Transmit isolation microwave photonic receiving system and method based on parallel electro-optic modulators

Abstract

The application provides a transmitting-isolating microwave photon receiving system and method based on parallel electro-optical modulators, relates to the fields of photoelectric technology and modern radar, and comprises a first continuous wave laser, a second continuous wave laser, a first optical coupler, an antenna, a first Mach-Zehnder modulator, a second Mach-Zehnder modulator, a third Mach-Zehnder modulator, a first power divider, a second power divider, a first adjustable optical attenuator, a first adjustable optical delay line, a second adjustable optical attenuator, a second adjustable optical delay line, a second optical coupler and a balanced photoelectric detector. The application can realize wideband isolation based on a single antenna and simultaneously transmitting signals at the same frequency, and can realize optical self-interference cancellation technology based on a parallel electro-optical modulation structure. The application can simultaneously eliminate reflected self-interference signals caused by impedance mismatch of radio frequency connection ports and self-interference signals caused by opposite transmission modulation residues, improve the isolation degree of the transmitting-isolating microwave photon receiver, and has a large working bandwidth and high isolation degree.

Description

Technical Field

[0001] This invention relates to the fields of optoelectronic technology and modern radar, specifically to a transmit-isolated microwave photon receiving system and method based on a parallel electro-optic modulator. Background Technology

[0002] Simultaneous transmit and receive (STAR) systems have important applications in broadband wireless communication and modern radar detection. In wireless communication systems, full-duplex systems with simultaneous transmit and receive capabilities can improve the utilization of time and spectrum resources; in radar detection systems, simultaneous transmit and receive can solve the blind zone problem inherent in traditional radar detection. Isolation is one of the key parameters of STAR systems, used to characterize the degree to which the transmitted signal isolates the received signal from crosstalk. STAR systems based on long-range dual antennas can significantly improve the system's isolation. In contrast, STAR systems based on a single antenna are more compact and have potential applications in airborne and shipborne radar, small communication base stations, etc. However, due to the lack of efficient physical isolation in single-antenna transmission and reception, the transmit isolation is low. Therefore, high-isolation STAR systems based on a single antenna are a highly challenging and urgently needed application.

[0003] Traditional single-antenna simultaneous same-frequency transceiver systems use electrical circulators to isolate the transmit and receive links. However, ferrite circulators are limited by electronic bottlenecks, resulting in low isolation, limited operating bandwidth, and difficulty in operating across octave bands. In contrast, microwave photonics-based transmit-isolated receivers can significantly improve operating bandwidth by leveraging the broadband characteristics of photonics. At the same time, by utilizing the effect of high modulation efficiency when the optical carrier and modulation signal are transmitted in the same direction and low modulation efficiency when transmitted in opposite directions in an electro-optic modulator, effective isolation of the transmit signal from the receiver can be achieved (Po Dong, “Travelling-waveMach-Zehnder modulators functioning as optical isolators,” Optics Express, 23(8), 10498–10505 (2015).). To further improve isolation, non-equidistant electro-optic modulator electrodes can be designed to exacerbate the mismatch between the opposing modulation signal and the optical carrier velocity, reduce the opposing modulation efficiency, and thus improve receiver isolation (C. Cox and E. Ackerman, “TIPRx: a transmit-isolating photonic receiver,” Journal of Lightwave Technology, 32(20), 3630-3636(2014).). In addition, single-sideband modulation of the same-direction modulated received signal and the opposite-direction modulated transmitted signal is achieved using two 90° bridges, respectively. Since the modulation sidebands of both are symmetrical with respect to the optical carrier, residual modulation sidebands of the transmitted signal can be filtered out by an optical filter before photodetection, thus improving isolation (Edward I. Ackerman, Charles H. Cox, Harold V. Rousse, and Preetpaul S. Devgan, “Broadband simultaneous transmit and receive from a single antenna using improved photonic architecture” in IEEE / MTT-S International Microwave Symposium, 778-781, 2019.). However, due to the insufficiently steep edges of the optical filter's spectral response curve, this method significantly reduces the isolation for low-frequency transmitted signals. Furthermore, the isolation performance is affected by the laser output wavelength drift, placing high demands on the stability of the laser's output wavelength. Based on current research progress, the isolation of existing bidirectional electro-optic modulation transmit-isolated microwave photonic receivers still needs to be improved, and existing solutions do not consider the impact of reflected self-interference signals caused by impedance mismatch at the RF connection port on the receiver isolation. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a transmit-isolated microwave photon receiving system based on a parallel electro-optic modulator.

[0005] A transmit-isolated microwave photonic receiving system based on a parallel electro-optic modulator includes a first continuous-wave laser, a second continuous-wave laser, a first optical coupler, an antenna, a first Mach-Zehnder modulator, a second Mach-Zehnder modulator, a third Mach-Zehnder modulator, a first power divider, a second power divider, a first tunable optical attenuator, a first tunable optical delay line, a second tunable optical attenuator, a second tunable optical delay line, a second optical coupler, and a balanced photodetector.

[0006] The first and second continuous-wave lasers are both used to output optical carriers; the first, second, and third Mach-Zehnder modulators are used to modulate the optical carriers output by the lasers.

[0007] A first continuous-wave laser is connected to a first Mach-Zehnder modulator; a second continuous-wave laser is connected to a first optical coupler, which splits the optical carrier into two paths, one of which is input to a second Mach-Zehnder modulator and the other to a third Mach-Zehnder modulator; the reference signal of the reflected self-interference signal output from the second Mach-Zehnder modulator passes sequentially through a first tunable optical attenuator and a first tunable optical delay line; the reference signal of the opposing modulation signal output from the third Mach-Zehnder modulator passes sequentially through a second tunable optical attenuator and a second tunable optical delay line.

[0008] The second optical coupler is used to combine the output of the first tunable optical delay line and the output of the first Mach-Zehnder modulator and input the combined signal into the balanced photodetector.

[0009] A balanced photodetector is used to perform photoelectric conversion on the output signal of the second optical coupler and the output signal of the second tunable optical delay line.

[0010] The antenna is connected to the first Mach-Zehnder modulator for signal transmission and reception;

[0011] The first power divider is connected to the signal source and is used to split the radio frequency signal into two. One path is connected to the opposing radio frequency port of the first Mach-Zehnder modulator, and the other path is connected to the second power divider. One output of the second power divider is connected to the same-direction radio frequency port of the second Mach-Zehnder modulator, and the other output is connected to the opposing radio frequency port of the third Mach-Zehnder modulator.

[0012] Both the first and second continuous-wave lasers are distributed feedback lasers with center wavelengths located in the C-band, O-band, or L-band. As long as the continuous-wave laser is located in these bands, has a corresponding photodetector, and the wavelength difference is large enough to prevent the photodetector from detecting the difference frequency signal, the method of this invention can be achieved.

[0013] Specifically, the optical carrier frequency difference between the first continuous wave laser and the second continuous wave laser is much greater than the bandwidth of the balanced photodetector.

[0014] Specifically, the first Mach-Zehnder modulator operates at the linear bias point on the rising edge.

[0015] Specifically, the second Mach-Zehnder modulator operates at the linear bias point on the falling edge.

[0016] Specifically, the third Mach-Zehnder modulator operates at the linear bias point on the rising edge.

[0017] The reference signal output by the second Mach-Zehnder modulator, after photoelectric conversion, has the same amplitude but opposite phase as the reflected self-interference signal in the photoelectric converted signal output by the first Mach-Zehnder modulator; the reference signal output by the third Mach-Zehnder modulator, after photoelectric conversion, has the same amplitude and phase as the opposing modulation signal in the photoelectric converted signal output by the second Mach-Zehnder modulator.

[0018] Meanwhile, the present invention also provides a transmit-isolated photon receiving method based on a parallel electro-optic modulator, which is implemented using the above-mentioned transmit-isolated microwave photon receiving system based on a parallel electro-optic modulator.

[0019] After adopting the above solution, the beneficial effects of the present invention are as follows:

[0020] This invention utilizes the efficiency difference between co-directional and counter-directional transmission modulation of the optical carrier and modulation signal in bidirectional electro-optic modulation to achieve broadband isolation based on simultaneous, same-frequency transmission of signals using a single antenna. Furthermore, it employs optical self-interference cancellation technology based on a parallel electro-optic modulation structure to simultaneously eliminate reflected self-interference signals caused by impedance mismatch at the antenna RF connection ports and self-interference signals from counter-directional transmission modulation, thereby improving the isolation of the transmit-isolated microwave photonic receiver. The entire transmit-isolated receiver system boasts a large operating bandwidth, high isolation, and a compact structure, allowing for on-chip integration. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0022] Figure 2 The output spectrum of the balanced photodetector is shown in the example when the transmitted signal frequency range is from 3 GHz to 6 GHz.

[0023] Figure 3 The output spectrum of the balanced photodetector is shown in the example when the transmitted signal frequency range is 6GHz to 12GHz.

[0024] Figure 4 The output spectrum of the balanced photodetector is shown in the example when the transmitted signal frequency range is from 12GHz to 24GHz.

[0025] 1-First continuous wave laser, 2-Second continuous wave laser, 3-First optical coupler, 4-Antenna, 5-First Mach-Zehnder modulator, 6-Second MZM, 7-Third MZM, 8-Signal source, 9-First power divider, 10-Second power divider, 11-First tunable optical attenuator, 12-First tunable optical delay line, 13-Second VOA, 14-Second OTDL, 15-Second OC, 16-Balanced photodetector;

[0026] In the figure, due to image space limitations, some components are represented in smaller English terms. MZM represents Mach-Zehnder modulator, VOA represents tunable optical attenuator, OTDL represents tunable optical delay line, and OC represents optical coupler. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0028] The following is in conjunction with the appendix Figures 1-4 The present invention will be described in detail with reference to the embodiments.

[0029] like Figure 1 As shown, the transmit-isolated microwave photon receiving system based on a parallel electro-optic modulator in this specific embodiment includes a first continuous wave laser 1, a second continuous wave laser 2, a first optical coupler 3, an antenna 4, a first Mach-Zehnder modulator 5, a second Mach-Zehnder modulator, a third Mach-Zehnder modulator, a first power divider 9, a second power divider 10, a first tunable optical attenuator 11, a first tunable optical delay line 12, a second tunable optical attenuator, a second tunable optical delay line, a second optical coupler, and a balanced photodetector 16.

[0030] The first continuous wave laser 1 and the second continuous wave laser 2 are both used to output optical carriers; the first Mach-Zehnder modulator 5, the second Mach-Zehnder modulator and the third Mach-Zehnder modulator are used to modulate the optical carriers output by the lasers.

[0031] The first continuous wave laser 1 is connected to the first Mach-Zehnder modulator 5; the second continuous wave laser 2 is connected to the first optical coupler 3, which splits the optical carrier into two, one path input to the second Mach-Zehnder modulator and the other path input to the third Mach-Zehnder modulator; the reference signal of the reflected self-interference signal output from the second Mach-Zehnder modulator passes sequentially through the first tunable optical attenuator 11 and the first tunable optical delay line 12; the reference signal of the opposing modulation signal output from the third Mach-Zehnder modulator passes sequentially through the second tunable optical attenuator and the second tunable optical delay line.

[0032] The second optical coupler is used to combine the output of the first tunable optical delay line 12 and the output of the first Mach-Zehnder modulator 5 and input the combined signal into the balanced photodetector 16.

[0033] The balanced photodetector 16 is used to perform photoelectric conversion on the output signal of the second optical coupler and the output signal of the second tunable optical delay line.

[0034] Antenna 4 is connected to the first Mach-Zehnder modulator 5 for signal transmission and reception;

[0035] Signal source 8 is used to generate radio frequency signals; the first power divider 9 is connected to signal source 8 and is used to split the radio frequency signal into two, one of which is connected to the opposing radio frequency port of the first Mach-Zehnder modulator 5, and the other is connected to the second power divider 10. Output one of the second power divider 10 is connected to the same-direction radio frequency port of the second Mach-Zehnder modulator, and output two of the second power divider 10 is connected to the opposing radio frequency port of the third Mach-Zehnder modulator.

[0036] The reference signal output by the second Mach-Zehnder modulator, after photoelectric conversion, has the same amplitude but opposite phase as the reflected self-interference signal in the signal output by the first Mach-Zehnder modulator 5 after photoelectric conversion; the reference signal output by the third Mach-Zehnder modulator, after photoelectric conversion, has the same amplitude and phase as the opposing modulation signal in the signal output by the second Mach-Zehnder modulator after photoelectric conversion.

[0037] For the transmit-isolated microwave photonic receiving system based on a parallel electro-optic modulator in this embodiment, the optical carrier output from the first continuous-wave laser 1 is input to the first Mach-Zehnder modulator. The optical carrier output from the second continuous-wave laser 2 is split into two by the first optical coupler 3, one input to the second Mach-Zehnder modulator and the other input to the third Mach-Zehnder modulator. The frequency difference between the optical carriers of the first continuous-wave laser 1 and the second continuous-wave laser 2 is greater than the bandwidth of the balanced photodetector 16. The radio frequency signal output from the signal source 8 is split into two paths by the first power divider 9. One path enters from the opposing radio frequency port (the radio frequency drive port near the optical output end) of the first Mach-Zehnder modulator 5, passes through the electrodes of the first Mach-Zehnder modulator 5, and is then output from the co-directional radio frequency port (the radio frequency drive port near the optical input end of the modulator) to the antenna 4, and finally transmitted through the antenna 4. The first Mach-Zehnder modulator 5 operates at the linear bias point on the rising edge. The other RF signal output from the first power divider 9 is split into two paths by the second power divider 10: one path enters from the co-directional RF port of the second Mach-Zehnder modulator to perform co-directional modulation on the optical carrier, generating a reference signal for eliminating reflected self-interference signals; the other path enters from the opposing RF port of the third Mach-Zehnder modulator to perform opposing modulation on the optical carrier, generating a reference signal for eliminating opposing modulation signals. The second Mach-Zehnder modulator operates at the linear bias point on the falling edge, and the third Mach-Zehnder modulator operates at the linear bias point on the rising edge. Then, the reference signal for reflected self-interference signals output from the second Mach-Zehnder modulator passes sequentially through the first adjustable optical attenuator 11 (adjustable optical attenuator) and the first adjustable optical delay line 12 (adjustable optical delay line), while the reference signal for residual opposing modulation signals output from the third Mach-Zehnder modulator passes sequentially through the second adjustable optical attenuator and the second adjustable optical delay line. Finally, the outputs of the first tunable optical delay line 12 and the first Mach-Zehnder modulator 5 are combined through the second optical coupler and then input into the balanced photodetector 16 for photoelectric conversion. The output of the second tunable optical delay line is input into the other port of the balanced photodetector 16 for photoelectric conversion. The differential characteristics of the balanced detector are then used to eliminate reflected self-interference signals and opposing residual modulation signals in the electrical domain. Specifically, to eliminate reflected self-interference signals, the first tunable optical attenuator 11 and the first tunable optical delay line 12 are adjusted so that the reference signal output from the second Mach-Zehnder modulator, after photoelectric conversion, has the same amplitude but opposite phase as the reflected self-interference signal in the photoelectric converted signal output from the first Mach-Zehnder modulator 5. To eliminate opposing modulation signals, the second tunable optical attenuator and the second tunable optical delay line are adjusted so that the reference signal output from the third Mach-Zehnder modulator, after photoelectric conversion, has the same amplitude and phase as the opposing modulation signal in the photoelectric converted signal output from the second Mach-Zehnder modulator.

[0038] In this embodiment, the first continuous-wave laser 1 is a distributed feedback laser with a center wavelength of 1550nm, and the second continuous-wave laser 2 is a distributed feedback laser with a center wavelength of 1554nm. There are no specific limitations on the wavelengths of the first and second continuous-wave lasers, as long as the wavelength difference between them is greater than the bandwidth of the flat-plate photoelectric balance detector. The signal source 8 generates a broadband linear frequency modulated signal with a frequency range of 3GHz to 6GHz. The reflection coefficient caused by the RF port impedance mismatch is 0.1-0.2. The frequency range and reflection coefficient of the signal source 8 are not limited; this is a specific implementation. To distinguish between the transmitted and received signals, the target reflected signal is assumed to be a single-tone signal with a frequency of 4.2GHz, and the target distance from the antenna is 200m. The bias voltages of the first Mach-Zehnder modulator 5, the second Mach-Zehnder modulator, and the third Mach-Zehnder modulator are respectively... Where V π The voltage is the half-wave voltage of the three Mach-Zehnder modulators. The optical carrier output from the first continuous-wave laser 1 enters the first Mach-Zehnder modulator 5. The optical carrier output from the second continuous-wave laser 2 is split into two paths by the first coupler 3, one path entering the second Mach-Zehnder modulator and the other entering the third Mach-Zehnder modulator. The broadband transmission signal output from the signal source 8 is split into two by the first power divider 9. One path drives the opposing RF port of the first Mach-Zehnder modulator 5, and the other path enters the second power divider 10 and is split into two, driving the co-directional RF port of the second Mach-Zehnder modulator and the opposing RF port of the third Mach-Zehnder modulator, respectively. The electrical signal entering the opposing RF port of the first Mach-Zehnder modulator 5 passes through the electrodes of the first Mach-Zehnder modulator 5 and is transmitted from the co-directional RF port of the first Mach-Zehnder modulator 5 through the antenna 4. The target signal received by the antenna 4 and the reflected self-interference signal caused by the impedance mismatch of the RF port together drive the co-directional RF port of the first Mach-Zehnder modulator 5. The optical carrier entering the first Mach-Zehnder modulator 5 is modulated in the same direction by the reflected interference signal and the received signal, and modulated in opposite directions by the transmitted signal. The optical carrier entering the second Mach-Zehnder modulator is modulated in the same direction by the electrical signal, and the optical carrier entering the third Mach-Zehnder modulator is modulated in opposite directions by the electrical signal. The output optical signal of the second Mach-Zehnder modulator sequentially enters the first adjustable optical attenuator 11 and the first adjustable optical delay line 12. The output optical signal of the third Mach-Zehnder modulator sequentially enters the second adjustable optical attenuator and the second adjustable optical delay line. The optical signals from the first adjustable optical delay line 12 and the first Mach-Zehnder modulator 5 are combined into a single optical signal after passing through the second optical coupler. The optical signal output from the second optical coupler enters the balanced photodetector 16 for photoelectric conversion. The optical signal output from the second adjustable optical delay line enters the other port of the balanced photodetector 16 for photoelectric conversion.

[0039] Figure 2 This is the normalized spectrum of the output from the balanced photodetector 16. The dashed line represents the output spectrum when the first tunable optical delay line 12 and the second tunable optical delay line are disconnected, i.e., without optical self-interference signal cancellation. The solid line represents the output spectrum after optical self-interference signal cancellation. Figure 2 It can be seen that without optical self-interference signal cancellation, the target signal is overwhelmed by self-interference signals and cannot be identified. When optical self-interference signal cancellation is used, the self-interference signal suppression ratio is ≥15dB in the 3.65GHz to 4.75GHz frequency range and ≥25dB ​​in the 4.0GHz to 4.4GHz frequency range. Therefore, the self-interference signal cancellation technology achieves an improvement of 15dB isolation in the 1.1GHz bandwidth and 25dB isolation in the 400MHz bandwidth at the 4GHz frequency band.

[0040] When the transmitted signal frequency is in the range of 6GHz to 12GHz Figure 3 The normalized spectrum of the output of the 1616 photodetector is shown. When optical self-interference signal cancellation is used, the self-interference signal suppression ratio (SNR) is ≥15dB in the frequency range of 7.3GHz to 7.9GHz and ≥25dB ​​in the frequency range of 7.55GHz to 7.75GHz. This demonstrates that the self-interference signal cancellation technology achieves an improvement of 15dB isolation over a 600MHz bandwidth and 25dB isolation over a 200MHz bandwidth in the 7.5GHz band.

[0041] When the transmitted signal frequency is in the range of 12GHz to 24GHz Figure 4 The normalized spectrum of the output of the photodetector 16 is shown. When optical self-interference signal cancellation is used, the self-interference signal suppression ratio is ≥15dB in the frequency ranges of 13.9GHz to 15GHz, 17.4GHz to 18.3GHz, and 20.9GHz to 21.6GHz; and ≥25dB ​​in the frequency range of 17.75GHz to 17.95GHz. This demonstrates that the self-interference signal cancellation technology achieves a 15dB isolation improvement with a 1.1GHz bandwidth at 14GHz, a 15dB isolation improvement with a 900MHz bandwidth and a 25dB isolation improvement with a 200MHz bandwidth at 17GHz, and a 15dB isolation improvement with a 700MHz bandwidth at 21GHz. This effectively improves the isolation of transmitted signals and the detection capability of weak targets in a single-antenna simultaneous same-frequency transceiver system.

[0042] As can be seen from specific examples, the present invention provides a transmit-isolated photonic receiver scheme based on a parallel electro-optic modulator, which can effectively improve the isolation of the transmit-isolated microwave photonic receiver over a wide bandwidth.

[0043] This invention is not limited to the above-described embodiments, and several equivalent modifications and substitutions can be made. The laser wavelength is not limited to 1550nm and 1554nm, the type of transmitted signal is not limited to linear frequency modulated signal, and the transmitted and received signals are not limited to the range of 3GHz to 24GHz. Various simplifications and modifications within the scope of the principle and method of this invention are all protected by this invention.

Claims

1. A transmit-isolated microwave photon receiving system based on a parallel electro-optic modulator, characterized in that, It includes a first continuous wave laser, a second continuous wave laser, a first optical coupler, an antenna, a first Mach-Zehnder modulator, a second Mach-Zehnder modulator, a third Mach-Zehnder modulator, a first power divider, a second power divider, a first tunable optical attenuator, a first tunable optical delay line, a second tunable optical attenuator, a second tunable optical delay line, a second optical coupler, and a balanced photodetector. The first and second continuous-wave lasers are both used to output optical carriers; the first, second, and third Mach-Zehnder modulators are used to modulate the optical carriers output by the lasers. The first continuous wave laser is connected to the first Mach-Zehnder modulator; The second continuous wave laser is connected to the first optical coupler, which splits the optical carrier into two paths: one path is input to the second Mach-Zehnder modulator, and the other path is input to the third Mach-Zehnder modulator. The reference signal of the reflected self-interference signal output from the second Mach-Zehnder modulator passes through the first tunable optical attenuator and the first tunable optical delay line in sequence. The reference signal of the counter-modulation signal output from the third Mach-Zehnder modulator passes through the second tunable optical attenuator and the second tunable optical delay line in sequence. The second optical coupler is used to combine the output of the first tunable optical delay line and the output of the first Mach-Zehnder modulator and input the combined signal into the balanced photodetector. A balanced photodetector is used to perform photoelectric conversion on the output signal of the second optical coupler and the output signal of the second tunable optical delay line. The antenna is connected to the first Mach-Zehnder modulator for signal transmission and reception; The first power divider is connected to the signal source and is used to split the radio frequency signal into two. One path is connected to the opposing radio frequency port of the first Mach-Zehnder modulator, and the other path is connected to the second power divider. One output of the second power divider is connected to the same-direction radio frequency port of the second Mach-Zehnder modulator, and the other output is connected to the opposing radio frequency port of the third Mach-Zehnder modulator.

2. The transmit-isolated microwave photon receiving system based on a parallel electro-optic modulator according to claim 1, characterized in that, The wavelength difference between the first continuous-wave laser and the second continuous-wave laser is greater than the bandwidth of the balanced photodetector.

3. The transmit-isolated microwave photon receiving system based on a parallel electro-optic modulator according to claim 1, characterized in that, Both the first and second continuous wave lasers are distributed feedback lasers with a center wavelength located in the C-band, O-band, or L-band.

4. The transmit-isolated microwave photon receiving system based on a parallel electro-optic modulator according to claim 1, characterized in that, The first Mach-Zehnder modulator operates at the linear bias point on the rising edge.

5. The transmit-isolated microwave photon receiving system based on a parallel electro-optic modulator according to claim 1, characterized in that, The second Mach-Zehnder modulator operates at the linear bias point on the falling edge.

6. The transmit-isolated microwave photon receiving system based on a parallel electro-optic modulator according to claim 1, characterized in that, The third Mach-Zehnder modulator operates at the linear bias point on the rising edge.

7. The transmit-isolated microwave photon receiving system based on a parallel electro-optic modulator according to claim 1, characterized in that, The reference signal output by the second Mach-Zehnder modulator, after photoelectric conversion, has the same amplitude but opposite phase as the reflected self-interference signal in the photoelectric converted signal output by the first Mach-Zehnder modulator; the reference signal output by the third Mach-Zehnder modulator, after photoelectric conversion, has the same amplitude and phase as the opposing modulation signal in the photoelectric converted signal output by the second Mach-Zehnder modulator.

8. A transmit-isolated microwave photon receiving method based on a parallel electro-optic modulator, characterized in that, It is implemented using the transmit-isolated microwave photon receiver system based on a parallel electro-optic modulator as described in any one of claims 1-7.

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