A large instantaneous bandwidth photon-assisted radio frequency cancellation method and device
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- 10TH RES INST OF CETC
- Filing Date
- 2026-02-13
- Publication Date
- 2026-06-16
Smart Images
Figure CN122226151A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of microwave photonic radio frequency cancellation technology, and particularly relates to a photonic-assisted radio frequency cancellation method and apparatus with a large instantaneous bandwidth. Background Technology
[0002] With the development trend of open architecture and integrated aperture fusion in multifunctional RF sensors, the simultaneous operation of multiple devices and overlapping frequency bands of multiple systems make receivers susceptible to interference from strong local transmitted signals, leading to challenges such as decreased receiver sensitivity and power saturation. RF cancellation technology directly acquires interference sources from the same platform as reference signals and performs amplitude, phase, and delay matching with the received interference signals to achieve in-band interference suppression, thereby improving the receiver's ability to cope with broadband noise and the resulting power saturation. RF cancellation technology not only solves the problem of self-interference in wireless communication and radar systems but also breaks through the limitations of traditional time-division and frequency-division methods, enabling simultaneous full-duplex operation on the same frequency and improving spectrum efficiency.
[0003] Self-interference cancellation based on electrical technology uses radio frequency phase shifters, attenuators, etc., to regulate the phase and amplitude of the reference signal, ultimately suppressing interference signals at the receiver. However, due to performance bottlenecks such as narrow operating bandwidth, high loss, and low delay accuracy of electrical devices, it is difficult to effectively suppress high-frequency, large instantaneous bandwidth interference signals, thus failing to meet the radio frequency cancellation performance requirements of future high-frequency broadband applications.
[0004] Microwave photonics technology combines the advantages of ultra-high speed and wide bandwidth of photonics with the high precision of electronics. Based on microwave photonics, it is possible to achieve broadband, highly consistent amplitude and phase control, thereby effectively suppressing high-frequency, large-instantaneous-bandwidth interference signals. In 2015, Princeton University proposed an optical RF cancellation scheme based on cross-gain modulation of a semiconductor optical amplifier. During cross-gain modulation, the information carried by the signal light is inverted and modulated onto the probe light, thus using the resulting inverted reference signal to cancel out the interference signal in the received signal. This scheme can achieve fast tuning, but the semiconductor optical amplifier introduces additional noise and nonlinear effects. In 2017, Dalian University of Technology proposed an optical RF cancellation scheme based on phase modulation and optical single-sideband filtering. Utilizing the inverted characteristics of the upper and lower sidebands of phase modulation, the reference signal and the interference signal in the received signal coherently cancel each other after photoelectric conversion, achieving a cancellation depth of over 20dB for interference signals with a bandwidth of 630MHz in the X-band. However, this scheme is limited by the filtering bandwidth and roll-off factor of the optical filter, resulting in poor performance for mid- and low-frequency signals.
[0005] In summary, while microwave photonic radio frequency cancellation technology can improve the system's operating frequency band and expand the cancellation bandwidth to some extent, it is difficult to guarantee broadband phase consistency, resulting in a low cancellation depth for large instantaneous bandwidth interference signals. It is also limited by noise introduced by active devices, nonlinearity causing signal-to-noise ratio degradation, and insufficient precision of optical filters leading to limited operating frequency bands. Summary of the Invention
[0006] The purpose of this application is to address the problem that the current microwave photonic radio frequency cancellation technology is difficult to guarantee broadband phase shift consistency, resulting in low cancellation depth for large instantaneous bandwidth interference signals. This application discloses a photonic-assisted radio frequency cancellation method and device with large instantaneous bandwidth, which can achieve high consistency and high cancellation depth suppression of broadband radio frequency interference signals. It is suitable for scenarios such as simultaneous full-duplex radio frequency transceiver and multi-sensor aperture fusion, and can be widely used in radar, communication, electronic warfare and multi-functional integrated electronic information systems.
[0007] On the one hand, the objective of this application is achieved through the following technical solution: A photon-assisted radio frequency cancellation method with a large instantaneous bandwidth, the photon-assisted radio frequency cancellation method includes: a laser outputs a DC optical carrier, and the optical carrier is divided into three branches—a receiving path, a reference path, and a pump path—by an optical beam splitter; In the receiving path, the target signal and the interference signal are jointly loaded onto the optical carrier through electro-optic intensity modulation; In the reference path, the reference signal, which originates from the same source as the interference signal, is converted into an optical signal through optical single-sideband modulation; In the pump path, a dual-tone pump optical signal is generated by optically suppressed carrier double-sideband modulation. The reference optical signal and the dual-tone pump optical signal are transmitted in opposite directions in a highly nonlinear optical fiber, and the phase of the optical carrier in the reference optical signal is changed by the stimulated Brillouin scattering effect. The phase-modulated reference optical signal beats the received optical signal at the same frequency, and the reference signal and the interference signal coherently cancel each other out, ultimately outputting the target received signal.
[0008] According to a preferred embodiment, the laser outputs a DC optical carrier. Its expression is:
[0009] in, and These are the amplitude and angular frequency of the optical carrier wave, respectively. Represents the imaginary unit. Indicates time.
[0010] According to a preferred embodiment, in the receiving path, the target signal is ignored, and the interference signal is obtained by electro-optic modulation applied to the DC optical carrier output by the laser. Its expression is:
[0011] in, and These are the modulation coefficient and angular frequency of the interference signal, respectively. Represents the 0th order Bessel function. This represents a first-order Bessel function.
[0012] According to a preferred embodiment, in the reference path, a reference signal originating from the same source as the interference signal is modulated onto the DC optical carrier output by the laser to obtain a signal. Its expression is:
[0013] in, and These are the modulation coefficient and angular frequency of the interference signal, respectively.
[0014] According to a preferred embodiment, in the pump path, the angular frequency is A single-tone signal, modulated with suppressed carrier double-sideband, is applied to the DC optical carrier output by the laser to obtain a two-tone pump signal. Its expression is:
[0015] in, The modulation coefficient of the pump signal.
[0016] According to a preferred embodiment, the dual-tone pump optical signal is fed back into a highly nonlinear optical fiber through an optical circulator to excite stimulated Brillouin scattering, thereby affecting the optical carrier signal in the reference path. Apply a phase shift related to the pump light frequency and power. Obtain the phase-shifted optical carrier signal Its expression is: .
[0017] According to a preferred embodiment, the optical signal in the reference path is combined with the optical signal in the receiving path through an optical circulator, and the signal is obtained after amplitude and delay matching is achieved through an adjustable optical attenuator and an adjustable delay line. Together they enter the photodetector beat frequency, the expression of which is:
[0018] in, and These are the amplitudes of the interference signal and the reference signal, respectively. The delay introduced by the adjustable delay line is due to the fact that the reference signal and the interference signal originate from the same source. By matching amplitude and delay, i.e. ,and At this point, the reference signal and the interference signal coherently cancel each other out, thus achieving radio frequency self-interference cancellation.
[0019] On the other hand, this application also discloses: A photon-assisted radio frequency cancellation device with a large instantaneous bandwidth, wherein the photon-assisted radio frequency cancellation device performs radio frequency cancellation using the aforementioned method. The photon-assisted radio frequency cancellation device includes: Lasers, optical beam splitters, intensity modulator 1, intensity modulator 2, dual-drive modulators, adjustable delay lines, highly nonlinear optical fibers, dispersion-compensating optical fibers, circulators, optical amplifiers, adjustable attenuators, optical combiners, and photodetectors. The output port of the laser is connected to the optical input port of the optical beam splitter, and the three optical output ports of the optical beam splitter are respectively connected to the optical input ports of intensity modulator 1, dual-drive modulator and intensity modulator 2; The output port of intensity modulator 1 is connected to the optical input port of adjustable delay line, and the optical output port of adjustable delay line is connected to one input port of optical combiner to form a receiving path; The optical input port of the dual-drive modulator is connected to the left end of the highly nonlinear fiber, the right end of the highly nonlinear fiber is connected to the left end of the dispersion compensation fiber, and the right end of the dispersion compensation fiber is connected to the second interface of the circulator to form a reference path. The output port of intensity modulator 2 is connected to the optical input port of optical amplifier, and the optical output port of optical amplifier is connected to the first interface of circulator, forming a pump path; The third interface of the circulator is connected to the optical input port of the adjustable attenuator, the optical output port of the adjustable attenuator is connected to one input port of the optical combiner, and the optical output port of the optical combiner is connected to the optical input port of the photodetector.
[0020] According to a preferred embodiment, the laser is used to provide a narrow linewidth optical carrier as a seed light source, and the optical beam splitter is used to split one optical carrier into three branches. The intensity modulator 1 is used to modulate the received broadband signal onto the optical carrier, and the adjustable delay line is used to adjust the relative delay between the signal path and the reference path. The dual-drive modulator is used to modulate the reference signal onto the optical carrier, the highly nonlinear fiber is used to generate the stimulated Brillouin effect, and the dispersion compensation fiber is used to compensate for the dispersion introduced by the highly nonlinear fiber. The intensity modulator 1 is used to generate a two-tone optical carrier, and the optical amplifier is used to increase the power of the two-tone optical carrier to above the threshold of stimulated Brillouin scattering. The circulator is used for directional transmission of optical signals, the adjustable attenuator is used to adjust the relative power between the signal path and the reference path, and the photodetector is used to convert the optical signal into an electrical signal.
[0021] According to a preferred embodiment, the intensity modulator 1 is biased at the linear transmission point to achieve double-sideband modulation; The driving radio frequency signals applied to the upper and lower arms of the dual-drive modulator have a 90-degree phase difference and are biased at the linear transmission point to achieve single-sideband modulation, thereby changing the phase of the electrical signal after beat frequency by changing the phase of the optical carrier. The intensity modulator 2 is biased at the minimum transmission point to suppress the generation of dual-tone optical carriers by double-sideband modulation. By controlling the power and frequency of the dual-tone optical carriers, the phase of the reference optical signal carrier is modulated. The power of the dual-tone optical carriers can be adjusted by an optical amplifier, and the frequency of the dual-tone optical carriers is controlled by the driving frequency of the intensity modulator 2. The dispersion-compensating fiber and the highly nonlinear fiber introduce the same numerical value of dispersion, but with opposite signs.
[0022] The aforementioned main solution and its various further alternative solutions can be freely combined to form multiple solutions, all of which are solutions that can be adopted and are claimed in this application. Those skilled in the art, after understanding the solution of this application, will realize that there are many combinations based on the prior art and common general knowledge, all of which are technical solutions to be protected in this application, and will not be exhaustively listed here.
[0023] The beneficial effects of this application are: This application utilizes single-sideband modulation combined with stimulated Brillouin scattering to achieve phase modulation of the reference signal. Compared with other schemes, it has advantages such as good phase tuning consistency and strong broadband applicability, thereby achieving high suppression ratio RF self-interference elimination.
[0024] This application employs dispersion-compensating fiber to compensate for the dispersion introduced by highly nonlinear fiber, thus avoiding the impact of frequency-dependent phase shift on the phase of the broadband reference signal in long-distance fiber transmission. Attached Figure Description
[0025] Figure 1 This is a schematic diagram of the structure of this application; Figure 2 The simulation results of dual-tone radio frequency self-interference suppression are shown in the figure. Detailed Implementation
[0026] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, unless otherwise specified, the following embodiments and features in the embodiments can be combined with each other.
[0027] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0028] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application 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 on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0029] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" 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 can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0030] Furthermore, it should be noted that unless otherwise specified in this application, the specific structures, connections, positions, power sources, etc. involved are all things that a person skilled in the art can know without creative effort based on the prior art.
[0031] Example 1 This embodiment discloses a photon-assisted radio frequency cancellation method with a large instantaneous bandwidth, which includes the following steps.
[0032] The laser outputs a DC optical carrier, which is then split into three branches—a receiving path, a reference path, and a pump path—by an optical beam splitter. In the receiving path, the target received signal and the interference signal are jointly loaded onto the optical carrier through electro-optic intensity modulation; in the reference path, the reference signal, which is of the same origin as the interference signal, is converted into an optical signal through optical single-sideband modulation; in the pump path, a dual-tone pump optical signal is generated by optical suppression carrier double-sideband modulation.
[0033] The reference optical signal and the dual-tone pump optical signal are transmitted in opposite directions in a highly nonlinear optical fiber. The phase of the optical carrier in the reference optical signal is changed by the stimulated Brillouin scattering effect. The phase-modulated reference optical signal beats the received optical signal, and the reference signal and the interference signal coherently cancel each other out, finally outputting the target received signal.
[0034] Preferably, the laser outputs a DC optical carrier. Its expression is:
[0035] in, and These are the amplitude and angular frequency of the optical carrier wave, respectively.
[0036] Preferably, in the receiving path, the target signal is ignored, and the interference signal is obtained by electro-optic modulation onto the DC optical carrier output by the laser. Its expression is:
[0037] in, and These are the modulation coefficient and angular frequency of the interference signal, respectively. express?, express?.
[0038] Preferably, in the reference path, a reference signal originating from the same source as the interference signal is modulated onto the DC optical carrier output by the laser to obtain a signal. Its expression is:
[0039] in, and These are the modulation coefficient and angular frequency of the interference signal, respectively.
[0040] Preferably, in the pump path, the angular frequency is A single-tone signal, modulated with suppressed carrier double-sideband, is applied to the DC optical carrier output by the laser to obtain a two-tone pump signal. Its expression is:
[0041] in, The modulation coefficient of the pump signal.
[0042] Preferably, the dual-tone pump optical signal is fed back into the highly nonlinear optical fiber through an optical circulator to excite stimulated Brillouin scattering, thereby affecting the optical carrier signal in the reference path. Apply a phase shift related to the pump light frequency and power. Obtain the phase-shifted optical carrier signal Its expression is: .
[0043] Preferably, the optical signal in the reference path is combined with the optical signal in the receiving path through an optical circulator, and the signal is obtained after amplitude and delay matching is achieved through an adjustable optical attenuator and an adjustable delay line. Together they enter the photodetector beat frequency, the expression of which is:
[0044] in, and These are the amplitudes of the interference signal and the reference signal, respectively. The delay introduced by the adjustable delay line is due to the fact that the reference signal and the interference signal originate from the same source. By matching amplitude and delay, i.e. ,and At this point, the reference signal and the interference signal coherently cancel each other out, thus achieving radio frequency self-interference cancellation.
[0045] Example 2 refer to Figure 1 As shown, based on Embodiment 1, this embodiment discloses a photon-assisted radio frequency cancellation device with a large instantaneous bandwidth. The photon-assisted radio frequency cancellation device uses the method of Embodiment 1 to perform radio frequency cancellation.
[0046] Specifically, the photon-assisted radio frequency cancellation device includes: a laser, an optical beam splitter, an intensity modulator 1, an intensity modulator 2, a dual-drive modulator, an adjustable delay line, a highly nonlinear optical fiber, a dispersion-compensating optical fiber, a circulator, an optical amplifier, an adjustable attenuator, an optical combiner, and a photodetector.
[0047] Preferably, the output port of the laser is connected to the optical input port of the optical beam splitter, and the three optical output ports of the optical beam splitter are respectively connected to the optical input ports of intensity modulator 1, dual-drive modulator and intensity modulator 2.
[0048] The output port of intensity modulator 1 is connected to the optical input port of adjustable delay line, and the optical output port of adjustable delay line is connected to an input port of optical combiner to form a receiving path.
[0049] The optical input port of the dual-drive modulator is connected to the left end of the highly nonlinear fiber, the right end of the highly nonlinear fiber is connected to the left end of the dispersion compensation fiber, and the right end of the dispersion compensation fiber is connected to the second interface of the circulator, forming a reference path.
[0050] The output port of intensity modulator 2 is connected to the optical input port of optical amplifier, and the optical output port of optical amplifier is connected to the first interface of circulator, forming a pump path.
[0051] Furthermore, the third interface of the circulator is connected to the optical input port of the adjustable attenuator, the optical output port of the adjustable attenuator is connected to one input port of the optical combiner, and the optical output port of the optical combiner is connected to the optical input port of the photodetector.
[0052] Preferably, the laser is used to provide a narrow linewidth optical carrier as a seed light source, and the optical beam splitter is used to split one optical carrier into three branches.
[0053] In the receiving path, the intensity modulator 1 is used to modulate the received broadband signal onto the optical carrier, and the adjustable delay line is used to adjust the relative delay between the signal path and the reference path.
[0054] In the reference path, the dual-drive modulator is used to modulate the reference signal onto the optical carrier, the highly nonlinear fiber is used to generate the stimulated Brillouin effect, and the dispersion compensation fiber is used to compensate for the dispersion introduced by the highly nonlinear fiber.
[0055] In the pump circuit, the intensity modulator 1 is used to generate a two-tone optical carrier, and the optical amplifier is used to increase the power of the two-tone optical carrier to above the threshold of stimulated Brillouin scattering.
[0056] Furthermore, the circulator is used for directional transmission of optical signals, the adjustable attenuator is used to adjust the relative power between the signal path and the reference path, and the photodetector is used to convert the optical signal into an electrical signal.
[0057] Preferably, the intensity modulator 1 is biased at the linear transmission point to achieve double-sideband modulation, thereby ensuring the linear operating characteristics of the system.
[0058] The driving radio frequency signals applied to the upper and lower arms of the dual-drive modulator have a 90-degree phase difference and are biased at the linear transmission point to achieve single-sideband modulation. This allows the phase of the electrical signal after beat frequency to be changed by changing the phase of the optical carrier.
[0059] The intensity modulator 2 is biased at the minimum transmission point to suppress the generation of dual-tone optical carriers by double-sideband modulation. By controlling the power and frequency of the dual-tone optical carriers, the phase of the reference optical signal carrier is modulated. The power of the dual-tone optical carriers can be adjusted by an optical amplifier, and the frequency of the dual-tone optical carriers is controlled by the driving frequency of the intensity modulator 2.
[0060] Dispersion-compensated fiber and highly nonlinear fiber introduce the same amount of dispersion, but with opposite signs. This avoids phase inconsistencies caused by dispersion when broadband signals are transmitted in the fiber.
[0061] After the reference optical signal is matched with the received optical signal in terms of amplitude and delay, it achieves coherent cancellation with the interference signal after photoelectric conversion, thereby significantly suppressing the self-interference signal.
[0062] In the following optional embodiments, the following is adopted: Figure 1 The structure and principle shown are simulated to realize a photon-assisted radio frequency cancellation system based on stimulated Brillouin scattering, and to verify that it can achieve high cancellation depth suppression of broadband self-interference signals.
[0063] In one alternative embodiment, the laser has a center frequency of 193.1 THz and is split into three branches by an optical beam splitter.
[0064] In the receiving path, the target signal is ignored, and dual-tone radio frequency signals with frequencies of 12GHz and 16GHz are modulated onto the optical carrier by intensity modulator 1 as self-interference signals to verify the cancellation capability of the invention within an instantaneous bandwidth of 4GHz.
[0065] In the reference path, the dual-tone radio frequency signal, which is the same as the self-interference signal, generates a single-sideband modulated signal through a dual-drive modulator. The Brillouin frequency shift of the highly nonlinear fiber is 9.654 GHz, and the dispersion it introduces can be compensated by dispersion-compensating fiber.
[0066] In the pump circuit, a single-tone radio frequency signal with a frequency of 9.659 GHz drives intensity modulator 2 to generate a dual-tone pump optical signal, the power of which can be tuned by an optical amplifier.
[0067] A dual-tone pump optical signal enters a highly nonlinear optical fiber from right to left in a reverse direction, exciting stimulated Brillouin scattering. The carrier phase of the reference optical signal is modulated by controlling the output power of the optical amplifier. The reference optical signal after stimulated Brillouin scattering is combined with the received optical signal and sent to a photodetector for photoelectric conversion. Figure 2 (a) shows the RF simulation results when the reference path is disconnected and the optical signal of the receiving path enters the photodetector alone. It can be seen that the power of the interference signal at frequencies of 12 GHz and 16 GHz exceeds 0 dBm. Figure 2 (b) shows the RF spectrum simulation results when the received optical signal and the reference optical signal enter the photodetector together. It can be seen that by using the photon-assisted RF cancellation method of the present invention, the power of the interference signals with frequencies of 12 GHz and 16 GHz is suppressed to -80 dBm, and the cancellation depth reaches 80 dBm in the 4 GHz instantaneous bandwidth.
[0068] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A photon-assisted radio frequency cancellation method with a large instantaneous bandwidth, characterized in that, The photon-assisted radio frequency cancellation method includes: a laser outputs a DC optical carrier, which is then split into three branches—a receiving path, a reference path, and a pump path—by an optical beam splitter. In the receiving path, the target signal and the interference signal are jointly loaded onto the optical carrier through electro-optic intensity modulation; In the reference path, the reference signal, which originates from the same source as the interference signal, is converted into an optical signal through optical single-sideband modulation; In the pump path, a dual-tone pump optical signal is generated by optically suppressed carrier double-sideband modulation. The reference optical signal and the dual-tone pump optical signal are transmitted in opposite directions in a highly nonlinear optical fiber, and the phase of the optical carrier in the reference optical signal is changed by the stimulated Brillouin scattering effect. The phase-modulated reference optical signal beats the received optical signal at the same frequency, and the reference signal and the interference signal coherently cancel each other out, ultimately outputting the target received signal.
2. The photon-assisted radio frequency cancellation method with large instantaneous bandwidth as described in claim 1, characterized in that, Laser output DC optical carrier Its expression is: in, and These are the amplitude and angular frequency of the optical carrier wave, respectively. Represents the imaginary unit. Indicates time.
3. The photon-assisted radio frequency cancellation method with large instantaneous bandwidth as described in claim 2, characterized in that, In the receiving path, the target signal is ignored, and the interference signal is obtained by electro-optic modulation applied to the DC optical carrier output by the laser. Its expression is: in, and These are the modulation coefficient and angular frequency of the interference signal, respectively. Represents the 0th order Bessel function. This represents a first-order Bessel function.
4. The photon-assisted radio frequency cancellation method with large instantaneous bandwidth as described in claim 3, characterized in that, In the reference path, a reference signal originating from the same source as the interference signal is modulated onto the DC optical carrier output by the laser to obtain a signal. Its expression is: in, and These are the modulation coefficient and angular frequency of the interference signal, respectively.
5. The photon-assisted radio frequency cancellation method with large instantaneous bandwidth as described in claim 4, characterized in that, In the pump circuit, the angular frequency is A single-tone signal, modulated with suppressed carrier double-sideband, is applied to the DC optical carrier output by the laser to obtain a two-tone pump signal. Its expression is: in, The modulation coefficient of the pump signal.
6. The photon-assisted radio frequency cancellation method with large instantaneous bandwidth as described in claim 5, characterized in that, The dual-tone pump optical signal is fed back into the highly nonlinear optical fiber through an optical circulator to excite stimulated Brillouin scattering, which affects the optical carrier signal in the reference path. Apply a phase shift related to the pump light frequency and power. Obtain the phase-shifted optical carrier signal Its expression is: 。 7. The photon-assisted radio frequency cancellation method with large instantaneous bandwidth as described in claim 6, characterized in that, The optical signal in the reference path is combined with the optical signal in the receiving path through an optical circulator. After amplitude and delay matching is achieved through an adjustable optical attenuator and an adjustable delay line, the signal is obtained. Together they enter the photodetector beat frequency, the expression of which is: in, and These are the amplitudes of the interference signal and the reference signal, respectively. The delay introduced by the adjustable delay line is due to the fact that the reference signal and the interference signal originate from the same source. By matching amplitude and delay, i.e. ,and At this point, the reference signal and the interference signal coherently cancel each other out, thus achieving radio frequency self-interference cancellation.
8. A photon-assisted radio frequency cancellation device with a large instantaneous bandwidth, characterized in that, The photon-assisted radio frequency cancellation device performs radio frequency cancellation using the method described in any one of claims 1 to 7. The photon-assisted radio frequency cancellation device includes: Lasers, optical beam splitters, intensity modulator 1, intensity modulator 2, dual-drive modulators, adjustable delay lines, highly nonlinear optical fibers, dispersion-compensating optical fibers, circulators, optical amplifiers, adjustable attenuators, optical combiners, and photodetectors. The output port of the laser is connected to the optical input port of the optical beam splitter, and the three optical output ports of the optical beam splitter are respectively connected to the optical input ports of intensity modulator 1, dual-drive modulator and intensity modulator 2; The output port of intensity modulator 1 is connected to the optical input port of adjustable delay line, and the optical output port of adjustable delay line is connected to one input port of optical combiner to form a receiving path; The optical input port of the dual-drive modulator is connected to the left end of the highly nonlinear fiber, the right end of the highly nonlinear fiber is connected to the left end of the dispersion compensation fiber, and the right end of the dispersion compensation fiber is connected to the second interface of the circulator to form a reference path. The output port of intensity modulator 2 is connected to the optical input port of optical amplifier, and the optical output port of optical amplifier is connected to the first interface of circulator, forming a pump path; The third interface of the circulator is connected to the optical input port of the adjustable attenuator, the optical output port of the adjustable attenuator is connected to one input port of the optical combiner, and the optical output port of the optical combiner is connected to the optical input port of the photodetector.
9. The photon-assisted radio frequency cancellation device as described in claim 8, characterized in that, The laser is used to provide a narrow linewidth optical carrier as a seed light source, and the optical beam splitter is used to split one optical carrier into three branches. The intensity modulator 1 is used to modulate the received broadband signal onto the optical carrier, and the adjustable delay line is used to adjust the relative delay between the signal path and the reference path. The dual-drive modulator is used to modulate the reference signal onto the optical carrier, the highly nonlinear fiber is used to generate the stimulated Brillouin effect, and the dispersion compensation fiber is used to compensate for the dispersion introduced by the highly nonlinear fiber. The intensity modulator 1 is used to generate a two-tone optical carrier, and the optical amplifier is used to increase the power of the two-tone optical carrier to above the threshold of stimulated Brillouin scattering. The circulator is used for directional transmission of optical signals, the adjustable attenuator is used to adjust the relative power between the signal path and the reference path, and the photodetector is used to convert the optical signal into an electrical signal.
10. The photon-assisted radio frequency cancellation device as described in claim 9, characterized in that, The intensity modulator 1 is biased at the linear transmission point to achieve double-sideband modulation; The driving radio frequency signals applied to the upper and lower arms of the dual-drive modulator have a 90-degree phase difference and are biased at the linear transmission point to achieve single-sideband modulation, thereby changing the phase of the electrical signal after beat frequency by changing the phase of the optical carrier. The intensity modulator 2 is biased at the minimum transmission point to suppress the generation of dual-tone optical carriers by double-sideband modulation. By controlling the power and frequency of the dual-tone optical carriers, the phase of the reference optical signal carrier is modulated. The power of the dual-tone optical carriers can be adjusted by an optical amplifier, and the frequency of the dual-tone optical carriers is controlled by the driving frequency of the intensity modulator 2. The dispersion-compensating fiber and the highly nonlinear fiber introduce the same numerical value of dispersion, but with opposite signs.