Broadband instantaneous frequency measurement receiving system based on Brillouin spectrum compression

Abstract

The invention relates to the field of signal frequency detection in microwave photonics, and discloses a broadband instantaneous frequency measurement receiving system based on Brillouin spectrum compression, which utilizes a dual-tone pump optical carrier signal carried on an intensity modulator and an optical filter to generate a single Brillouin pump source regulated and controlled by unknown radio frequency. A stimulated Brillouin structure narrowed by an optical fiber ring cavity and a single-pumping reference source subjected to phase shift beat frequency, a signal in a 45GHz range can be compressed to a bandwidth of 2.5 MHz, and meanwhile, an original signal can be subjected to optical domain down-conversion processing by a reference source signal, so that a low-frequency signal easy to process electronically is obtained; besides, a double-fiber annular cavity design is adopted, the line width of the Brillouin resonant laser is further compressed through mode matching of interference of light waves in the cavity, test precision reduction caused by frequency spectrum compression is made up, the resolution ratio can reach + / -2.2 MHz, and finally the Brillouin broadband instantaneous frequency measurement receiving technology is achieved.

Description

Technical Field

[0001] This invention relates to the field of frequency detection in microwave photonics, specifically a broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression. Background Technology

[0002] Traditional techniques such as electronic counters and Fourier transform spectroscopy can measure frequencies, but their high-frequency parasitic effects on electronic components limit their ability to achieve high-speed testing over a wide bandwidth. Microwave photonics-based frequency measurement techniques, however, offer significant advantages in real-time tracking and high-speed analysis of complex modulated signals due to their low loss, wide bandwidth, and strong anti-interference capabilities. Among these, instantaneous frequency measurement based on the Brillouin effect has attracted widespread attention from scholars both domestically and internationally due to its ability to achieve high resolution over a wide bandwidth, showing great promise for applications in electronic warfare, electromagnetic spectrum competition, and radar detection. In 2017, Pan Linbing et al. from Jilin University measured frequencies from 0.5 GHz to 27 GHz using a pump-probe structure, achieving microwave resolution below 5 MHz. In 2019, Zou Weiwen et al. from Shanghai Jiao Tong University optimized the gain spectral response through pump light waveform modulation, achieving a frequency measurement scheme with a resolution of 100 MHz covering a spectrum exceeding 6 GHz in the Ku band. While these schemes achieved GHz bandwidth, achieving high-resolution instantaneous frequency measurement remains a significant challenge. H. Jiang et al. from the University of Sydney proposed a distributed Brillouin detection system. The designed frequency power function curve enables high-resolution measurements down to ±1MHz in the range of 9 to 38 GHz. Although it achieves extremely high resolution, it increases the complexity of the system and is limited by the Brillouin frequency shift, making it difficult to receive microwave signals across the entire frequency band.

[0003] Therefore, current Brillouin microwave photonic instantaneous frequency measurement systems cannot simultaneously meet the requirements of full-band bandwidth, high resolution, and simple structure. During frequency measurement, the range of the photodetector needs to match the measured microwave bandwidth, increasing the design cost of the frequency measurement receiver and extending the measurement time, making it difficult to meet the needs of practical applications. To solve these problems, this invention proposes a broadband instantaneous frequency measurement and reception technology based on Brillouin laser spectrum compression. Summary of the Invention

[0004] To address the issues of narrow bandwidth in current instantaneous frequency measurement systems and the complex structure and high-frequency detection requirements in Brillouin microwave photonics, this invention proposes a broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression. This system generates a single-tone pump-excited Brillouin signal by combining a fixed-frequency laser, an intensity modulator, and an optical filter. By combining a Brillouin dual-ring narrow-linewidth resonant cavity with a reference RF signal beat frequency mounted on a phase modulator, the system achieves instantaneous frequency measurement and receiving with a maximum resolution of ±2.2MHz, compressing signals within the 45GHz range to 2.5MHz.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression, comprising a single-tone pump light generation optical path, a Brillouin dual-ring narrow-linewidth resonant cavity optical path, and a reference signal beat frequency optical path; wherein, the single-tone pump light generation optical path generates the single-tone pump light required to excite the Brillouin; the Brillouin dual-ring narrow-linewidth resonant cavity optical path forms a cascaded cavity by a first ring cavity R1 and a second ring cavity R2, and adjusts the polarization direction of the pump light and Stokes light within the ring by adjusting the polarization controller within the cavity, thereby adjusting the coupling efficiency and stability of the stimulated Brillouin of the single-tone pump light, and finally outputting the Brillouin resonant laser; the reference signal beat frequency optical path uses the single-tone pump light as an optical carrier and obtains a single Brillouin pump source by phase modulation with a microwave signal, and realizes the beat frequency of the single Brillouin pump source and the Brillouin resonant laser.

[0006] The aforementioned broadband instantaneous frequency measurement and receiving system based on Brillouin spectral compression includes a single-tone pump light generation optical path comprising a fixed-frequency laser, a first erbium-doped fiber amplifier, a second erbium-doped fiber amplifier, a first polarization controller, an intensity modulator, a voltage source, an optical filter, and a first optical coupler; the fixed-frequency laser emits a center frequency of f. c The light, acting as a carrier wave, is amplified by the first erbium-doped fiber amplifier and then enters the first polarization controller to adjust its polarization state. It is then input to the first input port a of the intensity modulator, where the radio frequency signal f to be measured is located. m The voltage source is input through the second input port b of the intensity modulator, and carrier suppression is performed through the third input port c of the intensity modulator. The pump light supports a double-sideband modulation mode to achieve double-sideband gain, generating upper and lower sideband frequencies centered at f. c +f m and f c -f m The dual-tone pump light, after being filtered by an optical filter to remove the lower-frequency first-order sidebands, leaves f... c -f m The single-tone pump light is then amplified by a second erbium-doped fiber amplifier before entering the first input port a of the first optical coupler. In the first optical coupler, it is split into two paths: the Brillouin pump source is output from the first output port b, and the reference carrier signal is output from the second output port c.

[0007] The aforementioned broadband instantaneous frequency measurement and receiving system based on Brillouin spectral compression includes a Brillouin dual-ring narrow-linewidth resonant cavity optical path comprising a third polarization controller, a second optical coupler, a circulator, a first single-mode fiber, and a second single-mode fiber. The first single-mode fiber, the b port and c port of the circulator, the first input port a and second output port c of the second optical coupler, the second input port b and first output port c of the third optical coupler, and the third polarization controller together form a first ring cavity R1. The first input port a and second output port d of the third optical coupler together with the second single-mode fiber form a second ring cavity R2. The Brillouin pump source is input through the a port of the circulator, excited by the first single-mode fiber connected to the b port of the circulator, and output through the c port of the circulator, resonating in the first ring cavity R1. The stimulated Brillouin laser resonates counterclockwise along the first ring cavity R1 and is injected into the second ring cavity R2, where it resonates synchronously counterclockwise. Finally, the Brillouin resonant laser is output from the first output port b of the second optical coupler.

[0008] The aforementioned broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression includes a reference signal beat frequency optical path comprising a second polarization controller, a fourth optical coupler, a phase modulator, a signal generator, a spectrum analyzer, a photodetector, and a spectrum analyzer. The reference carrier signal is output through the second output port c of the optical coupler and then enters the third polarization controller to adjust its polarization state. Subsequently, it enters the first input port a of the phase modulator. The signal generator is connected to the second input port b of the phase modulator, with an input frequency approximately f. c The microwave signal with carrier Brillouin offset is modulated to obtain a single Brillouin pump source, which enters the first input port a of the fourth optical coupler. Together with the Brillouin resonant laser input from the second input port b of the fourth optical coupler, it is output from the first output port c of the fourth optical coupler and enters the spectrum analyzer. The signal is then input to the photodetector from the second output port d of the fourth optical coupler. After photoelectric conversion by the photodetector, the frequency signal is input to the spectrum analyzer. The measured frequency and amplitude are used to characterize the broadband instantaneous frequency measurement and reception technology of the proposed Brillouin spectrum compression.

[0009] In the aforementioned broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression, the first and second optical couplers have a splitting ratio of 90:10, port a is the input port, port b is the 90% output port, and port c is the 10% output port; the third and fourth optical couplers have a splitting ratio of 50:50.

[0010] In the aforementioned broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression, the first erbium-doped fiber amplifier has an input power range of -5 to 15 dBm and a maximum output power of 25 dBm; the second erbium-doped fiber amplifier has an input power range of -20 to 10 dBm and a maximum output power of 25 dBm.

[0011] The aforementioned broadband instantaneous frequency measurement and receiving system based on Brillouin spectral compression has a first single-mode fiber length of 500m and a second single-mode fiber length of 50m, with a free spectral range (FSR). ,in, Represents the speed of light. It is the effective refractive index during light propagation. Let m represent the length of the fiber optic ring cavity, where m = 1, 2 represents two fiber optic ring cavities R1 and R2, and the double rings satisfy the following conditions: , where n1 and n2 are integers, to satisfy the side-mode suppression of the Brillouin cavity resonance peak.

[0012] In the aforementioned broadband instantaneous frequency measurement and receiving system based on Brillouin spectral compression, the backward stimulated Brillouin laser frequency shift can be expressed by the following formula: ,in, The frequency shift of the Brillouin gain spectrum. It is the speed of sound in optical fiber. It is the frequency shift of the optical carrier; the unknown radio frequency signal to be tested is transferred to the frequency shift of the optical carrier by the intensity modulator, so as to realize the frequency detection of radio frequency signal based on the Brillouin frequency compression mechanism.

[0013] The aforementioned broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression can provide a physical quantity for characterizing the frequency of an unknown radio frequency signal by changing the single-sideband wavelength of the optical filter; compress the measurement range by a small change in the Brillouin gain spectrum with wavelength frequency shift; and change the measurement center frequency by changing the frequency of the microwave signal output by the signal generator.

[0014] Compared with existing technologies, this invention has the following advantages: Compared with existing instantaneous frequency measurement and reception technologies based on Brillouin scattering, the broadband instantaneous frequency measurement and reception technology based on Brillouin spectrum compression provided by this invention excites the Brillouin signal using a single-tone low-frequency pump signal, narrows the Brillouin gain spectral line using a vernier effect design based on a dual-ring fiber resonator, and beats the output frequency with the reference frequency-shifted signal, thereby realizing the transformation of Brillouin frequency measurement from the gigahertz level to the megahertz level, with a maximum resolution of ±2.2MHz output. This achieves a frequency measurement receiver design that is easy to detect, simple to design, and has high resolution over a broadband range. It can be applied to the design of broadband radio frequency signal identification systems in fields such as communication, detection, and military, and has significant market competitiveness. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the present invention.

[0016] Figure 2 The diagram shows the spectral radio frequency output power of the Brillouin spectrum compression broadband instantaneous frequency measurement and reception technology of the present invention, specifically the frequency measurement output signal, the single-tone pump signal used to excite the Brillouin, and the two-tone signal loaded onto the output of the intensity modulator.

[0017] Figure 3 This diagram illustrates the frequency measurement intervals on the spectrum for Brillouin compression frequencies of 15GHz, 30GHz, and 45GHz.

[0018] In the diagram: 1-Fixed frequency laser, 2A-First erbium-doped fiber amplifier, 2B-Second erbium-doped fiber amplifier, 3A-First polarization controller, 3B-Second polarization controller, 3C-Third polarization controller, 4-Intensity modulator, 5-Voltage source, 6-Optical filter, 7A-First optical coupler, 7B-Second optical coupler, 7C-Third optical coupler, 7D-Fourth optical coupler, 8-Optical circulator, 9A-First single-mode fiber, 9B-Second single-mode fiber, 10-Phase modulator, 11-Signal generator, 12-Spectrum analyzer, 13-Photodetector, 14-Spectrum analyzer, R1-First ring cavity, R2-Second ring cavity. Detailed Implementation

[0019] Specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0020] Combination Figure 1 As shown, the broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression of the present invention includes: a fixed frequency laser 1, a first erbium-doped fiber amplifier 2A, a second erbium-doped fiber amplifier 2B, a first polarization controller 3A, a second polarization controller 3B, a third polarization controller 3C, an intensity modulator 4, a voltage source 5, an optical filter 6, a first optical coupler 7A, a second optical coupler 7B, a third optical coupler 7C, a fourth optical coupler 7D, an optical circulator 8, a first single-mode fiber 9A, a second single-mode fiber 9B, a phase modulator 10, a signal generator 11, a spectrum analyzer 12, a photodetector 13, a spectrum analyzer 14, a first ring cavity R1, and a second ring cavity R2.

[0021] Based on the above-mentioned constituent elements, the constituent relationship of the present invention is as follows: the fixed frequency laser 1 emits a center frequency of f c Light at 1550.2 nm is used as the carrier wave. After being amplified to 20 dBm by the first erbium-doped fiber amplifier 2A, it enters the first input port a of the intensity modulator 4 through the first polarization controller 3A. The radio frequency signal to be measured, f, is then transmitted to the carrier wave. mA single-tone signal is input through the second input port b of the intensity modulator 4. The voltage source 5 performs carrier suppression through the third input port c of the intensity modulator 4. The pump light supports a double-sideband modulation mode to achieve double-sideband gain, generating upper and lower sideband frequencies centered at f. c +f m and f c -f m The dual-tone pump light is filtered out by optical filter 6 to remove the lower frequency first-order sideband. After being amplified to 25dBm by the second erbium-doped fiber amplifier 2B, it enters the first input port a of the first optical coupler 7A, where it is divided into a Brillouin pump source that outputs 90% of the single-tone pump power from the first output port b and a reference carrier signal that outputs 10% of the single-tone pump power from the second output port c.

[0022] The Brillouin pump source is input through port a of circulator 8, and port b of circulator 8 is connected to a 500m first single-mode fiber 9A for excitation into the Brillouin. The first ring cavity R1 is composed of the first single-mode fiber 9A, port b of circulator 8, port c of circulator 8, first input port a of second optical coupler 7B, second output port c with a 90% splitting ratio, second input port b of third optical coupler 7C, first output port c of third optical coupler 7C, and polarization controller 3C. The second ring cavity R2 is composed of the first input port a and second output port d of a 50:50 third optical coupler 7C and a 50m second single-mode fiber 9B. The stimulated Brillouin laser resonates counterclockwise along the first ring cavity R1 and is injected into the second ring cavity R2, where it resonates synchronously counterclockwise. The Brillouin resonant laser is output from the first output port b of the second optical coupler 7B. The relationship between the two resonant cavities is expressed by the following equation:

[0023] ;

[0024] Where n1 and n2 are integers, to satisfy the side-mode suppression of the Brillouin long cavity resonance peak, so that the Brillouin resonant laser with 10% power output from the first output port b of the second optical coupler 7B is narrowed. , The free spectral ranges of the first annular cavity R1 and the second annular cavity R2 are respectively expressed as:

[0025] ;

[0026] in, ≈3×10 8 m / s represents the speed of light. ≈1.45 is the effective refractive index for light propagation. The length of the fiber optic ring cavity is represented by m=1,2, and it represents two fiber optic ring cavities R1 and R2.

[0027] After the reference carrier signal is output through the second output port c of the first optocoupler 7A, it enters the third polarization controller 3B to adjust the polarization state, and then is input to the first input port a of the phase modulator 10. The signal generator 11 is connected to the second input port b of the phase modulator 10 and inputs a microwave signal with a frequency of 10.714 GHz, which enters the first input port a of the fourth optocoupler 7D. Together with the double-ring Brillouin resonant laser input through the second input port b of the fourth optocoupler 7D, it outputs 50% power from the first output port c of the fourth optocoupler 7D and enters the spectrum analyzer 12. The signal outputs 50% power from the second output port d of the fourth optocoupler 7D to the photodetector 13. After photoelectric conversion by the photodetector 13, the frequency signal is input to the spectrum analyzer 14.

[0028] refer to Figure 2 This is the spectral output result of a broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression as described in this invention. All spectra are test results when a 5GHz signal is applied to the intensity modulator. The frequency measurement output curve is measured at the first output port c of the fourth optical coupler 7D. The Brillouin curve excited by the single-tone signal is measured at the first output port b of the second optical coupler 7B, representing a Brillouin resonant laser with 10% output power; the peak frequency on the right is Stokes light. The two-tone signal is the direct output result of the first output port d of the intensity modulator 4; the pump frequency signal at 1550.2nm is voltage-suppressed, and the two sides are first-order sidebands at 5GHz modulated by unknown signals and gaining.

[0029] refer to Figure 3 The output spectrum of the broadband instantaneous frequency measurement and reception technique for Brillouin spectrum compression tested with a 15GHz standard signal in step shifts according to this invention is shown. The single-peak stimulated Brillouin frequency shift excited by this signal can be expressed by the following formula:

[0030] ;

[0031] in, The frequency shift of the Brillouin gain spectrum. ≈5800m / s is the speed of sound in optical fiber. This refers to the frequency shift of the optical carrier. The unknown radio frequency signal is transferred to the frequency shift of the optical carrier via intensity modulator 4, enabling radio frequency signal detection based on the Brillouin frequency compression mechanism at a center frequency of 100MHz. The scan time of the spectrum analyzer 14 is approximately 4ms, and the frequency compression factor is... Approximately 1.8 × 10 4The minimum linewidth monitored on the spectrum analyzer is approximately 120Hz, corresponding to a resolution of ±2.2MHz before spectrum compression. When shifted by 15GHz, the theoretical spectrum shift is approximately 841kHz. The Brillouin frequency compression spectrum shifts of 15GHz in the figure are 848kHz, 856kHz, and 844kHz, all close to the theoretical values. These errors are caused by discrepancies between the estimated and actual values ​​of the sound velocity and effective refractive index in the optical fiber. Therefore, the instantaneous frequency measurement device of this invention maintains MHz-level experimental accuracy while compressing the 45GHz signal testing range to 2.5MHz, reducing the requirements for electrical testing equipment.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments of the present invention, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the scope of the technical solutions of the present invention, and should all be covered within the protection scope of the claims of the present invention.

Claims

1. A broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression, characterized in that, The system includes a single-tone pump light generation optical path, a Brillouin double-ring narrow-linewidth resonant cavity optical path, and a reference signal beat frequency optical path. The single-tone pump light generation optical path generates the single-tone pump light required to excite the Brillouin. The Brillouin double-ring narrow-linewidth resonant cavity optical path is formed by a cascaded cavity consisting of a first ring cavity R1 and a second ring cavity R2. By adjusting the polarization direction of the pump light and Stokes light within the rings using a polarization controller, the coupling efficiency and stability of the stimulated Brillouin of the single-tone pump light are adjusted, ultimately outputting a Brillouin resonant laser. The reference signal beat frequency optical path uses the single-tone pump light as an optical carrier and modulates it with a microwave signal to obtain a single Brillouin pump source, achieving beat frequency between the single Brillouin pump source and the Brillouin resonant laser.

2. The broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression according to claim 1, characterized in that, The single-tone pump light generation optical path includes a fixed-frequency laser (1), a first erbium-doped fiber amplifier (2A), a second erbium-doped fiber amplifier (2B), a first polarization controller (3A), an intensity modulator (4), a voltage source (5), an optical filter (6), and a first optical coupler (7A); the fixed-frequency laser (1) emits a center frequency of f. c The light, acting as a carrier wave, is amplified by the first erbium-doped fiber amplifier (2A) and then enters the first polarization controller (3A) to adjust its polarization state. It is then input to the first input port a of the intensity modulator (4), where the radio frequency signal f to be measured is located. m The voltage source (5) is input through the second input port b of the intensity modulator (4), and the carrier is suppressed through the third input port c of the intensity modulator (4). The pump light supports the double-sideband modulation mode to achieve double-sideband gain, generating upper and lower sideband frequencies centered at f. c +f m and f c -f m The dual-tone pump light, after being filtered out by the optical filter (6) to remove the lower frequency first-order sideband, leaves f c -f m The single-tone pump light is then amplified by the second erbium-doped fiber amplifier (2B) and then enters the first input port a of the first optical coupler (7A). In the first optical coupler (7A), it is split into two paths, with the Brillouin pump source output from the first output port b and the reference carrier signal output from the second output port c.

3. The broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression according to claim 2, characterized in that, The Brillouin dual-ring narrow-linewidth resonant cavity optical path includes a third polarization controller (3C), a second optical coupler (7B), a circulator (8), a first single-mode fiber (9A), and a second single-mode fiber (9B). The first single-mode fiber (9A), the b port and c port of the circulator (8), the first input port a and the second output port c of the second optical coupler (7B), the second input port b and the first output port c of the third optical coupler (7C), together with the third polarization controller (3C), constitute the first ring cavity R1. The first input port a and the second output port c of the third optical coupler (7C) constitute the first ring cavity R1. The input port a, the second output port d, and the second single-mode fiber (9B) form the second ring cavity R2; the Brillouin pump source is input from port a of the circulator (8), and after being excited by the first single-mode fiber (9A) connected to port b of the circulator (8), it is directed to the Brillouin and output through port c of the circulator (8) to resonate in the first ring cavity R1; the stimulated Brillouin laser resonates in the counterclockwise direction along the first ring cavity R1 and is injected into the second ring cavity R2, and resonates synchronously in the counterclockwise direction in the second ring cavity R2, and finally outputs the Brillouin resonant laser from the first output port b of the second optical coupler (7B).

4. The broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression according to claim 3, characterized in that, The reference signal beat frequency optical path includes a second polarization controller (3B), a fourth optical coupler (7D), a phase modulator (10), a signal generator (11), a spectrum analyzer (12), a photodetector (13), and a spectrum analyzer (14). The reference carrier signal is output through the second output port c of the optical coupler (7A) and enters the third polarization controller (3B) to adjust the polarization state. Then it enters the first input port a of the phase modulator (10). The signal generator (11) is connected to the second input port b of the phase modulator (10) to input a microwave signal. The modulated single Brillouin pump source enters the first input port a of the fourth optical coupler (7D) and together with the Brillouin resonant laser input through the second input port b of the fourth optical coupler (7D), it is output through the first output port c of the fourth optical coupler (7D) and enters the spectrum analyzer (12). It is input through the second output port d of the fourth optical coupler (7D) to the photodetector (13). After photoelectric conversion by the photodetector (13), the frequency is input to the spectrum analyzer (14).

5. A broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression according to claim 4, characterized in that, The first optical coupler (7A) and the second optical coupler (7B) both have a splitting ratio of 90:10, with port a being the input port, port b being the 90% output port, and port c being the 10% output port; the third optical coupler (7C) and the fourth optical coupler (7D) both have a splitting ratio of 50:

50.

6. A broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression according to claim 2, 3, 4, or 5, characterized in that, The first erbium-doped fiber amplifier (2A) has an input power range of -5 to 15 dBm and a maximum output power of 25 dBm; the second erbium-doped fiber amplifier (2B) has an input power range of -20 to 10 dBm and a maximum output power of 25 dBm.

7. A broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression according to claim 3 or 4, characterized in that, The first single-mode fiber (9A) is 500m long; the second single-mode fiber (9B) is 50m long and has a free spectral range (FSR). ,in, Represents the speed of light. It is the effective refractive index during light propagation. Let m represent the length of the fiber optic ring cavity, where m = 1, 2 represents two fiber optic ring cavities R1 and R2, and the double rings satisfy the following conditions: , where n1 and n2 are integers, to satisfy the side-mode suppression of the Brillouin cavity resonance peak.

8. A broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression according to claim 3, 4, or 5, characterized in that, The aforementioned backward stimulated Brillouin laser frequency shift can be expressed by the following formula: ,in, The frequency shift of the Brillouin gain spectrum. It is the speed of sound in optical fiber. It is the frequency shift of the optical carrier; the unknown radio frequency signal to be tested is transferred to the frequency shift of the optical carrier by the intensity modulator (4), so as to realize the frequency detection of radio frequency signal based on the Brillouin frequency compression mechanism.

9. A broadband instantaneous frequency measurement and receiving system based on Brillouin spectrum compression according to claim 3, 4, or 5, characterized in that, The change in the single-sideband wavelength of the optical filter (6) can provide a physical quantity for characterizing the frequency of the unknown radio frequency signal under test; the compression of the measurement range can be achieved by the small change in the Brillouin gain spectrum with the wavelength frequency shift; the change of the measurement center frequency can be achieved by changing the frequency of the microwave signal output by the signal generator (11).

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