Delay compensation device and method for simultaneously inhibiting dispersion and nonlinear effect

Abstract

The invention discloses a delay compensation device and method for simultaneously suppressing dispersion and nonlinear effect, a laser is connected with a first sub-modulator and a second sub-modulator of a first double-parallel modulator, and the first sub-modulator and the second sub-modulator of the first double-parallel modulator are both connected with a first optical circulator; a first sub-modulator of the first dual-parallel modulator loads a radio frequency signal; the first optical circulator is connected with the second optical circulator through the delay switching module, the first optical circulator outputs radio frequency signals through the photoelectric detector and the radio frequency filter, the second optical circulator is connected with the optical filter through the second double-parallel modulator, and the optical filter is connected with the second optical circulator through the optical amplifier. A first sub-modulator of the second dual-parallel modulator loads a local oscillator signal; the second double-parallel modulator performs blue shift on a return optical signal in the back-and-forth optical fiber link; the method has the advantages that the requirement for miniaturization of equipment is met while the nonlinear effect is suppressed.

Description

Technical Field

[0001] The present invention relates to the field of microwave technology, and in particular to a delay compensation device and method for simultaneously suppressing dispersion and nonlinear effects. Background Art

[0002] Delay calibration equipment is mainly used to simulate the delayed echo signal of the detected target to achieve self-test and calibration of the entire system including the antenna array, transceiver link, etc., and is widely used in communications, radar, satellite navigation and other fields. Traditional electronic delay calibration usually requires high-precision digital acquisition equipment, which is expensive, complex in structure, large in size, and has high manufacturing and maintenance costs. In addition, the stability of the equipment is easily affected in complex electromagnetic environments or extreme climates. In addition, as the system bandwidth increases, there are bandwidth limitations in high-frequency signal processing, which makes it difficult to meet the application requirements of high-speed electronic systems. Fiber optic delay calibration equipment has natural advantages such as low loss, broadband, and resistance to electromagnetic interference. It mainly uses the method of simulating true delay to achieve signal delay. The system has low cost, low power consumption, and is easy to use. It has been widely used in optical communications, satellite navigation, radar and other fields.

[0003] However, the development of electronic systems such as miniaturized radars and drone-mounted radars has placed higher demands on the system size of delay calibration equipment. While miniaturization is required, the dispersion and nonlinear effects in optical fibers can cause severe distortion of broadband signal waveforms in large delay calibration scenarios. Therefore, it is necessary to propose a method and design for miniaturized optical fiber delay calibration equipment that can suppress the dispersion and nonlinear effects in the link while ensuring high-performance signal delay. Chinese Patent Publication No. CN115441951A discloses a device and method for suppressing periodic fading in microwave photonic link transmission, which can effectively suppress dispersion effects but cannot suppress nonlinear effects or achieve miniaturization. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the delay compensation method in the prior art cannot suppress the nonlinear effect of the optical fiber link and cannot meet the miniaturization requirements of the equipment.

[0005] The present invention solves the above technical problems through the following technical means: a delay compensation device that simultaneously suppresses dispersion and nonlinear effects, including a laser, a first dual parallel modulator, a second dual parallel modulator, a first optical circulator, a second optical circulator, a delay switching module, a photodetector, an optical filter, an optical amplifier, and a radio frequency filter. The first dual parallel modulator and the second dual parallel modulator both include first to third sub-modulators, the third sub-modulator controls the phase offset of the optical carrier signal output by the second sub-modulator relative to the output signal of the first sub-modulator, and the laser is connected to the first sub-modulator and the third sub-modulator of the first dual parallel modulator. The first sub-modulator and the second sub-modulator of the first dual parallel modulator are connected to the first optical circulator, and the first sub-modulator of the first dual parallel modulator is loaded with a radio frequency signal; the first optical circulator is connected to the second optical circulator through a delay switching module, and the first optical circulator also outputs a radio frequency signal through a photodetector and a radio frequency filter; the second optical circulator is connected to the optical filter through the second dual parallel modulator, and the optical filter is connected to the second optical circulator through an optical amplifier, and the first sub-modulator of the second dual parallel modulator is loaded with a local oscillator signal; the second dual parallel modulator blue-shifts the return optical signal in the round-trip optical fiber link.

[0006] Furthermore, the delay switching module is implemented by cascading multiple optical switches and optical fibers of different lengths.

[0007] Furthermore, the second dual parallel modulator blue-shifts the return optical signal in the round-trip optical fiber link, including:

[0008] The frequency of the local oscillator signal of the second dual parallel modulator is greater than twice the highest frequency of the transmitted radio frequency signal.

[0009] The present invention further provides a delay compensation method for simultaneously suppressing dispersion and nonlinear effects, using the above-mentioned delay compensation device for simultaneously suppressing dispersion and nonlinear effects, the method comprising:

[0010] The laser transmits the signal to the second dual parallel modulator via the second dual parallel modulator, the first optical circulator, the delay switching module and the second optical circulator. The optical signal output after modulation by the second dual parallel modulator is filtered by an optical filter. The passband of the optical filter only allows the upper sideband signal modulated by the second dual parallel modulator to pass through. After being amplified by the optical amplifier, the signal is then reversely input into the transmission optical fiber of the delay switching module after passing through the second optical circulator for transmission, and then output through the first optical circulator and realize photoelectric conversion after passing through the detector.

[0011] Furthermore, the delay compensation method for simultaneously suppressing dispersion and nonlinear effects further includes:

[0012] The optical signal input to the photodetector includes the stimulated Brillouin backscattering signal f s As well as the blue-shifted modulated signal, the RF signal output after the beat frequency is then filtered out of the band by the RF filter to remove the out-of-band spurious signals, and finally achieve RF output with a delay of twice the length of the optical fiber.

[0013] Furthermore, the laser transmits the signal to the second dual parallel modulator via the second dual parallel modulator, the first optical circulator, the delay switching module and the second optical circulator, including:

[0014] The laser outputs an optical carrier signal, which is input into the first dual parallel modulator and modulated by the transmission delayed RF signal on the first sub-modulator of the first dual parallel modulator. By adjusting the bias voltage V 11 , ensuring that it works in the carrier suppressed double sideband modulation state; the RF input end of the second sub-modulator of the first dual parallel modulator is not loaded with RF signal, and its bias voltage V is adjusted 12 Ensure that the output optical carrier signal is maximized; the bias voltage V 13 Control the phase offset of the optical carrier signal output by the second sub-modulator relative to the output signal of the first sub-modulator; the optical signal output by the first dual parallel modulator after modulation is input into the transmission optical fiber of the delay switching module after passing through the first optical circulator for transmission, and then input into the second dual parallel modulator after passing through the second optical circulator.

[0015] Furthermore, the modulation process of the second dual parallel modulator is:

[0016] The local oscillator signal is input to the first sub-modulator of the second dual parallel modulator and controls the bias voltage V of the first sub-modulator of the second dual parallel modulator. 21 The first sub-modulator operates in the carrier suppressed double-sideband modulation state, the RF input end of the second sub-modulator of the second dual parallel modulator is not loaded with RF signal, and the bias voltage V 22 Maximize the optical carrier signal output by the second sub-modulator; the bias voltage V 23 The phase shift of the optical carrier signal output by the second sub-modulator relative to the output signal of the first sub-modulator is controlled.

[0017] Furthermore, the delay compensation method for simultaneously suppressing dispersion and nonlinear effects further includes a dispersion suppression process, which includes:

[0018] The phase difference between the optical carrier signal and the modulation sideband is adjusted by controlling the corresponding third sub-modulators in the first dual parallel modulator and the second dual parallel modulator respectively, thereby eliminating the periodic fading caused by the dispersion effect.

[0019] Furthermore, the dispersion suppression process further includes:

[0020] The power P of the RF signal output by the photodetector o Expressed as

[0021]

[0022] Where ∝ is a proportional symbol, D represents the dispersion coefficient of the optical fiber, λ represents the wavelength of the transmitted optical signal, and f m represents the frequency of the input RF signal, L represents the transmission distance, and c represents the propagation speed of the optical signal in a vacuum. Indicates the phase offset between the optical carrier and the modulated sideband.

[0023] Furthermore, the dispersion suppression process further includes:

[0024] f m , D, λ and c are all fixed, and only need to be adjusted according to the change of the transmission distance L of the modulated optical signal by controlling the corresponding third sub-modulator in the first double parallel modulator and the second double parallel modulator respectively. changes, making Ensure that the power of the output RF signal is independent of the transmission distance, thereby suppressing the dispersion effect.

[0025] The advantages of the present invention are:

[0026] (1) The optical carrier signal output by the laser of the present invention is forward transmitted to the second dual parallel modulator through the transmission optical fiber of the delay switching module. The optical signal output by the second dual parallel modulator after modulation passes through an optical filter, an optical amplifier, and a second optical circulator and is reversely input into the transmission optical fiber of the delay switching module for transmission, thereby reducing the optical fiber length by half by using a round-trip optical fiber link, thereby significantly reducing the volume and size of the system and meeting the miniaturization requirements of the equipment. At the same time, in order to solve the problem that the stimulated Brillouin scattered light signal in the round-trip optical fiber transmission link will overlap with the system output signal and introduce in-band stray light, the photon frequency shifting technology is used to blue-shift the return optical signal, thereby avoiding the stimulated Brillouin backscattered light generated by the forward transmission and the stray light output by the return output optical signal at the beat frequency of the detector being outside the signal bandwidth, thereby eliminating the influence of nonlinear effects on the in-band transmission signal.

[0027] (2) The present invention also addresses the phenomenon that the transmission signal exhibits periodic fading due to the dispersion effect in long-distance transmission links. A dual parallel modulator is used to preset the phase difference between the carrier signal and the modulated sideband signal to eliminate the periodic fading caused by the dispersion effect, thereby achieving miniaturized, long-distance, high-performance delay calibration as a whole. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic structural diagram of a delay compensation device for simultaneously suppressing dispersion and nonlinear effects disclosed in an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the spectrum shape at each node in a delay compensation device for simultaneously suppressing dispersion and nonlinear effects disclosed in an embodiment of the present invention, wherein: Figure 2 (a) is the result after modulation by the first dual parallel modulator, Figure 2 (b) is the result after modulation by the second dual parallel modulator, Figure 2 (c) is the optical signal input to the photodetector. DETAILED DESCRIPTION

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0031] like Figure 1As shown, the present invention provides a delay compensation device that suppresses dispersion and nonlinear effects simultaneously, comprising a laser 1, a first dual parallel modulator 2, a first optical circulator 3, a delay switching module 4, a second optical circulator 5, a second dual parallel modulator 6, an optical filter 7, an optical amplifier 8, a photodetector 9, and a radio frequency filter 10. The first dual parallel modulator 2 and the second dual parallel modulator 6 each include a first sub-modulator to a third sub-modulator, the third sub-modulator controls the phase shift of the optical carrier signal output by the second sub-modulator relative to the phase shift of the optical carrier signal output by the first sub-modulator. The laser 1 is connected to the first sub-modulator and the second sub-modulator of the first dual parallel modulator 2. Then, the first submodulator and the second submodulator of the first dual parallel modulator 2 are both connected to the first optical circulator 3. The first submodulator of the first dual parallel modulator 2 is loaded with an RF signal, while the second submodulator of the first dual parallel modulator 2 is not loaded with an RF signal. The first optical circulator 3 is connected to the second optical circulator 5 via the delay switching module 4. The first optical circulator 3 also outputs an RF signal through a photodetector 9 and an RF filter 10. The second optical circulator 5 is connected to an optical filter 7 via a second dual parallel modulator 6. The optical filter 7 is connected to the second optical circulator 5 via an optical amplifier 8. The first submodulator of the second dual parallel modulator 6 is loaded with a local oscillator signal. The following details the process and principle of a delay compensation method that simultaneously suppresses dispersion and nonlinear effects.

[0032] Continue reading Figure 1 , the laser 1 outputs the optical carrier signal, which is input into the first dual parallel modulator 2, and the delayed RF signal f rf , whose working bandwidth is B, modulated on the first sub-modulator of the first dual parallel modulator 2, by adjusting the bias voltage V of the first sub-modulator of the first dual parallel modulator 2 11 , ensuring that it works in carrier suppressed double sideband modulation state.

[0033] like Figure 2 As shown, the RF input terminal of the second sub-modulator of the first dual parallel modulator 2 is not loaded with RF signal, and its bias voltage V is adjusted. 12 The bias voltage V of the third sub-modulator of the first dual parallel modulator 2 is ensured to be the maximum. 13 The optical carrier signal output by the second sub-modulator is controlled to shift in phase relative to the output signal of the first sub-modulator, and its spectrum shape is as follows: Figure 2 As shown in (a), the first sub-modulator of the first dual parallel modulator 2 receives the optical carrier signal and modulates it with the RF signal. The optical carrier signal is suppressed and ±1-order modulated sideband signals are generated on both sides of the optical carrier signal. The RF input end of the second sub-modulator of the first dual parallel modulator 2 is not loaded with the RF signal, so it directly receives the optical carrier signal and outputs the optical carrier signal. However, due to the bias voltage V13 There is a certain phase offset between the optical carrier signal output by the second sub-modulator of the first dual parallel modulator 2 and the ±1-order sideband signals output by the first sub-modulator of the first dual parallel modulator 2, and the optical carrier signal is much larger than the ±1-order sideband signals.

[0034] The optical signal output after modulation by the aforementioned first dual parallel modulator 2 passes through the first optical circulator 3 and is input into the transmission optical fiber for long-distance transmission. A delay switching module 4 is integrated in the transmission optical fiber link, which can switch the length of the optical fiber link according to actual application needs. The delay switching module 4 can be realized by cascading multiple optical switches with optical fibers of different lengths. During the forward transmission process, the modulated optical signal will generate a stimulated Brillouin optical signal due to the nonlinear effect of the optical fiber. Since the optical carrier signal is absolutely dominant in the transmitted optical signal and the sideband optical signal is very small, only the stimulated Brillouin reflection signal of the optical carrier signal is considered here, and the stimulated Brillouin optical signal generated by the ±1-order sideband signal is not considered. The stimulated Brillouin reflection signal of the optical carrier signal is transmitted in the reverse direction along the optical fiber, and its frequency is the frequency blue-shifted Brillouin frequency shift of the forward transmitted optical carrier signal, which is as follows: Figure 2 (b) f s .

[0035] The optical signal after optical fiber transmission is outputted by the second optical circulator 5 and inputted into the second dual parallel modulator 6. The local oscillator signal is inputted into the first sub-modulator of the second dual parallel modulator 6 and the bias voltage V 21 The second sub-modulator of the second dual parallel modulator 6 does not load the RF signal, and its bias voltage V 22 The bias voltage V of the third sub-modulator of the second dual parallel modulator 6 is ensured to be the maximum output of the optical carrier signal. 23 The phase shift of the optical carrier signal output by the second sub-modulator relative to the output signal of the first sub-modulator is controlled.

[0036] The frequency f of the local oscillator signal loaded on the second dual parallel modulator 6 is LO It must be at least twice the highest frequency of the transmitted RF signal to ensure that the subsequent optical filter 7 can filter it. To further ensure a better signal-to-noise ratio, the frequency of the local oscillator signal must be at least three times the highest frequency of the transmitted RF signal. The spectrum shape of the optical signal in the optical fiber after modulation by the second dual parallel modulator 6 is as follows: Figure 2 As shown in (b), the second dual-parallel modulator 6 generates ±1-order integrally modulated sideband signals on both sides of the forward transmitted optical signal. The ±1-order integrally modulated sideband signals include complete optical information, such as the optical carrier signal generated by the first dual-parallel modulator 2 and its ±1-order sideband signals.

[0037] The optical signal modulated by the second dual-parallel modulator 6 is filtered by an optical filter 7. The passband of the optical filter 7 allows only the entire sideband signal modulated by the second dual-parallel modulator 6 to pass through. Here, taking the passage of the sideband signal as an example, the signal is amplified by an optical amplifier 8 and then passed through the second optical circulator 5 before being input back into the transmission fiber for long-distance transmission. After transmission through the same length of optical fiber, it is output through the first optical circulator 3 and then passes through a detector for photoelectric conversion.

[0038] The optical signal input to the photodetector 9 has a spectrum shape as follows: Figure 2 As shown in (c), it includes the stimulated Brillouin backscattering signal of the optical fiber forward transmission and the upper sideband overall signal. At this time, the frequency interval between the stimulated Brillouin backscattering signal and the upper sideband overall signal is greater than the frequency f of the local oscillator signal. LO , since the frequency f of the local oscillator signal mentioned above LO It must be at least twice the highest frequency of the transmitted RF signal. Therefore, the spurious signal generated by the stimulated Brillouin backscattering signal after the photoelectric conversion beat frequency is not within the working bandwidth of the transmitted RF signal. The output RF signal can filter out the out-of-band spurious signals after passing through the RF filter 10 to ensure the purity of the signal, and finally achieve RF output with a delay of twice the length of the optical fiber.

[0039] The aforementioned dispersion effect during transmission in long-distance optical fibers can cause periodic fading in the RF signal output by the detector after transmission. The device designed in the present invention not only suppresses the influence of the stimulated Brillouin signal on the output signal, but also facilitates the combination of dual parallel modulators to simultaneously suppress the dispersion effect. For optical signals of different frequencies, after propagating the same distance in the optical fiber, their phase changes differ, i.e., θ(ω) = β(ω)L. Here, θ is the induced phase difference, L is the transmission distance, and β is the propagation constant for the corresponding frequency.

[0040] The frequency dependence of β(ω) within the signal bandwidth can be expressed using the Taylor expansion at the optical carrier frequency:

[0041]

[0042] Among them, ω and ω0 are the corresponding optical frequency and the angular frequency of the optical carrier, β0 is the propagation constant of the optical carrier at ω0, β1 and β2 are its first and second order differentials, respectively, which can be obtained by Calculate, and ignore other high-order terms.

[0043] For the input RF signal, its angular frequency is ω mAfter double-sideband modulation, the upper and lower sidebands and the optical carrier signal enter the photodetector 9 at the same time. The upper and lower sidebands beat with the optical carrier respectively, generating a current intensity proportional to the power of the optical signal. Ignoring the DC and high-order terms of the current, the first-order current i + The first-order current i outputted by the lower sideband and the carrier beat frequency can be expressed as:

[0044]

[0045] Therefore, the current i0 after the beat frequency signals of the upper and lower sidebands are superimposed can be expressed as:

[0046]

[0047] From the above formula, we can see that the amplitude of the output signal is related to L, that is, it is related to the transmission distance. The power P of the RF signal output by the detector is o , which is proportional to the square of the output current, that is:

[0048]

[0049] The dispersion coefficient of the optical fiber Where λ is the wavelength of the transmitted light signal, and c is the propagation speed of the light signal in a vacuum. Substituting this into the above formula yields:

[0050]

[0051] where f m is the frequency of the input RF signal. As can be seen from the above formula, due to the existence of dispersion effect, the output RF signal power changes periodically as the transmission distance L increases.

[0052] When the phase difference between the optical carrier and the modulation sideband is adjusted by controlling the third sub-modulator in the first bi-parallel modulator 2 and the second bi-parallel modulator 6, the corresponding phase offset is introduced. After that, for the upper sideband, the beat frequency output current signal i + Changes to:

[0053]

[0054] For the lower sideband, the beat frequency output current signal i changes to:

[0055]

[0056] Therefore, the current i0 after the beat frequency signals of the upper and lower sidebands are superimposed can be expressed as:

[0057]

[0058] Then the detector outputs the power of the RF signal P o It can be expressed as:

[0059]

[0060] It can be seen from the above formula that for the actual application system, the frequency f of the transmitted RF signal is m The dispersion coefficient D of the selected optical fiber and the wavelength λ of the optical carrier are fixed. It is only necessary to adjust the distance L of the modulated optical signal propagation to change the value of the optical fiber. changes, making This ensures that the power of the output RF signal is independent of the transmission distance, thereby suppressing periodic fading. By controlling the bias voltage V of the third sub-modulator in the two dual parallel modulators according to the length of the transmission fiber, 13 and V 23 Adjust the phase difference between the optical carrier and the modulation sideband to compensate for the dispersion effect and eliminate the periodic fading of the output signal.

[0061] Through the above technical solution, in response to the current demand for miniaturization of delay calibration equipment and suppression of dispersion and nonlinear effects in long-distance delay optical fibers, the present invention proposes a delay calibration method and device that simultaneously suppresses dispersion and nonlinear effects. For long-distance optical fiber delay, a round-trip optical fiber link is used to reduce the optical fiber length by half, thereby significantly reducing the volume and size of the system. At the same time, in response to the problem that the stimulated Brillouin scattered light signal in the round-trip optical fiber transmission link will overlap with the system output signal and introduce in-band stray light, the photon frequency shifting technology is used to blue-shift the return optical signal to avoid the stray light generated by the stimulated Brillouin backscattered light generated by the forward transmission and the return output optical signal at the detector beat frequency output being outside the signal bandwidth, thereby eliminating the impact of nonlinear effects on the in-band transmission signal. At the same time, in response to the phenomenon that the dispersion effect in the long-distance transmission link causes the transmission signal to exhibit periodic fading, a dual parallel modulator is used to preset the phase difference between the carrier signal and the modulated sideband signal to eliminate the periodic fading caused by the dispersion effect, thereby achieving miniaturized, long-distance, and high-performance delay calibration.

[0062] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A delay compensation device that simultaneously suppresses dispersion and nonlinear effects, characterized in that: The invention comprises a laser, a first dual parallel modulator, a second dual parallel modulator, a first optical circulator, a second optical circulator, a delay switching module, a photodetector, an optical filter, an optical amplifier and a radio frequency filter. The first dual parallel modulator and the second dual parallel modulator both comprise first to third sub-modulators. The third sub-modulator controls the phase offset of the optical carrier signal output by the second sub-modulator relative to the output signal of the first sub-modulator. The laser is connected to the first sub-modulator and the second sub-modulator of the first dual parallel modulator. The first sub-modulator and the second sub-modulator of the first dual parallel modulator are both connected to the first optical circulator. The first sub-modulator of the first dual parallel modulator is loaded with a radio frequency signal. The first optical circulator is connected to the second optical circulator via the delay switching module. The first optical circulator also outputs a radio frequency signal through the photodetector and the radio frequency filter. The second optical circulator is connected to the optical filter via the second dual parallel modulator. The optical filter is connected to the second optical circulator via the optical amplifier. The first sub-modulator of the second dual parallel modulator is loaded with a local oscillator signal. The second dual parallel modulator blue-shifts the return optical signal in the optical fiber link.

2. The delay compensation device for simultaneously suppressing dispersion and nonlinear effects according to claim 1, characterized in that: The delay switching module is realized by cascading multiple optical switches and optical fibers of different lengths.

3. The delay compensation device for simultaneously suppressing dispersion and nonlinear effects according to claim 1, characterized in that: The second dual parallel modulator blue-shifts the return optical signal in the optical fiber link, including: The frequency of the local oscillator signal of the second dual parallel modulator is greater than twice the highest frequency of the transmitted radio frequency signal.

4. A delay compensation method for simultaneously suppressing dispersion and nonlinear effects, characterized in that: A method for applying the delay compensation device for simultaneously suppressing dispersion and nonlinear effects according to any one of claims 1 to 3, wherein the method comprises: The laser transmits the signal to the second dual parallel modulator via the second dual parallel modulator, the first optical circulator, the delay switching module and the second optical circulator. The optical signal output after modulation by the second dual parallel modulator is filtered by an optical filter. The passband of the optical filter only allows the upper sideband signal modulated by the second dual parallel modulator to pass through. After being amplified by the optical amplifier, the signal is then reversely input into the transmission optical fiber of the delay switching module after passing through the second optical circulator for transmission, and then output through the first optical circulator and realize photoelectric conversion after passing through the detector.

5. The delay compensation method for simultaneously suppressing dispersion and nonlinear effects according to claim 4, characterized in that: Also includes: The optical signal input to the photodetector includes the stimulated Brillouin backscattering signal f s As well as the blue-shifted modulated signal, the RF signal output after the beat frequency is then filtered out of the band by the RF filter to remove the out-of-band spurious signals, and finally achieve RF output with a delay of twice the length of the optical fiber.

6. The delay compensation method for simultaneously suppressing dispersion and nonlinear effects according to claim 4, characterized in that: The laser transmits the signal to the second dual parallel modulator via the second dual parallel modulator, the first optical circulator, the delay switching module and the second optical circulator, including: The laser outputs an optical carrier signal, which is input into the first dual parallel modulator and modulated by the transmission delayed RF signal on the first sub-modulator of the first dual parallel modulator. By adjusting the bias voltage V 11 , ensuring that it works in the carrier suppressed double sideband modulation state; the RF input end of the second sub-modulator of the first dual parallel modulator is not loaded with RF signal, and its bias voltage V is adjusted 12 Ensure that the output optical carrier signal is maximized; the bias voltage V 13 Control the phase offset of the optical carrier signal output by the second sub-modulator relative to the output signal of the first sub-modulator; the optical signal output by the first dual parallel modulator after modulation is input into the transmission optical fiber of the delay switching module after passing through the first optical circulator for transmission, and then input into the second dual parallel modulator after passing through the second optical circulator.

7. The delay compensation method for simultaneously suppressing dispersion and nonlinear effects according to claim 6, characterized in that: The modulation process of the second dual parallel modulator is: The local oscillator signal is input to the first sub-modulator of the second dual parallel modulator and controls the bias voltage V of the first sub-modulator of the second dual parallel modulator. 21 The first sub-modulator operates in the carrier suppressed double-sideband modulation state, the RF input end of the second sub-modulator of the second dual parallel modulator is not loaded with RF signal, and the bias voltage V 22 Maximize the optical carrier signal output by the second sub-modulator; the bias voltage V 23 The phase shift of the optical carrier signal output by the second sub-modulator relative to the output signal of the first sub-modulator is controlled.

8. The delay compensation method for simultaneously suppressing dispersion and nonlinear effects according to claim 4, characterized in that: The dispersion suppression process is further included, and the dispersion suppression process includes: The phase difference between the optical carrier signal and the modulation sideband is adjusted by controlling the corresponding third sub-modulators in the first dual parallel modulator and the second dual parallel modulator respectively, thereby eliminating the periodic fading caused by the dispersion effect.

9. The delay compensation method for simultaneously suppressing dispersion and nonlinear effects according to claim 8, characterized in that: The dispersion suppression process further includes: The power P of the RF signal output by the photodetector o Expressed as Where ∝ is a proportional symbol, D represents the dispersion coefficient of the optical fiber, λ represents the wavelength of the transmitted optical signal, and f m represents the frequency of the input RF signal, L represents the transmission distance, and c represents the propagation speed of the optical signal in a vacuum. Indicates the phase offset between the optical carrier and the modulated sideband.

10. The delay compensation method for simultaneously suppressing dispersion and nonlinear effects according to claim 9, characterized in that: The dispersion suppression process further includes: f m , D, λ and c are fixed, and are adjusted according to the change of the transmission distance L of the modulated optical signal by controlling the corresponding third sub-modulator in the first double parallel modulator and the second double parallel modulator respectively. changes, making Ensure that the power of the output RF signal is independent of the transmission distance, thereby suppressing the dispersion effect.

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