A stimulated Brillouin spectroscopy analysis device and method

Abstract

The present invention provides a stimulated Brillouin spectrum analysis device and method, the device includes an optical circulator, a stimulated Brillouin medium, a probe light source, a double-sideband IQ modulator, an optical isolator, a dense wavelength division multiplexer, an up-down frequency conversion detector and a data acquisition board, the light to be measured is injected into the stimulated Brillouin medium through the optical circulator, the probe light is modulated by the double-sideband IQ modulator and enters the stimulated Brillouin medium, the modulated probe light and the light to be measured generate characteristic frequency signals distributed on both sides of the probe light frequency based on the stimulated Brillouin effect, the optical signal collected by the up-down frequency conversion detector is demodulated, the stimulated Brillouin complex gain is calculated, and the information of the light to be measured is obtained by inversion. Through this solution, high-resolution spectrum analysis without scanning can be realized, the dependence on the Brillouin frequency offset in the optical fiber is eliminated, and the real-time performance of stimulated Brillouin spectrum analysis is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of spectrum analysis, and in particular relates to a stimulated Brillouin spectrum analysis device and method. Background Art

[0002] Spectral analysis is critical for a variety of applications such as optical communications, spectroscopy, sensing, and characterization of photonic devices. Although various implementation schemes have been proposed for spectral analysis technology, almost all of them require balancing spectral resolution, bandwidth, and acquisition time. For example, most short-wave infrared spectrometers rely on a scannable diffraction grating within the measurement range to measure one spectral channel at a time, which requires a trade-off between measurement time and the number of spectral channels collected. Similarly, most Fourier transform spectrometers also rely on scanning, resulting in slow acquisition time, and the sampling time increases as the spectral range measured increases. In addition, both methods are usually limited to spectral resolution in the GHz range.

[0003] In order to achieve higher resolution spectral analysis, we can use the narrowband SBS corresponding bandwidth of the optical fiber itself as the filter of the spectral system based on stimulated Brillouin scattering (SBS) to improve the spectral resolution. These spectral analysis methods require the use of a pump laser with a precisely known wavelength as a pump source, the use of the 10GHz frequency shift of the SBS itself to generate a frequency sideband signal, and then use coherent detection to extract the 30MHz bandwidth RF signal for analysis.

[0004] However, this method requires scanning the central wavelength of the pump laser to obtain a spectral resolution of about 30 MHz, and the acquisition time is limited by the scanning requirements. Usually, in order to detect weak spectral changes, it is necessary to rely on long-term coherent averaging to improve the contrast. Obviously, this spectral analysis method has poor real-time performance. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a stimulated Brillouin spectroscopy analysis device and method, which are used to solve the problem of poor real-time performance of current spectroscopy analysis methods.

[0006] In a first aspect of an embodiment of the present invention, a stimulated Brillouin spectroscopy analysis device is provided, comprising:

[0007] An optical circulator, used for injecting the light to be measured into the stimulated Brillouin medium;

[0008] Stimulated Brillouin medium, used to provide an optical medium for generating stimulated Brillouin effect, and to generate characteristic frequency signals distributed on both sides of the probe light frequency in the frequency domain;

[0009] A probe light source, used to provide a single-frequency laser to stimulate the stimulated Brillouin effect;

[0010] A double-sideband IQ modulator, used to generate frequency sidebands located on both sides of the probe light frequency through phase modulation, and perform frequency modulation according to the stimulated Brillouin frequency shift;

[0011] An optical isolator, used to maintain the direction of the single-frequency laser generated by the probe light source and isolate other light generated by the stimulated Brillouin effect;

[0012] A dense wavelength division multiplexer is used to separate the anti-Stokes light and the Stokes light located on both sides of the light to be measured and the probe light in the spectral line position;

[0013] Up and down conversion detectors, used to detect anti-Stokes light, Stokes light and corresponding local oscillator light signals respectively;

[0014] The data acquisition board is used to perform IQ demodulation according to the received optical signal, calculate the stimulated Brillouin complex gain, and obtain the optical information to be measured through inversion.

[0015] In a second aspect of an embodiment of the present invention, a stimulated Brillouin spectroscopy analysis method is provided, comprising:

[0016] The light to be measured is injected into the stimulated Brillouin medium through an optical circulator;

[0017] The single-frequency laser generated by the probe light source is modulated in a double-sideband IQ modulator, and frequency sidebands located on both sides of the probe light frequency are generated by phase modulation. The frequency is modulated according to the stimulated Brillouin frequency shift, and the modulated single-frequency laser is injected into the stimulated Brillouin medium through an optical isolator.

[0018] Based on the stimulated Brillouin effect, characteristic frequency signals distributed on both sides of the probe light frequency are generated in the frequency domain;

[0019] The anti-Stokes light and the Stokes light located on both sides of the light to be measured and the probe light at the spectral line position are received and separated by a dense wavelength division multiplexer, and the anti-Stokes light, the Stokes light and the corresponding local oscillator light signals are detected by an up-down frequency conversion detector;

[0020] IQ demodulation is performed according to the collected optical signal, the stimulated Brillouin complex gain is calculated, and the light information to be measured is obtained through inversion.

[0021] In the embodiment of the present invention, the frequency and phase changes of the light to be measured are accurately measured by pumping and detecting the Stokes light and anti-Stokes light generated by the interaction between the light to be measured and the stimulated Brillouin medium, decomposing the phase and amplitude information of the light to be measured into the probe light affected by the Brillouin effect, using the local oscillator light that does not participate in the stimulated Brillouin process, extracting the amplitude and phase information corresponding to the stimulated Brillouin effect, and then characterizing the frequency of the light to be measured by the nonlinear interaction frequency quantity. At the same time, the changes in Brillouin gain and phase are measured by IQ demodulation to reduce the influence of optical power fluctuations on the measurement, and the information of Stokes and anti-Stokes interactions is combined to eliminate the dependence on Brillouin frequency offset in the optical fiber, so that the measurement method is not affected by temperature fluctuations. Thereby, not only high-resolution spectral analysis without scanning is achieved, the real-time performance of stimulated Brillouin spectral analysis is improved, but also the accuracy and reliability of spectral analysis can be guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 A schematic structural diagram of a stimulated Brillouin spectroscopy analysis device provided by one embodiment of the present invention;

[0024] Figure 2 A schematic diagram of stimulated Brillouin spectroscopy analysis provided by one embodiment of the present invention;

[0025] Figure 3 A schematic diagram of the structure of a double-sideband IQ modulator provided by an embodiment of the present invention;

[0026] Figure 4 A schematic flow chart of a stimulated Brillouin spectroscopy analysis method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] It should be understood that the term "including" and other similar expressions in the specification or claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions, such as a process, method, system, or device including a series of steps or units is not limited to the listed steps or units. In addition, "first" and "second" are used to distinguish different objects, not to describe a specific order.

[0029] See also Figure 1 , a schematic structural diagram of a stimulated Brillouin spectroscopy analysis device provided by an embodiment of the present invention, the device comprising:

[0030] An optical circulator 110 is used to inject the light to be measured into the stimulated Brillouin medium;

[0031] The light to be measured is the light to be measured for pump detection, the light frequency is unknown, and it carries physical information, such as an optical signal of vibration, temperature, stress, etc. It can be the sensing light in the sensing system, or it can be a laser signal of unknown frequency with an extremely narrow line width. The light to be measured can be injected into the stimulated Brillouin medium through the optical circulator 110.

[0032] The optical circulator 110 has a first end for receiving the light to be measured, a second end connected to the stimulated Brillouin medium 120 , and a third end connected to the dense wavelength division multiplexer 160 .

[0033] The optical circulator 110 is also used to isolate the probe light. The optical circulator 110 can separate the backward Stokes light, the anti-Stokes light, the local oscillator light and the light to be measured, so as to prevent the probe light from affecting the light to be measured.

[0034] The stimulated Brillouin medium 120 is used to provide an optical medium for generating a stimulated Brillouin effect and generate characteristic frequency signals distributed on both sides of the probe light frequency in the frequency domain;

[0035] The stimulated Brillouin effect refers to the fact that when high-power pump light propagates in an optical fiber, the electrostrictive effect of the silicon material causes the refractive index to increase, thereby generating stimulated Brillouin scattering.

[0036] The light to be measured injected through the optical circulator and the double-sideband modulated probe light injected in reverse can generate Stokes light and anti-Stokes light in the stimulated Brillouin medium 120 .

[0037] The stimulated Brillouin medium can be a single-mode optical fiber, a multi-mode optical fiber, a photonic crystal optical fiber, or the like.

[0038] One end of the stimulated Brillouin medium 120 is connected to the optical circulator 110, and the other end is connected to the optical isolator 150, for receiving the probe light. The probe light refers to the single-frequency laser generated by the probe light source after double-sideband modulation.

[0039] The probe light source 130 is used to provide a single-frequency laser to stimulate the stimulated Brillouin effect;

[0040] Among them, the spectral linewidth of the light source is much smaller than the stimulated Brillouin gain width.

[0041] A double-sideband IQ modulator 140, used to generate frequency sidebands located on both sides of the probe light frequency by phase modulation, and perform frequency modulation according to the stimulated Brillouin frequency shift;

[0042] The double-sideband IQ modulator 140 can perform phase and frequency modulation on the single-frequency laser light generated by the probe light source 130. The probe light refers to a modulated optical signal originating from the probe light source.

[0043] The performing frequency modulation according to the stimulated Brillouin frequency shift comprises:

[0044] For the part with a frequency greater than the probe light frequency, anti-Stokes probe light and anti-Stokes local oscillator light are provided; for the part with a frequency less than the probe light frequency, Stokes probe light and Stokes local oscillator light are provided.

[0045] An optical isolator 150, used to maintain the direction of the single-frequency laser generated by the probe light source and to isolate other light generated by the stimulated Brillouin effect;

[0046] As a passive optical device that only allows unidirectional light to pass through, the optical isolator 150 can also maintain the directionality of other light generated by the stimulated Brillouin effect and prevent backward nonlinear optical signals and optical signals to be measured from entering the probe light source.

[0047] A dense wavelength division multiplexer 160 is used to separate the anti-Stokes light and the Stokes light located on both sides of the light to be measured and the probe light in the spectral line position;

[0048] The passband frequency interval of the wavelength division multiplexer 160 is between 10 GHz and 20 GHz.

[0049] An up-down frequency conversion detector 170, for detecting anti-Stokes light, Stokes light and corresponding local oscillator light signals respectively;

[0050] The up-down conversion detector 170 includes an up-conversion detector and a down-conversion detector.

[0051] The data acquisition board 180 is used to perform IQ demodulation according to the received optical signal, calculate the stimulated Brillouin complex gain, and obtain the optical information to be measured through inversion.

[0052] In this embodiment, the double-sideband IQ modulator modulates the single-frequency laser generated by the probe light source to generate frequencies of and The probe light and the two local oscillator lights generated by cross mixing and The modulated probe light and local oscillator light are injected into the stimulated Brillouin medium through the optical isolator. The optical isolator ensures that the light to be measured and other signals generated in the stimulated Brillouin medium do not affect the operation of the probe light source. In the stimulated Brillouin medium, the modulated probe light will generate a new frequency under the influence of the stimulated Brillouin effect, and the frequency shift is Due to the influence of Stokes and anti-Stokes effects, the two probe lights and the local oscillator light frequencies are on both sides of the probe light. After interacting with the light to be measured, the intensity and phase information of the light to be measured can be obtained simultaneously by demodulating the changes of different signals.

[0053] The up-conversion and down-conversion signals of the probe light affected by the Brillouin effect are separated according to frequency by a dense wavelength division multiplexer. The separated signals are used by up-conversion detectors and down-conversion detectors to obtain the interaction information between the local oscillator signal and the signal to be measured according to the frequency, and are input into the data acquisition board for IQ demodulation and data processing, and the spectral information of the light to be measured is obtained by inversion.

[0054] In this embodiment, it is proposed to compress the spectral information into the radio frequency range, convert the optical frequency signal into the radio frequency signal by heterodyne measurement, no longer rely on the narrow bandwidth characteristics of SBS as an optical filter, and use the characteristics of SBS frequency shift wavelength sensitivity to achieve broadband signal compression, receive spectral information in the radio frequency range, thereby achieving high-resolution spectral analysis without scanning, and improving the real-time performance of spectral analysis. At the same time, the changes in Brillouin gain and phase are measured by IQ demodulation to reduce the influence of optical power fluctuations on the measurement, and the information of Stokes and anti-Stokes interactions is combined to eliminate the dependence on Brillouin frequency offset in the optical fiber, so that the measurement method is not affected by temperature fluctuations, and the analysis results are accurate and reliable.

[0055] In some embodiments, Figure 2 As shown, 201 represents probe light, 202 represents anti-Stokes probe light, 203 represents Stokes probe light, 204 represents anti-Stokes local oscillator light, 205 represents Stokes local oscillator light, 206 represents light to be measured, 207 represents Stokes gain, 208 represents anti-Stokes gain, 209 represents stimulated Brillouin frequency shift, and 210 represents frequency offset of light to be measured.

[0056] The frequency of the probe light 201 is Under the action of the double-sideband IQ modulator, an anti-Stokes probe light 202 and a Stokes light probe light 203 will be generated, and the modulation frequencies are and , the frequencies of the generated anti-Stokes probe light 202 and Stokes light probe light 203 are: and Correspondingly, in the case of double-sideband modulation, a group of local oscillator lights will also be generated, namely, anti-Stokes local oscillator light 204 and Stokes local oscillator light 205, and the frequencies of the two local oscillator lights are respectively and .

[0057] It should be noted that during the IQ modulation process, the two modulation frequencies should be set to have a large difference, such as , , to avoid the interaction between the local oscillator light and the Stokes gain 207 and the anti-Stokes gain 208 ( and ) have overlapping parts, resulting in the two local oscillator lights 204 and 205 participating in the stimulated Brillouin frequency shift 209 ( ), thus affecting demodulation. The detected light 206 (frequency is ) The optical signal interacting with the probe light 201 carries the information of the light to be measured in amplitude and phase due to the influence of Stokes gain 207 and anti-Stokes gain 208, and the overall frequency change is related to the stimulated Brillouin gain.

[0058] The complex gain of stimulated Brillouin gain in the Stokes and anti-Stokes directions can be expressed as follows:

[0059] ;

[0060] ;

[0061] Due to the presence of the light to be measured 206, the Stokes and anti-Stokes signals generated by the probe light 201 exist in the frequency shift related to the light to be measured, and are expressed as different frequency quantities in different directions, that is,

[0062] ;

[0063] ;

[0064] When the frequency of the probe light 201 is known, the frequency offset between the measured light 206 and the initial frequency of the probe light 201 can be inferred from the frequencies of the two probe lights:

[0065] ;

[0066] The two local oscillator lights 204 and 205 that are not involved in the generation process of Stokes light and anti-Stokes light can be combined with the frequency changes of Stokes probe light 202 and anti-Stokes probe light 203 to demodulate the complex gain of Stokes light and anti-Stokes light. In the above calculation process, the complex gain is the measurement data, and all frequencies except the frequency of the light to be measured 206 are known frequencies. Therefore, the unknown spectral changes can be accurately calculated by this method of detecting the nonlinear frequency shift measurement. Benefiting from the Brillouin linewidth of only 30MHz, the overall spectral resolution can be close to the stimulated Brillouin linewidth.

[0067] In one embodiment, Figure 3 As shown, the double-sideband IQ modulator includes a high frequency phase modulator 310 , an intermediate frequency phase modulator 320 , a digital frequency synthesizer 330 , a digital phase shifter 340 and a frequency divider 350 .

[0068] The high-frequency phase modulator 310 is connected to the probe light source and is used to generate a modulation signal with a frequency greater than the stimulated Brillouin shift frequency, and the probe light output after modulation by the high-frequency phase modulator is modulated by the intermediate frequency phase modulator;

[0069] The operating frequency of the intermediate frequency phase modulator 320 is much smaller than the stimulated Brillouin frequency shift, and is used to generate local oscillator light that does not participate in the stimulated Brillouin process;

[0070] In order to prevent the phase difference between the modulation signals from affecting the demodulation, the modulation signals are generated by the same digital frequency synthesizer 330. The digital frequency synthesizer 330 is used to generate a unified modulation signal, and the output frequency is the working frequency of the high-frequency phase modulator. The output signal is divided into two paths, one of which passes through the digital phase shifter 340 to adjust the phase of the output drive signal, which is used to control the phase difference of the IQ signal, and the other passes through the frequency divider 350 to reduce the frequency to the intermediate frequency phase modulator 320 to drive the intermediate frequency phase modulator.

[0071] Preferably, the digital frequency synthesizer 330 is used to output the radio frequency signal required by the high frequency modulator and the intermediate frequency phase modulator, and the signal is a sinusoidal wave signal greater than 10 GHz;

[0072] Wherein, the timing of the digital frequency synthesizer is controlled by a data acquisition board;

[0073] The digital phase shifter is used to adjust the phase of the input electrical signal, and the adjustment range is between -π / 2 and π / 2;

[0074] The frequency divider is used to perform a division operation on the input electrical signal and output the result.

[0075] The operating frequency of the high frequency phase modulator 310 is a positive multiple of the operating frequency of the intermediate frequency phase modulator 320, so as to avoid system errors caused by phase jitter and frequency shift.

[0076] Figure 4 A schematic diagram of a stimulated Brillouin spectroscopy analysis method provided by an embodiment of the present invention, the method comprising:

[0077] S401, injecting the light to be measured into the stimulated Brillouin medium through an optical circulator;

[0078] Wherein, the optical circulator is also used to isolate the probe light.

[0079] S402, modulating the single-frequency laser generated by the probe light source in a double-sideband IQ modulator, generating frequency sidebands located on both sides of the probe light frequency through phase modulation, performing frequency modulation according to the stimulated Brillouin frequency shift, and injecting the modulated single-frequency laser into the stimulated Brillouin medium through an optical isolator;

[0080] Specifically, performing frequency modulation according to the stimulated Brillouin frequency shift includes:

[0081] For the part with a frequency greater than the probe light frequency, anti-Stokes probe light and anti-Stokes local oscillator light are provided;

[0082] For the part whose frequency is smaller than the probe light, Stokes light probe light and Stokes local oscillator light are provided.

[0083] The isolator shown can be used to maintain the direction of the single-frequency laser generated by the probe light source and isolate other light generated by the stimulated Brillouin effect.

[0084] S403, based on the stimulated Brillouin effect, generating characteristic frequency signals distributed on both sides of the probe light frequency in the frequency domain;

[0085] In a stimulated Brillouin medium, characteristic frequency signals distributed on both sides of the probe light frequency can be generated based on the stimulated Brillouin effect.

[0086] S404, receiving and separating the anti-Stokes light and the Stokes light located on both sides of the light to be measured and the probe light at the spectral line position by a dense wavelength division multiplexer, and detecting the anti-Stokes light, the Stokes light and the corresponding local oscillator light signal by an up-down frequency conversion detector;

[0087] The dense wavelength division multiplexer is connected to the optical circulator, and after receiving the optical signal generated in the stimulated Brillouin medium, it can be used to separate the anti-Stokes light and the Stokes light located on both sides of the light to be measured and the probe light in the spectral line position.

[0088] S405 , performing IQ demodulation according to the collected optical signal, calculating the stimulated Brillouin complex gain, and obtaining the optical information to be measured through inversion.

[0089] The received optical signal can be demodulated by the data acquisition board and the optical information to be measured can be obtained by inversion.

[0090] In one embodiment, the double-sideband IQ modulator includes a high frequency phase modulator, an intermediate frequency phase modulator, a digital frequency synthesizer, a digital phase shifter and a frequency divider;

[0091] The high-frequency phase modulator is used to generate a modulation signal with a frequency greater than the stimulated Brillouin shift frequency, and the probe light output after modulation by the high-frequency phase modulator is modulated by the intermediate frequency phase modulator;

[0092] The intermediate frequency phase modulator is used to generate local oscillation light that does not participate in the stimulated Brillouin process;

[0093] The digital frequency synthesizer is used to generate a unified modulation signal, and the output frequency is the operating frequency of the high-frequency phase modulator. The output signal is divided into two paths, one path passes through the digital phase shifter to adjust the phase of the output drive signal, which is used to control the phase difference of the IQ signal, and the other path passes through the frequency divider to reduce the frequency to the intermediate frequency phase modulator to drive the intermediate frequency phase modulator.

[0094] Preferably, the modulation frequency of the high frequency phase modulator is greater than 10 GHz, and the modulation frequency of the intermediate frequency phase modulator is between 80 MHz and 160 MHz;

[0095] The digital frequency synthesizer is used to output the radio frequency signal required by the high frequency modulator and the intermediate frequency phase modulator, and the signal is a sine wave signal greater than 10 GHz;

[0096] Wherein, the timing of the digital frequency synthesizer is controlled by a data acquisition board;

[0097] The digital phase shifter is used to adjust the phase of the input electrical signal, and the adjustment range is between -π / 2 and π / 2;

[0098] The frequency divider is used to perform a division operation on the input electrical signal and output the result.

[0099] Wherein, the operating frequency of the high frequency phase modulator is a positive multiple of the operating frequency of the intermediate frequency phase modulator.

[0100] It should be understood that the serial numbers of the steps in the above embodiments do not imply a sequence of execution, and the execution sequence of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0101] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and modules described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0102] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0103] As described above, 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 the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. 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 embodiments of the present invention.

Claims

1. A stimulated Brillouin spectroscopy analysis device, characterized in that: include: An optical circulator, used for injecting the light to be measured into the stimulated Brillouin medium; Stimulated Brillouin medium, used to provide an optical medium for generating stimulated Brillouin effect, and to generate characteristic frequency signals distributed on both sides of the probe light frequency in the frequency domain; A probe light source, used to provide a single-frequency laser to stimulate the stimulated Brillouin effect; A double-sideband IQ modulator, used to generate frequency sidebands located on both sides of the probe light frequency through phase modulation, and perform frequency modulation according to the stimulated Brillouin frequency shift; An optical isolator, used to maintain the direction of the single-frequency laser generated by the probe light source and isolate other light generated by the stimulated Brillouin effect; A dense wavelength division multiplexer is used to separate the anti-Stokes light and the Stokes light located on both sides of the light to be measured and the probe light in the spectral line position; Up and down conversion detectors, used to detect anti-Stokes light, Stokes light and corresponding local oscillator light signals respectively; The data acquisition board is used to perform IQ demodulation according to the received optical signal, calculate the stimulated Brillouin complex gain, and obtain the optical information to be measured through inversion.

2. The device according to claim 1, characterized in that The optical circulator is also used to isolate the probe light.

3. The device according to claim 1, characterized in that The double-sideband IQ modulator includes a high-frequency phase modulator, an intermediate-frequency phase modulator, a digital frequency synthesizer, a digital phase shifter and a frequency divider; The high-frequency phase modulator is used to generate a modulation signal with a frequency greater than the stimulated Brillouin shift frequency, and the probe light output after modulation by the high-frequency phase modulator is modulated by the intermediate frequency phase modulator; The intermediate frequency phase modulator is used to generate local oscillation light that does not participate in the stimulated Brillouin process; The digital frequency synthesizer is used to generate a unified modulation signal, and the output frequency is the operating frequency of the high-frequency phase modulator. The output signal is divided into two paths, one path passes through the digital phase shifter to adjust the phase of the output drive signal, which is used to control the phase difference of the IQ signal, and the other path passes through the frequency divider to reduce the frequency to the intermediate frequency phase modulator to drive the intermediate frequency phase modulator.

4. The device according to claim 3, characterized in that The modulation frequency of the high frequency phase modulator is greater than 10 GHz, and the modulation frequency of the intermediate frequency phase modulator is between 80 MHz and 160 MHz; The digital frequency synthesizer is used to output the radio frequency signal required by the high frequency modulator and the intermediate frequency phase modulator, and the signal is a sine wave signal greater than 10 GHz; Wherein, the timing of the digital frequency synthesizer is controlled by a data acquisition board; The digital phase shifter is used to adjust the phase of the input electrical signal, and the adjustment range is between -π / 2 and π / 2; The frequency divider is used to perform a division operation on the input electrical signal and output the result.

5. The device according to claim 3, characterized in that The operating frequency of the high frequency phase modulator is a positive multiple of the operating frequency of the intermediate frequency phase modulator.

6. The device according to claim 1, characterized in that The frequency modulation according to the stimulated Brillouin frequency shift comprises: For the part with a frequency greater than the probe light frequency, anti-Stokes probe light and anti-Stokes local oscillator light are provided; For the part whose frequency is smaller than the probe light, Stokes light probe light and Stokes local oscillator light are provided.

7. A stimulated Brillouin spectroscopy analysis method, characterized in that: include: The light to be measured is injected into the stimulated Brillouin medium through an optical circulator; The single-frequency laser generated by the probe light source is modulated in a double-sideband IQ modulator, and frequency sidebands located on both sides of the probe light frequency are generated by phase modulation. The frequency is modulated according to the stimulated Brillouin frequency shift, and the modulated single-frequency laser is injected into the stimulated Brillouin medium through an optical isolator. Based on the stimulated Brillouin effect, characteristic frequency signals distributed on both sides of the probe light frequency are generated in the frequency domain; The anti-Stokes light and the Stokes light located on both sides of the light to be measured and the probe light at the spectral line position are received and separated by a dense wavelength division multiplexer, and the anti-Stokes light, the Stokes light and the corresponding local oscillator light signals are detected by an up-down frequency conversion detector; IQ demodulation is performed according to the collected optical signal, the stimulated Brillouin complex gain is calculated, and the light information to be measured is obtained through inversion.

8. The method according to claim 7, characterized in that The double-sideband IQ modulator includes a high-frequency phase modulator, an intermediate-frequency phase modulator, a digital frequency synthesizer, a digital phase shifter and a frequency divider; The high-frequency phase modulator is used to generate a modulation signal with a frequency greater than the stimulated Brillouin shift frequency, and the probe light output after modulation by the high-frequency phase modulator is modulated by the intermediate frequency phase modulator; The intermediate frequency phase modulator is used to generate local oscillation light that does not participate in the stimulated Brillouin process; The digital frequency synthesizer is used to generate a unified modulation signal, and the output frequency is the operating frequency of the high-frequency phase modulator. The output signal is divided into two paths, one path passes through the digital phase shifter to adjust the phase of the output drive signal, which is used to control the phase difference of the IQ signal, and the other path passes through the frequency divider to reduce the frequency to the intermediate frequency phase modulator to drive the intermediate frequency phase modulator.

9. The method according to claim 8, characterized in that The operating frequency of the high frequency phase modulator is a positive multiple of the operating frequency of the intermediate frequency phase modulator.

10. The method according to claim 7, characterized in that The frequency modulation according to the stimulated Brillouin frequency shift comprises: For the part with a frequency greater than the probe light frequency, anti-Stokes probe light and anti-Stokes local oscillator light are provided; For the part whose frequency is smaller than the probe light, Stokes light probe light and Stokes local oscillator light are provided.

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