase modulation of the amplitude-modulated signal light; and an amplitude demodulation module for amplitude demodulation of the amplitude-modulated signal light.

[0091] The signal transmission ends of the second propagation module and the signal beam splitter module are connected by bidirectional optical communication through an atmospheric channel. The signal transmission ends of the signal beam splitter module and the phase modulation module are connected by bidirectional optical communication through an atmospheric channel. The signal input end of the amplitude demodulation module and the signal output end of the signal beam splitter module are connected by unidirectional optical communication through an atmospheric channel.

[0092] The signal transmission ends of the first propagation module and the second propagation module are connected by bidirectional optical communication through an atmospheric channel.

[0093] Full-duplex communication was achieved by performing phase modulation and amplitude modulation of the same optical signal at the interrogation end and the inverse modulation end, respectively, thus realizing better inverse modulation full-duplex communication.

[0094] Example 2

[0095] Based on Example 1, this example also incorporates the following design.

[0096] The interrogation end is used to split the laser beam to be communicated, generate an amplitude-modulated signal light from one of the laser beams and send it to the inverse modulation end, and perform phase demodulation on the amplitude-phase modulated signal light reflected back from the inverse modulation end based on the other laser beam. For example... Figure 1 As shown, in the interrogation terminal, the laser splitting module includes a laser 1 and an optical fiber splitter 2; the amplitude modulation module includes an acousto-optic modulator 3, a first driver 4, and an optical fiber amplifier 5; the first propagation module includes an optical fiber circulator 6 and an optical antenna 1; the phase demodulation module includes a second erbium-doped optical fiber amplifier 13, a polarization controller 14, an optical coupler 15, a second photodetector 16, and a signal processing unit 17.

[0097] The inverse modulation end is used to split the amplitude-modulated signal light emitted from the interrogation end, perform amplitude demodulation on one of the amplitude-modulated signal lights, and generate phase-amplitude modulated signal light based on the other amplitude-modulated signal light, which is then reflected back to the interrogation end. For example... Figure 1As shown, in the reverse modulation end, the second propagation module includes an optical antenna 2, the signal light beam splitting module includes a beam splitter 7, the amplitude demodulation module includes a first erbium-doped fiber amplifier 11 and a first photodetector 12, and the phase modulation module includes a focusing lens 8, a piezoelectric ceramic 9 and a second driver 10.

[0098] The fiber optic splitter 2 is used to split the laser beam to be communicated generated by the laser 1, and transmit the split laser beams to the acousto-optic modulator 3 and the polarization controller 14 respectively. The acousto-optic modulator 3 is used to modulate the amplitude of the incident laser beam. The first driver 4 is used to drive the acousto-optic modulator 3 to modulate the amplitude of the incident light according to the magnitude of the first modulation signal. The fiber optic amplifier 5 is used to amplify the amplitude-modulated signal light and transmit it to the optical antenna 1 through the fiber optic circulator 6. The optical antenna 1 and the optical antenna 2 propagate the optical signal through an atmospheric channel. The incident laser beam of the acousto-optic modulator 3 comes from the fiber optic splitter 2.

[0099] With the direction in which the amplitude-modulated signal light is incident on the second optical antenna as the front, the beam splitter 7 is tilted and placed behind the second optical antenna to split the amplitude-modulated signal light emitted from the second optical antenna into two beams. One beam enters the first erbium-doped fiber amplifier 11, and the other beam enters the focusing lens 8. The first erbium-doped fiber amplifier 11 and the first photodetector 12 are both located in one signal light transmission direction of the beam splitter 7. The first erbium-doped fiber amplifier 11 amplifies the incident amplitude-modulated signal light and transmits it to the first photodetector 12. The first photodetector 12 performs photoelectric detection on the amplitude-modulated signal light to obtain the amplitude information of the signal light. The incident signal light of the first erbium-doped fiber amplifier 11 comes from the beam splitter 7.

[0100] The focusing lens 8 and the second optical antenna are respectively disposed on both sides of the beam splitter 7, and the piezoelectric ceramic 9 is disposed at the focal point behind the focusing lens 8. The focusing lens 8 is used to converge the incident amplitude-modulated signal light onto the piezoelectric ceramic 9 and to output the phase-amplitude modulated signal light. The piezoelectric ceramic 9 is used to generate a phase shift to modulate the phase of the signal light. The second driver 10 is used to drive the piezoelectric ceramic 9 to vibrate according to the magnitude of the first modulation signal. The incident signal light of the focusing lens 8 comes from the beam splitter 7, and the output signal light comes from the piezoelectric ceramic 9.

[0101] The second erbium-doped fiber amplifier 13 amplifies the incident phase-amplitude modulated signal light and transmits it to the optical coupler 15; the polarization controller 14 adjusts the polarization state of the incident laser beam to match the phase-amplitude modulated signal light, and transmits the adjusted laser beam to the optical coupler 15; the optical coupler 15 couples the amplified phase-amplitude modulated signal light and the polarization-adjusted laser beam, and transmits the coupled signal light to the second photodetector 16. The second photodetector 16 performs coherent detection on the coupled signal light and sends the coherent detection result to the signal processing unit 17. The signal processing unit 17 outputs phase information. The incident signal light of the second erbium-doped fiber amplifier 13 comes from the first optical antenna, and the incident laser beam of the polarization controller 14 comes from the fiber splitter 2.

[0102] Example 3

[0103] like Figure 2 As shown, this embodiment provides a reverse modulation full-duplex communication method based on phase and amplitude modulation, and the specific steps are as follows:

[0104] At the interrogation end, the laser generated by laser 1 is split into two by fiber optic splitter 2. One path enters acousto-optic modulator 3 for amplitude modulation at the interrogation end according to the first modulation signal, and then is transmitted through fiber optic circulator 6 and optical antenna 1, and transmitted in the atmospheric channel. The other path is transmitted to polarization controller 14. The unmodulated photoelectric field intensity at the interrogation end... for:

[0105] ,

[0106] In the formula, The phase constant, For the frequency of light, is the amplitude constant.

[0107] The first driver 4 operates according to the first modulation signal. The magnitude of the acousto-optic modulator 3 modulates the amplitude of the incident light signal, thus the intensity of the photoelectric field after amplitude modulation. for:

[0108] .

[0109] The amplitude-modulated optical signal at the interrogation end is amplified by the fiber amplifier 5, output by the fiber optic circulator 6 to the optical antenna 1, and transmitted in the atmospheric channel.

[0110] The light beam sent from the interrogation end is received by the optical antenna 2 at the inverse modulation end, and split into two at the beam splitter 7. One beam reaches the focusing lens 8; the other beam goes to the first erbium-doped fiber amplifier 11 for optical signal amplification. The amplified optical signal enters the first photodetector 12 for direct detection. The first photodetector 12, which performs direct detection, responds to changes in the optical signal power, and can only respond to changes in the optical signal power, generating a first photocurrent. Corresponding demodulation Signal:

[0111] ,

[0112] in, Photodetector responsivity, measured in A / W. It is a constant; for The light wave is emitted, and the photodetector outputs the amplitude value. Since this frequency cannot be clearly observed in the first photodetector 12, the high-frequency optical term is neglected. Therefore, the above formula can be written as:

[0113] ,

[0114] This is how the signal can be obtained. The output of .

[0115] The piezoelectric ceramic 9 is positioned at the focal point of the focusing lens 8. The light signal, modulated initially, passes through an atmospheric channel and is focused onto the piezoelectric ceramic 9 by the focusing lens 8. Driven by the second driver 10, the piezoelectric ceramic 9 moves in sync with the applied signal. The magnitude of the vibration causes the light to vibrate back and forth, resulting in a phase shift, which in turn modulates the phase of the optical signal.

[0116] The amplitude-phase modulated photoelectric field intensity obtained by the second modulation of piezoelectric ceramic 9 for:

[0117] ,

[0118] Thus, the signal The phase of the light was loaded, and the laser underwent phase modulation at the inverse modulation end.

[0119] Due to the "cat's eye" effect, the light beam emitted from the interrogating end is reflected by the reverse modulation end and returns to the interrogating end in the original direction. After passing through the optical antenna 1 and the fiber optic circulator 6 at the interrogating end, it enters the second erbium-doped fiber amplifier 13 from the fiber input end face to amplify the optical signal. Then, it is output into the optical coupler 15. At the same time, the local oscillator light that has passed through the fiber optic splitter 2 and the polarization controller 14 also enters the optical coupler 15. The polarization controller 14 adjusts the polarization state of the local oscillator light.

[0120] Photoelectric field strength of local oscillator It can be written as:

[0121] ,

[0122] In the formula, Let be the phase constant of the local oscillator light. The frequency of the local oscillator light. is the amplitude constant of the local oscillator light.

[0123] After passing through polarization controller 14, assuming the signal light and local oscillator light have the same polarization direction, according to the theory of coherent detection, the light signal intensity projected onto the second photodetector 16 after passing through optical coupler 15 is: The detected optical power is , It is a constant. The power of the light after amplitude-phase modulation. This represents the power of the local oscillator.

[0124] ,

[0125] generally The photocurrent generated by the second photodetector 16 for coherent detection is:

[0126] ,

[0127] Omit the DC term:

[0128] ,

[0129] After processing by the signal processing unit 17, have to:

[0130] ,

[0131] in, , , , Since these are all constants, we eliminate them and then perform an inverse cosine operation to obtain the signal. The output of .

[0132] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media containing computer-usable program code, including but not limited to disk storage, CD-ROM, optical storage, etc.

[0133] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus systems, and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0134] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0135] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0136] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A reverse modulation full-duplex communication device based on phase and amplitude modulation, characterized in that, Includes the interrogation end and the inverse modulation end; The interrogation terminal includes: a laser splitting module, an amplitude modulation module, a phase demodulation module, and a first propagation module; The signal input terminals of the amplitude modulation module and the phase demodulation module are respectively connected to the signal output terminal of the laser splitter module, the signal input terminal of the first propagation module is connected to the signal output terminal of the amplitude modulation module, and the signal input terminal of the phase demodulation module is also connected to the signal output terminal of the first propagation module. The reverse modulation end includes: a second propagation module, a signal light beam splitting module, a phase modulation module, and an amplitude demodulation module; The second propagation module is optically connected to the signal light beam splitter module, the signal light beam splitter module is optically connected to the phase modulation module, and the signal input terminal of the amplitude demodulation module is connected to the signal output terminal of the signal light beam splitter module. The first propagation module and the second propagation module are optically connected; The first propagation module includes an optical fiber circulator and an optical antenna. The second propagation module includes optical antenna two; The signal transmission end of the optical antenna is connected to the signal transmission end of the fiber optic circulator. The fiber optic circulator is used to send the signal light from the amplitude modulation module to optical antenna one and to send the signal light from optical antenna two to the phase demodulation module. The emission angles of optical antenna one and optical antenna two correspond; The laser splitter module includes a laser and an optical fiber splitter; The signal input end of the fiber optic splitter is connected to the signal output end of the laser, and the signal output end is connected to the amplitude modulation module and the phase demodulation module respectively. The signal beam splitting module includes a beam splitter, which is positioned on the side of optical antenna two that is away from optical antenna one.

2. The inverse modulation full-duplex communication device based on phase and amplitude modulation according to claim 1, characterized in that, The amplitude modulation module includes: an acousto-optic modulator, a first driver, and an optical fiber amplifier; The signal input terminal of the acousto-optic modulator is connected to the signal output terminal of the optical fiber splitter and the first driver, respectively, and the signal output terminal is connected to the signal input terminal of the optical fiber amplifier. The first driver receives a first modulation signal at its signal input terminal; The amplitude demodulation module includes: a first erbium-doped fiber amplifier and a first photodetector; The first erbium-doped fiber amplifier is positioned in the direction of one signal beam of the beam splitter; The signal input terminal of the first erbium-doped fiber amplifier is connected to the signal output terminal of the beam splitter, and the signal output terminal is connected to the signal input terminal of the first photodetector. The first photodetector outputs a first modulation signal at its signal output terminal.

3. The inverse modulation full-duplex communication device based on phase and amplitude modulation according to claim 2, characterized in that, The phase modulation module includes: a focusing lens, a piezoelectric ceramic, and a second driver; The focusing lens and the second optical antenna are respectively disposed on both sides of the beam splitter, and the piezoelectric ceramic is disposed at the focal point of the focusing lens on the side away from the beam splitter. The signal input terminal of the focusing lens is connected to the signal output terminal of the beam splitter and the piezoelectric ceramic, respectively. The signal input terminal of the piezoelectric ceramic is connected to the signal output terminal of the focusing lens and the second driver, respectively, and the signal output terminal is connected to the signal input terminal of the focusing lens. The second driver receives a second modulation signal at its signal input terminal; The phase demodulation module includes: a second erbium-doped fiber amplifier, a polarization controller, an optical coupler, a second photodetector, and a signal processing unit; The signal input terminal of the second erbium-doped fiber amplifier is connected to the signal output terminal of the fiber optic circulator, and the signal output terminal is connected to the signal input terminal of the optical coupler. The signal output terminal of the polarization controller is connected to the signal input terminal of the optical coupler, and the signal input terminal is connected to the signal output terminal of the fiber optic splitter. The signal input terminal of the second photodetector is connected to the signal output terminal of the optocoupler, and the signal output terminal is connected to the signal input terminal of the signal processing unit. The signal output terminal of the signal processing unit outputs a second modulation signal.

4. A full-duplex communication method based on phase and amplitude modulation using inverse modulation, employing the full-duplex communication device based on phase and amplitude modulation as described in claim 3, characterized in that... include: In simplex communication from the interrogating end to the inverse modulation end: On the inquiry end, The first and second beams are obtained through the laser splitter module; The amplitude modulation module modulates the first beam according to the first modulation signal, and the amplitude-modulated signal light is transmitted to the second propagation module of the reverse modulation end through the first propagation module. At the inverse modulation end The amplitude-modulated signal light is split into two beams by a signal light beam splitting module to obtain the first beam and the second beam. The first signal light is photoelectrically detected by the amplitude demodulation module to obtain the recovered first modulation signal; In simplex communication from the inverse modulation end to the interrogation end: At the inverse modulation end The phase modulation module modulates the second beam of signal light according to the second modulation signal, and the phase-amplitude modulated signal light is reflected back to the first propagation module of the interrogation end by the second propagation module. On the inquiry end, The phase demodulation module performs phase demodulation on the phase-amplitude modulated signal light according to the second beam to obtain the recovered second modulated signal.

5. The inverse modulation full-duplex communication method based on phase and amplitude modulation according to claim 4, characterized in that, The step of amplitude modulation of the first beam according to the first modulation signal by the amplitude modulation module includes: The first driver drives the acousto-optic modulator to perform amplitude modulation on the first beam according to the magnitude of the first modulation signal, and the intensity of the photoelectric field after amplitude modulation is... The expression is as follows: ， in, Let be the phase constant of the amplitude-modulated light. The frequency of the amplitude-modulated light. Let be the amplitude constant of the amplitude-modulated light. This is the first modulation signal.

6. The inverse modulation full-duplex communication method based on phase and amplitude modulation according to claim 5, characterized in that, The step of performing photoelectric detection on the first beam of signal light through the amplitude demodulation module to obtain the recovered first modulated signal includes: The first signal light is amplified by the first erbium-doped fiber amplifier and emitted into the first photodetector; The first signal light is photoelectrically detected by the first photodetector, and the expression for the output photocurrent is as follows: ， in, The photocurrent output by the first photodetector. The photodetector responsivity is expressed in amperes (A / W). It is a constant; The first modulation signal is output based on the output photocurrent.

7. The inverse modulation full-duplex communication method based on phase and amplitude modulation according to claim 5, characterized in that, The step of performing phase modulation on the second beam of signal light according to the second modulation signal via the phase modulation module includes: The second driver drives the piezoelectric ceramic to vibrate according to the magnitude of the second modulation signal, thereby performing phase modulation on the second signal light. The photoelectric field intensity after phase-amplitude modulation is... The expression is as follows: ， in, This is the second modulation signal.

8. The inverse modulation full-duplex communication method based on phase and amplitude modulation according to claim 7, characterized in that, The step of using a phase demodulation module to demodulate the phase-amplitude modulated signal light according to the second beam to obtain the recovered second modulated signal includes: The incident phase-amplitude modulated signal light is amplified by the second erbium-doped fiber amplifier and then transmitted to the optical coupler. The polarization state of the incident second beam is adjusted by the polarization controller to match that of the phase-amplitude modulated signal light. The adjusted laser beam is then emitted into the optical coupler. The photoelectric field intensity of the polarization-adjusted second beam is... The expression is as follows; ， in, The phase constant of the second beam after polarization state adjustment. The frequency of the second beam after polarization state adjustment. The amplitude constant of the second beam after polarization state adjustment; The amplified phase-amplitude modulated signal light and the polarization-adjusted second beam are coupled through the optical coupler, and the coupled signal light is emitted into the second photodetector. The power of the coupled signal light is... The expression is as follows: ， in, It is a constant. The signal optical power after phase-amplitude modulation. This represents the power of the second beam after polarization state adjustment. The coupled signal light is coherently detected by the second photodetector, and the resulting photocurrent is sent to the signal processing unit. The expression for the output photocurrent is as follows: ， in, The photocurrent output by the second photodetector. The photodetector responsivity is expressed in A / W. The signal processing unit outputs the second modulation signal based on the photocurrent, and the calculation formula is as follows: 。

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