Multi-channel photon channelization receiver and method based on single optical comb and acousto-optic frequency shifting

Abstract

The present invention discloses a multi-channel photon channelization receiver and method based on a single optical comb and acousto-optic frequency shifting, including a laser, a Mach-Zehnder modulator MZM, a phase modulator, two acousto-optic modulators, an optical attenuator, two erbium-doped fiber amplifiers, a 1×2 optical splitter, a 1×3 optical splitter, a 1×18 optical splitter, three wavelength division multiplexers WDM, an optical bandpass filter, 18 optical orthogonal mixers, 36 balanced detectors, 18 electrical orthogonal couplers and multiple electrical bandpass filters; a single phase modulator is used to generate multi-comb lines and narrow-spaced OFC, and an acousto-optic modulator is combined to shift the frequency of the optical local oscillator signal, and finally, the instantaneous reception of multi-channel radio frequency signals is realized through optical coherent detection. The present invention has a simple structure and strong operability; it is very practical and can be applied to various systems that require large-bandwidth signal reception.

Description

Technical Field

[0001] The invention belongs to the field of microwaves, and in particular relates to a multi-channel photon channelized receiver. Background Art

[0002] With the increase in communication capacity and the number of services, modern electronic systems urgently need the ability to process broadband signals. Traditional RF receivers are limited by inherent electronic bottlenecks and have problems such as limited bandwidth, large transmission loss, large volume and weight, and weak anti-electromagnetic interference. Microwave photon channelization technology has the function of dividing broadband RF signals into narrowband channels compatible with current electronic devices, which can meet the reception requirements of ultra-wideband, multi-channel, and multi-function.

[0003] There are three main methods to achieve microwave photon channelization. The first method is to modulate the radio frequency (RF) signal into the optical domain and then use an optical filter array to split the spectrum into multiple channels. The second method is to copy the RF signal to the comb line of the optical frequency comb (OFC), filter it by a periodic optical filter, and then channelize it by a conventional optical demultiplexer, where the filtering period is slightly different from the comb line frequency interval. The third method is based on two coherent OFCs with slightly different comb line frequency intervals, one OFC is used to propagate the RF signal, and the other OFC is used to down-convert different components of the RF signal to the same intermediate frequency band of different channels. These two OFCs can also be equivalently generated by using linear frequency modulated optical pulses, where appropriate time delays can be introduced between the optical pulses to achieve slightly different OFC spacings. On the one hand, the above methods have high requirements on the quality factor and stability of the optical filter. On the other hand, the above methods require the two OFCs to have strong coherence, a large number of comb lines, and a large free spectral range, resulting in an engineering implementation bottleneck for the channelized reception of multi-channel RF signals. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the present invention provides a multi-channel photon channelized receiver based on a single optical comb and acousto-optic frequency shifting, including a laser, a Mach-Zehnder modulator MZM, a phase modulator, two acousto-optic modulators, an optical attenuator, two erbium-doped fiber amplifiers, a 1×2 optical splitter, a 1×3 optical splitter, a 1×18 optical splitter, three wavelength division multiplexers WDM, an optical bandpass filter, 18 optical orthogonal mixers, 36 balanced detectors, 18 electrical orthogonal couplers and multiple electrical bandpass filters; a single phase modulator is used to generate multi-comb lines and narrow-spaced OFC, and an acousto-optic modulator is combined to shift the frequency of the optical local oscillator signal, and finally, through optical coherent detection, instantaneous reception of multi-channel radio frequency signals is achieved. The present invention has a simple structure and strong operability; it is very practical and can be applied to various systems that require large-bandwidth signal reception.

[0005] The technical solution adopted by the present invention to solve the technical problem includes the following steps:

[0006] A multi-channel photon channelized receiver based on a single optical comb and acousto-optic frequency shifting, comprising a laser, a Mach-Zehnder modulator MZM, a phase modulator, two acousto-optic modulators, an optical attenuator, two erbium-doped fiber amplifiers, a 1×2 optical splitter, a 1×3 optical splitter, a 1×18 optical splitter, three wavelength division multiplexers WDM, an optical bandpass filter, 18 optical orthogonal mixers, 36 balanced detectors, 18 electrical orthogonal couplers and a plurality of electrical bandpass filters;

[0007] The output port of the laser is connected to a 1×2 optical splitter, output port 1 of the 1×2 optical splitter is connected to the optical input port of the MZM, and output port 2 of the 1×2 optical splitter is connected to the optical input port of the phase modulator;

[0008] The output port of the MZM is connected to the input port of the erbium-doped fiber amplifier 1, the output port of the erbium-doped fiber amplifier 1 is connected to the 1×18 splitter, and the output port of the 1×18 splitter is connected to the RF input ports of the optical orthogonal mixer 1 to the optical orthogonal mixer 18 respectively;

[0009] The output port of the phase modulator is connected to the input port of the erbium-doped fiber amplifier 2, the output port of the erbium-doped fiber amplifier 2 is connected to the optical bandpass filter, the output port of the optical bandpass filter is connected to the 1×3 optical splitter, and the three output ports of the 1×3 optical splitter are respectively connected to the input ports of the acousto-optic modulator 1, the optical attenuator and the acousto-optic modulator 2;

[0010] The output ports of the acousto-optic modulator 1, the optical attenuator and the acousto-optic modulator 2 are respectively connected to the input ports of three wavelength division multiplexers WDM1, WDM2 and WDM3; the six output ports of WDM1 are respectively connected to the input ports of the optical orthogonal mixer 1 to the optical orthogonal mixer 6, the six output ports of WDM2 are respectively connected to the input ports of the optical orthogonal mixer 7 to the optical orthogonal mixer 12, and the six output ports of WDM3 are respectively connected to the input ports of the optical orthogonal mixer 13 to the optical orthogonal mixer 18;

[0011] The four output ports of each optical orthogonal mixer are divided into two groups, and the two output ports in each group are respectively connected to the input ports of two balanced detectors; the output ports of every two balanced detectors are respectively connected to the two input ports of an electrical orthogonal coupler; each output port of the electrical orthogonal coupler obtains a channel of receiving signal after passing through an electrical bandpass filter.

[0012] A signal receiving method using a multi-channel photon channelized receiver based on a single optical comb and acousto-optic frequency shifting comprises the following steps:

[0013] Step 1: The laser generates a laser signal, which is output to the MZM and phase modulator respectively through a 1×2 optical splitter;

[0014] Step 2: MZM is powered by RF signal V RF (t) = V 0 cos(ω RF t) drive, where ω RF is the angular frequency of the RF signal, V 0 is the strength of the RF signal, then the output expression of MZM is:

[0015]

[0016] In the formula, E in (t) is the laser signal output by the laser, V π is the half-wave voltage of MZM, m=πV 0 / V π is the modulation index; and is the phase shift introduced by the DC bias on the upper and lower arms of the MZM, is the DC bias angle of MZM; φ is the phase difference of the RF signal loaded on the upper and lower arms of MZM; J n (·) is the nth-order Bessel function of the first kind. In the case of small signal modulation, the higher-order Bessel coefficients can be ignored. When only the first-order optical sideband is considered, equation (1) is simplified to:

[0017]

[0018] Set the half-wave voltage of MZM so that MZM works at the minimum point and performs suppressed carrier double-sideband modulation;

[0019] Step 3: Phase modulator is composed of two-tone signal V LO (t) = V 2 [cos(ω 1 t+△φ)+cos(ω 2 t)] driven, the output expression of the phase modulator is recorded as:

[0020]

[0021] Where V 2 Indicates the strength of the dual-tone signal, ω 1 ,ω 2 represents the angular frequency of the two signals, and ω 2 =2ω 1 , △φ 1 Indicates the phase difference between the two signals of the dual-tone signal, m 1 =m 2 =πV 2 / V π,PM , V π,PM is the half-wave voltage of the phase modulator.

[0022] Step 4: Set the frequencies of the two local oscillator signals input to the phase modulator to be f LO and 3f LO , the phase difference is 90°, and the modulation index is 1.5; after passing through the phase modulator, a center frequency of f is generated c , the frequency interval is f LO N-line optical comb;

[0023] Step 5: After being amplified by an erbium-doped fiber amplifier, the N-line optical comb is divided into three paths. Two of the paths use an acousto-optic modulator to shift the frequency of each optical comb, and then use WDM to filter out the frequency f k,n =nf LO +f c +k△f signal component, where n is an integer in the interval [-N / 2, N / 2], representing the sideband order of the optical comb line, △f = f LO / 6 represents the frequency shift of the acousto-optic modulator, k = -1, 0, 1 represents the sequence number of each path after the optical splitting, that is, the first path shifts down the frequency △f, the second path does not shift the frequency, and the third path shifts the frequency △f; the filtered frequency is f k,n The signal is connected to the LO port of the optical orthogonal mixer and beats with the RF signal. The signal after the beat is recorded as:

[0024]

[0025] Where R is the responsivity of the PD, Φ+ =2π(f RF +f c )t represents the phase of the RF signal, Φ k,n =2π(nf LO +f c +k△f)t represents the phase of the LO optical frequency comb signal after frequency shift, B n represents the amplitude of the nth LO optical frequency comb;

[0026] The output signals of the two balanced detectors are recorded as:

[0027]

[0028] Step 6: After balanced detection, only I and Q information are left in the two channels, and the second-order intermodulation distortion and DC terms are eliminated. However, since the signal is down-converted to the same intermediate frequency, spectrum aliasing will occur, that is, the intermediate frequency signals of different sub-channels are mirror images of each other. An electrical orthogonal coupler is used to separate the two mirror images of each other, and finally the required intermediate frequency signal is filtered out using an electrical bandpass filter of the same frequency; in this way, the phase modulator and the acousto-optic modulator are combined, and an LO optical comb is used, and then the acousto-optic modulator is used for frequency shifting to realize the reception of 6 channel signals; if N is an odd number, the generated optical comb contains (N-1) / 2 positive-order sidebands, which can realize the reception of up to 3(N-1) channels; if N is an even number, the generated optical comb contains N / 2 positive-order sidebands, which can realize the reception of up to 3N channels.

[0029] The beneficial effects of the present invention are as follows:

[0030] The present invention utilizes a phase modulator and an acousto-optic modulator to realize the reception of a wideband signal. By reasonably setting the amplitude and phase of the input signal, a microwave photon channelized receiver capable of receiving wideband signals can be finally obtained by using an N-th narrow-spaced optical comb. The present invention has a simple structure and strong operability; it is highly practical and can be applied to various systems requiring wideband signal reception. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a diagram of a multi-channel photon channelized receiver device based on a single optical comb and acousto-optic frequency shifting according to the present invention.

[0032] Figure 2 The embodiment of the present invention is based on f 1,1 Taking the comb line as an example, the spectrum diagram of the system during down-conversion process.

[0033] Figure 3 The figure is a schematic diagram of the spectrum of a large broadband signal during down-conversion according to an embodiment of the present invention.

[0034] Figure 4 This is a multi-line optical frequency comb spectrum diagram generated by the phase modulator according to an embodiment of the present invention.

[0035] Figure 5 FIG. 4 is a spectrum diagram of a signal after passing through an electrical bandpass filter according to an embodiment of the present invention.

[0036] Figure 6 This is a signal spectrum diagram without image suppression according to an embodiment of the present invention.

[0037] Figure 7 This is a signal spectrum diagram after image suppression by an electric orthogonal coupler according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0039] In order to overcome the shortcomings of the prior art and realize the effective reception of multi-channel RF signals, the present invention proposes a microwave photon channelized receiver based on a single optical comb and acousto-optic frequency shifting, which uses a single phase modulator to generate multi-comb lines and narrow-spaced OFC, combines an acousto-optic modulator to frequency shift the optical local oscillator signal (Local Oscillator, LO), and finally realizes instantaneous reception of multi-channel RF signals through optical coherent detection.

[0040] A multi-channel photon channelized receiver based on a single optical comb and acousto-optic frequency shifting includes a laser, a Mach-Zehnder Modulator (MZM), a phase modulator, two acousto-optic modulators, an optical attenuator, two erbium-doped fiber amplifiers, a 1×2 optical splitter, a 1×3 optical splitter, a 1×18 optical splitter, three wavelength division multiplexers (Wavelength Division Multiplexing, WDM), an optical bandpass filter, and 18 optical orthogonal mixers, balanced detectors, electrical orthogonal couplers, and electrical bandpass filters.

[0041] The output port of the laser is connected to a 1×2 optical splitter, output port 1 of the 1×2 optical splitter is connected to the optical input port of the MZM, and output port 2 is connected to the optical input port of the phase modulator; the output port of the MZM is connected to the input port of the erbium-doped fiber amplifier 1, the output port of the erbium-doped fiber amplifier 1 is connected to a 1×18 splitter, and the output ports of the 1×18 splitter are respectively connected to the RF input ports of optical orthogonal mixers 1–18; the output port of the phase modulator is connected to the input port of the erbium-doped fiber amplifier 2, the output port of the erbium-doped fiber amplifier 2 is connected to an optical bandpass filter, the output port of the optical bandpass filter is connected to a 1×3 optical splitter, and the three output ports of the 1×3 optical splitter are respectively connected to an acousto-optic modulator 1, an optical attenuator and The input port of the acousto-optic modulator 2; the output ports of the acousto-optic modulator 1, the optical attenuator and the acousto-optic modulator 2 are respectively connected to the input ports of WDM1, WDM2 and WDM3; the 6 output ports of WDM1 are respectively connected to the input ports of optical orthogonal mixers 1-6, the 6 output ports of WDM2 are connected to the input ports of optical orthogonal mixers 7-12, and the 6 output ports of WDM3 are connected to the input ports of optical orthogonal mixers 13-18; the four output ports of the optical orthogonal mixer are respectively connected to the input ports of two balanced detectors; the output ports of the two balanced detectors are respectively connected to the two input ports of the electrical orthogonal coupler; one output port of the electrical orthogonal coupler can obtain a receiving signal of one channel after passing through an electrical bandpass filter.

[0042] The MZM is powered by the RF signal V RF (t) = V 0 cos(ω RF t) drive, where ω RF is the angular frequency of the RF signal, V 0 is the strength of the RF signal, then the output expression of MZM is:

[0043]

[0044] In the formula, E in (t) is the laser signal output by the laser, V π is the half-wave voltage of MZM, m=πV 0 / V π is the modulation index; and is the phase shift introduced by the DC bias on the upper and lower arms of the MZM, is the DC bias angle of MZM; φ is the phase difference of the RF signal loaded on the upper and lower arms of MZM; J n (·) is the nth-order Bessel function of the first kind. In the case of small signal modulation, the higher-order Bessel coefficients can be ignored. When only the first-order optical sideband is considered, the above formula can be simplified to:

[0045]

[0046] Set the half-wave voltage of MZM so that MZM works at the minimum point and performs suppressed carrier double-sideband modulation.

[0047] The phase modulator is composed of a dual-tone signal V LO (t) = V 2 [cos(ω 1 t+△φ)+cos(ω 2 t)] driven, the output expression of the phase modulator is recorded as:

[0048]

[0049] Where V 2 Indicates the strength of the dual-tone signal, ω 1 ,ω 2 represents the angular frequency of the two signals, and ω 2 =2ω 1 , △φ 1 Indicates the phase difference between the two signals of the dual-tone signal, m 1 =m 2 =πV 2 / V π,PM , V π,PM is the half-wave voltage of the phase modulator.

[0050] Set the frequencies of the two local oscillator signals input to the phase modulator to be f LO and 3f LO , the phase difference is 90°, and the modulation index is 1.5. After passing through the phase modulator, a center frequency of f is generated. c , the frequency interval is f LO After being amplified by an erbium-doped fiber amplifier, it is divided into three paths. Each path uses an acousto-optic modulator to shift the frequency of each optical comb, and then uses WDM to filter out the frequency f k,n =nf LO +f c +k△f signal component, where n is an integer in the interval [-N / 2, N / 2], representing the sideband order of the optical comb line, △f = f LO / 6 represents the frequency shift of the AOM, k=-1,0,1 represents the sequence number of each path after the optical split, that is, the first path has a frequency shift of △f, the second path has no frequency shift, and the third path has a frequency shift of △f. The filtered frequency is f k,n The signal is connected to the LO port of the optical orthogonal mixer to beat with the RF signal. The signal after the beat is recorded as:

[0051]

[0052] Where R is the responsivity of the PD, Φ + =2π(fRF +f c )t represents the phase of the RF signal, Φ k,n =2π(nf LO +f c +k△f)t represents the phase of the LO optical frequency comb signal after frequency shift, B n Represents the amplitude of the nth LO optical frequency comb.

[0053] The output signals of the two balanced detectors are recorded as:

[0054]

[0055] After balanced detection, only I and Q information are left in the two channels, and the second-order intermodulation distortion and DC terms are eliminated. However, since the signal is down-converted to the same intermediate frequency, spectrum aliasing will occur, that is, the intermediate frequency signals of different sub-channels are mirror images of each other. An electrical orthogonal coupler can be used to separate the two mirror images of each other, and finally the required intermediate frequency signal is filtered out using an electrical bandpass filter of the same frequency. In this way, the phase modulator and the acousto-optic modulator are combined, an LO optical comb is used, and then the acousto-optic modulator is used for frequency shifting, so that the reception of 6 channel signals can be achieved. If N is an odd number, the optical comb generated by the above scheme contains (N-1) / 2 positive-order sidebands, which can achieve the reception of up to 3(N-1) channels; if N is an even number, the optical comb generated by the above scheme contains N / 2 positive-order sidebands, which can achieve the reception of up to 3N channels.

[0056] With f 1,1 、f 2,1 and f 3,1 Taking the comb line as an example, the down-conversion schematic diagram is as follows Figure 2 As shown in the figure, (a–h) correspond to the spectrum at each node in the figure. (a) represents the positive first-order optical sideband generated by the modulation of the broadband RF signal into the optical domain, which is divided into 6 channels numbered 1–6; (b) represents f 1,1 、f 2,1 and f 3,1 3 LO optical signals, where f 1,1 By 2,1 Shifting down the frequency by 1 GHz, we get, f 3,1 By 2,1 Shift the frequency up by 1 GHz to get f 1,1 Align RF signal spectrum components 1 and 4, i.e., channels 1 and 4, f 2,1 Align channel 2 and channel 5, f 3,1Alignment of channel 3 and channel 6; (c) (d) represent the intermediate frequency signals after the RF signal beats with the LO signal and then passes through balanced detector 1 and balanced detector 2 for down-conversion. Since the spectrum components of the RF signal aligned with the center frequency of the three LO signals are different, spectrum aliasing occurs in part of the intermediate frequency range after down-conversion, and when different image suppression mixers are down-converted to the same intermediate frequency range, the aliased spectrum components are also different; (e) and (f) represent the spectrum output from the two ports of the electrically orthogonal coupler, and the corresponding signals are output after image suppression, and the two outputs are mirror channels of each other; (g) and (h) represent the spectrum output from the RF signal with a frequency of f 1,1 After the LO signal beats the frequency and passes through the electrical orthogonal coupler and electrical bandpass filter, the frequency range is 1-2 GHz, that is, the spectrum diagram of channel 1 and channel 4. Similarly, when the LO signal is not frequency shifted, that is, the RF signal is at a frequency of f 2,1 The LO signal is beat frequency, and the electrical orthogonal coupler 7 can output channel 2 and channel 5 at the same time, and the two are mirror channels of each other; when the LO signal is frequency shifted, the frequency is f 3,1 When , the electrical orthogonal coupler 13 can simultaneously output channel 3 and channel 6, which are mirror images of each other. Similarly, for other frequency parts of the broadband RF signal, the corresponding f is configured by the phase modulator and the acousto-optic modulator. 1,2 ,f 2,2 ,f 3,2 、f 1,3 ,f 2,3 ,f 3,3 、f 1,4 ,f 2,4 ,f 3,4 and f 1,n ,f 2,n ,f 3,n The optical comb of the frequency can output the corresponding spectrum components, thereby realizing the reception of large broadband signals, such as Figure 3 shown. Specific embodiment:

[0058] The device of this embodiment includes a laser, an RF signal source, an LO signal source, a DC source, a spectrum analyzer, an MZM, a phase modulator, an acousto-optic modulator 1, an acousto-optic modulator 2, an optical attenuator, an erbium-doped fiber amplifier, a 1×2 optical splitter, a 1×3 optical splitter, a 1×18 optical splitter, WDM1-3, an optical bandpass filter, an optical orthogonal mixer 1-18, a balanced detector 1-36, an electrical orthogonal coupler 1-18, and an electrical bandpass filter.

[0059] 1. Device connection. The output port of the laser is connected to a 1×2 optical splitter, the output port 1 of the 1×2 optical splitter is connected to the optical input port of the MZM, and the output port 2 is connected to the optical input port of the phase modulator; the output port of the MZM is connected to the input port of the erbium-doped fiber amplifier 1, the output port of the erbium-doped fiber amplifier 1 is connected to a 1×18 splitter, and the output ports of the 1×18 splitter are respectively connected to the RF input ports of optical orthogonal mixers 1-18; the output port of the phase modulator is connected to the input port of the erbium-doped fiber amplifier 2, the output port of the erbium-doped fiber amplifier 2 is connected to an optical bandpass filter, the output port of the optical bandpass filter is connected to a 1×3 optical splitter, and the three output ports of the 1×3 optical splitter are respectively connected to the acousto-optic modulator 1, the optical attenuator The output ports of the acousto-optic modulator 1, the optical attenuator and the acousto-optic modulator 2 are connected to the input ports of WDM1, WDM2 and WDM3 respectively; the six output ports of WDM1 are connected to the input ports of optical orthogonal mixers 1-6 respectively, the six output ports of WDM2 are connected to the input ports of optical orthogonal mixers 7-12, and the six output ports of WDM3 are connected to the input ports of optical orthogonal mixers 13-18; the four output ports of the optical orthogonal mixer are connected to the input ports of the two balanced detectors respectively; the output ports of the two balanced detectors are connected to the two input ports of the electrical orthogonal coupler respectively; the output ports of the electrical orthogonal coupler are filtered through an electrical bandpass filter and connected to a spectrum analyzer.

[0060] 2. The laser center frequency generated by the laser is 193.1THz, and the optical power is 16dBm; the RF signal source generates a broadband signal with a center frequency of 18GHz, a bandwidth of 30GHz, and a power of 19.6dBm; the LO signal source generates a two-tone local oscillator signal with a frequency of 6GHz and 18GHz, and the sum of the signal powers is 33.1dBm; the half-wave voltage of the MZM is 5V, and the extinction ratio is 35dB; the half-wave voltage of the phase modulator is 3V; the channel frequency period of the WDM is 6GHz, and the passband frequency is consistent with each comb line of the optical comb; the responsivity of each balanced detector is 0.7A / W.

[0061] 3. Adjust the input power and phase difference of the dual-tone signal. Figure 4 : This is the 9-line optical comb diagram generated, with a center frequency of 193.1 THz and an interval of 6 GHz.

[0062] 4. Adjust AOM 1 and AOM 2 to shift the frequency of the LO optical comb. The schematic diagram of signal down-conversion is as follows: Figure 2 , Figure 3 As shown;

[0063] 5. The RF signal and LO signal are beat by an optical orthogonal mixer. The beat signal is detected by a balanced detector, then image suppressed by an electrical orthogonal coupler, and finally filtered by an electrical bandpass filter to obtain the desired signal. The signal spectrum is shown in the figure below. Figure 5 shown.

[0064] 6. In order to test the image suppression effect of the system, a broadband RF signal with a center frequency of 4.5 GHz and a bandwidth of 300 MHz in the second channel range (4–5 GHz) is used as the received signal, and another broadband RF signal with a center frequency of 7.5 GHz and a bandwidth of 150 MHz in the fifth channel range (7–8 GHz) is used as the image signal.

[0065] 7. The signal spectrum without image suppression is as follows Figure 6 As shown, the signal spectrum after the electric orthogonal coupler is as follows Figure 7 It can be seen that after passing through the electrical orthogonal coupler, the image signal is significantly suppressed.

[0066] In summary, the present application invents a large-bandwidth microwave photon channelized receiver with a simple structure and strong operability. By reasonably setting the amplitude and phase of the input LO signal and by reasonably setting the DC bias point of the modulator, a microwave photon channelized receiver capable of receiving large-bandwidth signals is finally obtained. The present invention is highly practical and can be applied to various systems that require large-bandwidth signal reception.

Claims

1. A multi-channel photon channelized receiver based on a single optical comb and acousto-optic frequency shifting, characterized in that: It includes a laser, a Mach-Zehnder modulator MZM, a phase modulator, two acousto-optic modulators, an optical attenuator, two erbium-doped fiber amplifiers, a 1×2 optical splitter, a 1×3 optical splitter, a 1×18 optical splitter, three wavelength division multiplexers WDM, an optical bandpass filter, 18 optical orthogonal mixers, 36 balanced detectors, 18 electrical orthogonal couplers and multiple electrical bandpass filters; The output port of the laser is connected to a 1×2 optical splitter, output port 1 of the 1×2 optical splitter is connected to the optical input port of the MZM, and output port 2 of the 1×2 optical splitter is connected to the optical input port of the phase modulator; The output port of the MZM is connected to the input port of the erbium-doped fiber amplifier 1, the output port of the erbium-doped fiber amplifier 1 is connected to the 1×18 splitter, and the output port of the 1×18 splitter is respectively connected to the RF input port of the optical orthogonal mixer 1 to the optical orthogonal mixer 18; wherein the RF input port of the MZM inputs the RF signal; The output port of the phase modulator is connected to the input port of the erbium-doped fiber amplifier 2, the output port of the erbium-doped fiber amplifier 2 is connected to the optical bandpass filter, the output port of the optical bandpass filter is connected to the 1×3 optical splitter, and the three output ports of the 1×3 optical splitter are respectively connected to the input ports of the acousto-optic modulator 1, the optical attenuator and the acousto-optic modulator 2; wherein the frequencies of the two local oscillator signals input to the RF input port of the phase modulator are f LO and 3f LO , the phase difference is 90°; The output ports of the acousto-optic modulator 1, the optical attenuator and the acousto-optic modulator 2 are respectively connected to the input ports of three wavelength division multiplexers WDM1, WDM2 and WDM3; the six output ports of WDM1 are respectively connected to the input ports of the optical orthogonal mixer 1 to the optical orthogonal mixer 6, the six output ports of WDM2 are respectively connected to the input ports of the optical orthogonal mixer 7 to the optical orthogonal mixer 12, and the six output ports of WDM3 are respectively connected to the input ports of the optical orthogonal mixer 13 to the optical orthogonal mixer 18; The four output ports of each optical orthogonal mixer are divided into two groups, and the two output ports in each group are respectively connected to the input ports of two balanced detectors; the output ports of every two balanced detectors are respectively connected to the two input ports of an electrical orthogonal coupler; each output port of the electrical orthogonal coupler obtains a channel of receiving signal after passing through an electrical bandpass filter.

2. A signal receiving method using the receiver as claimed in claim 1, comprising the following steps: Step 1: The laser generates a laser signal, which is output to the MZM and phase modulator respectively through a 1×2 optical splitter; Step 2: MZM is powered by RF signal V RF (t) = V0cos(ω RF t) drive, where The RF input port of the MZM inputs the RF signal, ω RF is the angular frequency of the RF signal, V0 is the strength of the RF signal, then the output expression of MZM is: In the formula, E in (t) is the laser signal output by the laser, V π is the half-wave voltage of MZM, m=πV0 / V π is the modulation index; and is the phase shift introduced by the DC bias on the upper and lower arms of the MZM, is the DC bias angle of MZM; φ is the phase difference of the RF signal loaded on the upper and lower arms of MZM; J n (·) is the nth-order Bessel function of the first kind. In the case of small signal modulation, the higher-order Bessel coefficients can be ignored. When only the first-order optical sideband is considered, equation (1) is simplified to: Set the half-wave voltage of MZM so that MZM works at the minimum point and performs suppressed carrier double-sideband modulation; Step 3: Phase modulator is composed of two-tone signal V LO (t) = V2[cos(ω1t+Δφ)+cos(ω2t)], then the output expression of the phase modulator is recorded as: Where V2 represents the intensity of the dual-tone signal, ω1 and ω2 represent the angular frequencies of the two signals, and ω2 = 2ω1, Δφ1 represents the phase difference between the two signals of the dual-tone signal, and m1 = m2 = πV2 / V π,PM , V π,PM is the half-wave voltage of the phase modulator; Step 4: Set the frequencies of the two local oscillator signals input to the phase modulator from the RF input port of the phase modulator to be f LO and 3f LO , the phase difference is 90°, and the modulation index is 1.5; after passing through the phase modulator, a center frequency of f is generated c , the frequency interval is f LO N-line optical comb; Step 5: After being amplified by an erbium-doped fiber amplifier, the N-line optical comb is divided into three paths. Two of the paths use an acousto-optic modulator to shift the frequency of each optical comb, and then use WDM to filter out the frequency f k,n =nf LO +f c +kΔf signal component, where n is an integer in the interval [-N / 2, N / 2], representing the sideband order of the optical comb line, Δf = f LO / 6 represents the frequency shift of the AOM, k=-1,0,1 represents the sequence number of each path after the optical splitting, that is, the first path is shifted down by Δf, the second path is not shifted, and the third path is shifted up by Δf; the filtered frequency is f k,n The signal is connected to the LO port of the optical orthogonal mixer and beats with the RF signal. The signal after the beat is recorded as: Where R is the responsivity of the PD, Φ + =2π(f RF +f c )t represents the phase of the RF signal, Φ k,n =2π(nf LO +f c +kΔf)t represents the phase of the LO optical frequency comb signal after frequency shift, B n represents the amplitude of the nth LO optical frequency comb; The output signals of the two balanced detectors are recorded as: Step 6: After balanced detection, only I and Q information are left in the two channels, and the second-order intermodulation distortion and DC terms are eliminated. However, since the signals are down-converted to the same intermediate frequency, spectrum aliasing will occur, that is, the intermediate frequency signals of different sub-channels are mirror images of each other. An electrical orthogonal coupler is used to separate the two mirror images of each other, and finally the required intermediate frequency signal is filtered out using an electrical bandpass filter of the same frequency; In this way, the phase modulator and the acousto-optic modulator are combined, and an LO optical comb is used, and then the acousto-optic modulator is used for frequency shifting to realize the reception of 6 channel signals; if N is an odd number, the generated optical comb contains (N-1) / 2 positive-order sidebands, which can realize the reception of up to 3(N-1) channels; if N is an even number, the generated optical comb contains N / 2 positive-order sidebands, which can realize the reception of up to 3N channels.

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