Rapid BOTDA sensing device and method based on noise chirp modulation

Abstract

The invention relates to the technical field of distributed optical fiber sensing, and discloses a rapid BOTDA (Brillouin Optical Time Domain Analysis) sensing device and method based on noise chirp modulation. Wherein a first light beam is modulated by an electro-optical modulator to realize frequency shift and spectrum broadening to form wide-spectrum light, the wide-spectrum light passes through a first semiconductor optical amplifier and a first circulator and then enters a chirp fiber bragg grating, and pulse light with frequency continuously distributed in time is output and then enters one end of a sensing optical fiber as detection light; the second light beam passes through a second semiconductor optical amplifier, a scrambler and a second optical circulator and then enters from the other end of the sensing optical fiber as pump light; the probe light and the pump light are subjected to stimulated Brillouin scattering in the sensing optical fiber, and the probe light carrying Brillouin scattering information is detected by the detection module and then sent to the data acquisition and analysis system to demodulate sensing information. According to the invention, the measurement speed can be obviously improved, and a basis is provided for dynamic strain measurement.

Description

Technical Field

[0001] This invention relates to the field of distributed optical fiber sensing technology, specifically a fast BOTDA (Brillouin Optical Time Domain Analysis) sensing device and method based on noise chirp modulation. Background Technology

[0002] Brillouin optical time-domain analysis (BOTDA) is a fiber optic sensing technology based on the Brillouin scattering principle. It boasts advantages such as long sensing distance and high measurement accuracy, enabling precise measurements of physical quantities like temperature and strain. Therefore, it is widely used in numerous fields, including power equipment, oil and gas pipelines, and bridges and tunnels. The measurement speed of a BOTDA system is primarily limited by the length of the sensing fiber, the number of signal acquisition averaging attempts, the number of probe light frequency scan points, and the frequency switching time. To improve the system's measurement speed, one approach is to reduce the number of averaging attempts, such as using polarization-independent schemes. Another approach is to increase the frequency switching rate during Brillouin spectrum acquisition or eliminate the frequency scanning process, using methods such as optical frequency agility schemes, optical frequency comb schemes, Brillouin spectrum ramp-assisted schemes, and optical chirped chain schemes.

[0003] Optical frequency agility schemes achieve rapid measurement by quickly switching the probe light frequency, but still require frequency sweeping, and the arbitrary waveform generators used are expensive, resulting in high system costs. Optical frequency comb schemes utilize parallel detection of frequency comb components, but spatial resolution is limited by the frequency comb spacing and the Fast Fourier Transform (FFT) time window, and system costs are high. Brillouin spectroscopy ramp-assisted schemes simplify measurement using the linear region of the BGS ramp, but have a small dynamic range and are significantly affected by pump power fluctuations and polarization changes. Optical chirped chain schemes achieve rapid measurement by cascading chirped pulse segments, but the amplitude response of different frequency components is uneven, affecting measurement accuracy, and a high-bandwidth arbitrary waveform generator is required to generate the chirped pulses, increasing system costs.

[0004] In conclusion, existing BOTDA measurement devices need to be improved to address issues such as limited measurement speed and high system cost. Summary of the Invention

[0005] To improve the measurement speed of BOTDA systems while reducing the complexity and cost of the devices, this invention proposes a fast BOTDA sensing device and method based on noise chirp modulation.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a fast BOTDA sensing device based on noise chirp modulation, comprising a narrow linewidth laser; the laser output from the narrow linewidth laser is split into a first beam and a second beam after passing through a polarization-maintaining coupler, wherein the first beam is incident on an electro-optic modulator driven by noise and radio frequency signal mixing, and the electro-optic modulator modulates to achieve frequency shifting and spectral broadening, and the resulting wide-spectrum light is modulated into pulse light by a first semiconductor optical amplifier, the pulse light is incident on a chirped Bragg fiber grating after passing through a first circulator, the chirped Bragg fiber grating is used to reflect the pulse light to disperse it into pulse light with a continuous frequency distribution in time; the pulse light reflected by the chirped Bragg fiber grating is output by the first circulator and is incident on one end of the sensing fiber as probe light; the second beam is modulated into pulse light by a second semiconductor optical amplifier, and then passes through a polarization scrambler and a second circulator in sequence and is incident on the other end of the sensing fiber as pump light; The probe light and pump light propagate in opposite directions in the sensing fiber and undergo stimulated Brillouin scattering. The probe light carrying Brillouin scattering information is output by the second circulator, detected by the detection module, and then sent to the data acquisition and analysis system for acquisition, analysis, and processing. Finally, the temperature or strain distribution and its magnitude along the sensing fiber are demodulated.

[0007] The detection module includes a filter and a photodetector. The filter is used to filter out Stokes light or anti-Stokes light from the detection light before sending it to the photodetector. The photodetector is used to perform photoelectric conversion.

[0008] The fast BOTDA sensing device based on noise chirp modulation further includes a microwave signal source, a noise source, and a mixer. The output terminals of the microwave signal source and the noise source are respectively connected to the input terminal of the mixer. The output terminal of the mixer is connected to the radio frequency drive terminal of the electro-optic modulator. The noise source is used to output a Gaussian white noise signal, and the microwave signal source is used to output a microwave signal with a frequency equal to the Brillouin frequency shift.

[0009] The Gaussian white noise signal output by the noise source has a bandwidth greater than 300MHz and an amplitude greater than 20dBm.

[0010] The electro-optic modulator is used to perform carrier suppression modulation on the first beam to obtain two sidebands with a frequency shift equal to the Brillouin frequency shift, and to achieve spectral broadening of the first beam.

[0011] The electro-optic modulator is used to modulate the first beam to achieve a frequency shift equal to the Brillouin frequency shift, and to achieve a spectral broadening with a spectral width range of 200-300MHz.

[0012] The fast BOTDA sensing device based on noise chirp modulation further includes a pulse generator. The output terminal of the pulse generator is connected to the electrical drive terminals of the first semiconductor optical amplifier and the second semiconductor optical amplifier, respectively, for synchronously driving the first semiconductor optical amplifier and the second semiconductor optical amplifier to perform pulse modulation.

[0013] The first port of the first circulator is connected to the output of the first semiconductor optical amplifier, the second port is connected to the input of the chirped Bragg fiber grating, and the third port is connected to one end of the sensing fiber; the first port of the second optical circulator is connected to the output of the polarization scrambler, the second port is connected to the other end of the sensing fiber, and the third port is connected to the input of the filter.

[0014] The narrow linewidth laser is a laser with a linewidth of less than 10 kHz, and the dispersion coefficient of the chirped Bragg fiber grating is greater than -5000 ps / nm.

[0015] Furthermore, a fast BOTDA sensing method based on noise chirp modulation, implemented using the aforementioned sensing device, includes the following steps: S1. Start the device to cause stimulated Brillouin scattering of the probe light and pump light in the sensing fiber. S2. Acquire Stokes light or anti-Stokes light signals carrying Brillouin scattering through a data acquisition and analysis system; S3. Process the acquired signal, reconstruct the Brillouin gain spectrum by analyzing the time-domain waveform, and demodulate the temperature or strain distribution information along the sensing fiber based on the Brillouin gain spectrum.

[0016] Compared with the prior art, the present invention has the following advantages: 1. Significantly Improved Measurement Speed: Traditional BOTDA technology requires frequency scanning to measure the complete Brillouin gain spectrum, a time-consuming process. This invention utilizes noise modulation combined with chirped fiber grating dispersion to generate a continuous frequency scanning light (chirped chain) covering the entire Brillouin gain spectrum bandwidth in a single operation. By analyzing the time-series signal of a single or a small number of scattered light bursts, the Brillouin gain spectrum can be reconstructed, fundamentally avoiding point-by-point frequency scanning and greatly improving measurement speed.

[0017] 2. Improved measurement accuracy and signal-to-noise ratio: Compared with the simple optical chirped chain scheme, the present invention introduces noise modulation to actively broaden the probe light spectrum, so that the optical power fluctuation of the final "chirped chain" at different frequency components tends to be uniform, effectively avoiding the additional noise introduced by uneven amplitude response, which helps to improve the signal-to-noise ratio and measurement accuracy.

[0018] 3. Reduced system cost and complexity: This invention uses mature devices such as noise sources, conventional microwave sources, semiconductor optical amplifiers, and chirped gratings, avoiding the use of high-cost and high-complexity arbitrary waveform generators or femtosecond optical frequency combs. While achieving rapid measurement, it effectively controls system cost and complexity.

[0019] In summary, this invention proposes a fast BOTDA sensing and measurement device and method based on noise chirp modulation. By combining noise modulation and chirp dispersion techniques in the probe optical path, it achieves fast distributed measurement while maintaining measurement accuracy, and reduces system complexity and cost. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the fast BOTDA sensing device based on noise chirp modulation provided in Embodiment 1 of the present invention. Figure 2 This is a schematic diagram of the modulation principle of the second beam in an embodiment of the present invention; Figure 3 This is a schematic diagram of the modulation principle of the first beam in an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the principle of stimulated Brillouin interaction between two light sources within the sensing fiber in this invention.

[0021] In the diagram: 1. Narrow linewidth laser; 2. Polarization-maintaining coupler; 3. Electro-optic modulator; 4. Mixer; 5. Microwave signal source; 6. Noise source; 7. First semiconductor optical amplifier; 8. Pulse generator; 9. First circulator; 10. Chirped Bragg fiber grating; 11. Second semiconductor optical amplifier; 12. Polarization scrambler; 13. Second circulator; 14. Sensing fiber; 15. Filter; 16. Photodetector; 17. Data acquisition and analysis system. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1 like Figure 1As shown, Embodiment 1 of the present invention provides a fast BOTDA sensing device based on noise chirp modulation, including a narrow linewidth laser 1, a polarization-maintaining coupler 2, an electro-optic modulator 3, a first semiconductor optical amplifier 7, a first circulator 9, a chirped Bragg fiber grating 10, a second semiconductor optical amplifier 11, a polarization scrambler 12, a second circulator 13, a sensing fiber 14, a detection module, and a data acquisition and analysis system 17.

[0024] The laser output from the narrow linewidth laser 1 is split into a first beam and a second beam after passing through the polarization-maintaining coupler 2. The first beam is incident on the noise and radio frequency driven electro-optic modulator 3, which modulates the light to achieve frequency shifting and spectral broadening, resulting in a wide-spectrum light. After being modulated by the electro-optic modulator 3, it is modulated into pulsed light by the first semiconductor optical amplifier 7. The pulsed light passes through the first circulator 9 and is then incident on the chirped Bragg fiber grating 10. The chirped Bragg fiber grating 10 is used to reflect the pulsed light, causing it to disperse into pulsed light with a continuous frequency distribution in time. The pulsed light reflected by the chirped Bragg fiber grating 10 is output by the first circulator 9 and is incident as probe light on one end of the sensing fiber 14. The second beam is modulated into pulsed light by the second semiconductor optical amplifier 11, and then passes through the polarization scrambler 12 and the second circulator 13 in sequence before being incident as pump light from the other end of the sensing fiber 14.

[0025] In this embodiment, the probe light and pump light propagate in opposite directions in the sensing fiber 14 and undergo stimulated Brillouin scattering. The probe light carrying Brillouin scattering information is output by the second circulator 13, detected by the detection module, and sent to the data acquisition and analysis system 17 for acquisition, analysis and processing. Finally, the temperature or strain distribution and its magnitude along the sensing fiber are demodulated.

[0026] In this embodiment, the first circulator 9 and the second circulator 13 can be fiber optic circulators, and the optical path transmission and connection between the various optical devices are achieved through fiber optic patch cords.

[0027] Specifically, in this embodiment, the detection module includes a filter 15 and a photodetector 16. The filter 15 is used to filter out Stokes light or anti-Stokes light in the detection light and then send it to the photodetector 16. The photodetector 16 is used to perform photoelectric conversion.

[0028] Furthermore, this embodiment of a fast BOTDA sensing device based on noise chirp modulation further includes a microwave signal source 5, a noise source 6, and a mixer 4. The outputs of the microwave signal source 5 and the noise source 6 are respectively connected to the input of the mixer 4, and the output of the mixer 4 is connected to the radio frequency drive of the electro-optic modulator 3. The noise source 6 is used to output a Gaussian white noise signal, and the microwave signal source 5 is used to output a microwave signal with a frequency equal to the Brillouin frequency shift. The mixer 4 is used to mix the sinusoidal signal generated by the microwave signal source 5 with the noise signal generated by the noise source 6.

[0029] Furthermore, in this embodiment, the Gaussian white noise signal output by the noise source 6 has a bandwidth greater than 300MHz and an amplitude greater than 20dBm.

[0030] Specifically, such as Figure 2 As shown, in this embodiment, the second beam with frequency v0 is pulse-modulated by the second semiconductor optical amplifier 11 into a periodic pulse beam with frequency v0.

[0031] Specifically, such as Figure 3 As shown, in this embodiment, the electro-optic modulator 3 is used to perform carrier suppression modulation on the first beam to obtain a frequency shift f. RF This is equal to the two sidebands of the Brillouin frequency shift, and the spectral broadening used to achieve the first beam. Here, v0 represents the frequency of the first beam entering the electro-optic modulator 3. After passing through the electro-optic modulator 3, the output laser, in addition to the carrier wave with frequency v0, also includes beams with frequencies v0-f... RF and v0+f RF Furthermore, under the influence of noise signals, the frequencies of the two sidebands are broadened. The frequencies are v0-f. RF and v0+f RF The two widebands of the light spectrum are modulated into periodic pulses by the first semiconductor optical amplifier 7. Then, the chirped Bragg fiber grating 10 disperses the pulse-modulated wideband pulse light signal, broadening it in the time domain and forming a chirped chain of light signals with a linear and continuous frequency distribution in time. The dispersed light signal can just cover the time-domain occupied area of ​​the original pulse sequence, forming a continuous frequency scanning effect with the beginning and end connected.

[0032] Specifically, in this embodiment, the electro-optic modulator 3 is used to modulate the first beam to achieve a frequency shift f. RF Equal to Brillouin frequency shift f BFS The frequency shifting and spectral broadening are achieved to a spectral width range of 200-300MHz. The frequency shifting is to enable Brillouin scattering between the probe light and the pump light of the subsequent pulse in the sensing fiber, while the spectral broadening is to work with the chirped Bragg fiber grating 10 to achieve the output of pulsed light with a continuous frequency distribution in time.

[0033] Furthermore, such as Figure 1 As shown, the fast BOTDA sensing device based on noise chirp modulation further includes a pulse generator 8. The output terminal of the pulse generator 8 is connected to the electrical drive terminals of the first semiconductor optical amplifier 7 and the second semiconductor optical amplifier 11, respectively, for synchronously driving the first semiconductor optical amplifier 7 and the second semiconductor optical amplifier 11 to perform pulse modulation.

[0034] Specifically, in this embodiment, the first port of the first circulator 9 is connected to the output of the first semiconductor optical amplifier 7, the second port is connected to the input of the chirped Bragg fiber grating 10, and the third port is connected to one end of the sensing fiber 14; the first port of the second circulator 13 is connected to the output of the polarizer 12, the second port is connected to the other end of the sensing fiber 14, and the third port is connected to the input of the filter 15.

[0035] Specifically, in this embodiment, the narrow linewidth laser 1 is a laser with a linewidth of less than 10kHz, and the dispersion coefficient of the chirped Bragg fiber grating 10 is greater than -5000ps / nm.

[0036] Specifically, in this embodiment, the connection relationships of each device are as follows: the output terminal of the narrow linewidth laser 1 is connected to the input terminal of the polarization-maintaining coupler 2; the first output terminal of the polarization-maintaining coupler 2 is connected to the input terminal of the electro-optic modulator 3; the output terminals of the microwave signal source 5 and the noise source 6 are respectively connected to the two input terminals of the mixer 4; the signal output terminal of the mixer 4 is connected to the RF drive terminal of the electro-optic modulator 3; the optical output terminal of the electro-optic modulator 3 is connected to the input terminal of the first semiconductor optical amplifier 7; one output terminal of the pulse generator 8 is connected to the electrical drive terminal of the first semiconductor optical amplifier 7; the output terminal of the first semiconductor optical amplifier 7 is connected to the first port of the first circulator 9; the second port of the first circulator 9 is connected to the input terminal of the chirped Bragg fiber grating 10; and the third port of the first circulator 9 is connected to one end of the sensing fiber 14.

[0037] The second output terminal of polarization-maintaining coupler 2 is connected to the optical input terminal of the second semiconductor optical amplifier 11; the other output terminal of pulse generator 8 is connected to the electrical drive terminal of the second semiconductor optical amplifier 11; the optical output terminal of the second semiconductor optical amplifier 11 is connected to the input terminal of polarization scrambler 12; the output terminal of polarization scrambler 12 is connected to the first port of second circulator 13; the second port of second circulator 13 is connected to the other end of sensing optical fiber 14; the third terminal of second circulator 13 is connected to the input terminal of filter 15; the output terminal of filter 15 is connected to the optical input terminal of photodetector 16; and the electrical output terminal of photodetector 16 is connected to the input terminal of data acquisition and analysis system 17.

[0038] The working principle of a fast BOTDA sensing device based on noise chirp modulation in this embodiment is as follows: The laser output from the narrow linewidth laser 1 is incident on the polarization-maintaining coupler 2 and split into two beams: one beam enters the probe optical path and the other beam enters the pump optical path.

[0039] The laser beam entering the detection optical path enters the electro-optic modulator 3. The electro-optic modulator 3 is driven by the superposition of a sinusoidal signal from the mixer 4 and a noise signal, thereby frequency-shifting and modulating the narrow-linewidth laser into broadband light. This broadband light, after passing through the first semiconductor optical amplifier 7 driven by the pulse generator 8, is modulated into periodic pulses. These pulses then enter the chirped Bragg fiber grating 10 via the first circulator 9, where they are dispersed and broadened into a chirped light signal with a continuously varying frequency in the time domain. This chirped light signal is then incident on one end of the sensing fiber 14 via the first circulator 9.

[0040] The laser beam entering the pump optical path is modulated into pulsed light by the second semiconductor optical amplifier 11 driven by the pulse generator 8. After the polarization state of the pulsed light is disturbed by the polarizer 12, it is incident on the other end of the sensing optical fiber 14 through the second circulator 13.

[0041] like Figure 4 As shown, in the sensing fiber 14, since the frequency difference between the two sidebands of the pulse probe light and the pulse pump light is equal to the Brillouin frequency shift f BFS The opposing pulsed pump light then undergoes stimulated Brillouin scattering with the chirped chain of pulsed probe light whose frequency changes continuously in the time domain. The probe light, carrying Brillouin scattering information, is output from the third port of the second circulator 13 and enters the filter 15. After the filter 15 filters out the Stokes light or anti-Stokes light components, the optical signal is converted into an electrical signal by the photodetector 16. This electrical signal is transmitted to the data acquisition and analysis system 17 via a cable, and after processing, the temperature or strain distribution information along the sensing fiber can be demodulated.

[0042] Example 2 Embodiment 2 of the present invention provides a fast BOTDA sensing method based on noise chirp modulation, based on Figure 1 The aforementioned sensing device is implemented by including the following steps: S1. Start the device to cause stimulated Brillouin scattering of the probe light and pump light in the sensing fiber 14. S2. Acquire Stokes light or anti-Stokes light signals carrying Brillouin scattering through the data acquisition and analysis system 17; S3. Process the acquired signal, reconstruct the Brillouin gain spectrum by analyzing the time-domain waveform, and demodulate the temperature or strain distribution information along the sensing fiber based on the Brillouin gain spectrum.

[0043] Specifically, in this embodiment, data is acquired, analyzed and processed by the data acquisition and analysis system 17, and the Brillouin gain spectrum is reconstructed by analyzing the time-domain waveform. Finally, the temperature or strain distribution information along the sensing fiber 14 is obtained by demodulation.

[0044] In summary, this invention provides a fast BOTDA sensing device and method based on noise chirp modulation. The probe light is noise-modulated to broaden its spectrum, and then dispersed by a chirped grating to form a time-domain frequency scanning light. This allows for the excitation of interactions across the entire bandwidth of the Brillouin gain spectrum under test in a single measurement. By analyzing the time-domain waveform of the scattered light, the Brillouin gain spectrum distributed along the optical fiber can be retrieved, thus avoiding the traditional point-by-point frequency scanning process, significantly improving the measurement speed, and providing an effective technical means for realizing dynamic strain measurement.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fast BOTDA sensing device based on noise chirp modulation, characterized in that, The system includes a narrow linewidth laser (1); the laser output from the narrow linewidth laser (1) is split into a first beam and a second beam after passing through a polarization-maintaining coupler (2). The first beam is incident on an electro-optic modulator (3) driven by noise and radio frequency signal mixing. After being modulated by the electro-optic modulator (3), frequency shifting and spectral broadening are achieved. The resulting wide-spectrum light is modulated into pulse light by a first semiconductor optical amplifier (7). The pulse light is incident on a chirped Bragg fiber grating (10) after passing through a first circulator (9). The chirped Bragg fiber grating (10) is used to reflect the pulse light and disperse it into pulse light with a frequency continuously distributed in time. The pulse light reflected by the chirped Bragg fiber grating (10) is output by the first circulator (9) and then used as probe light to be incident on one end of the sensing fiber (14). The second beam is modulated into pulse light by a second semiconductor optical amplifier (11), and then passes through a polarization scrambler (12) and a second circulator (13) in sequence before being used as pump light to be incident on the other end of the sensing fiber (14). The probe light and pump light propagate in opposite directions in the sensing fiber (14) and undergo stimulated Brillouin scattering. The probe light carrying Brillouin scattering information is output by the second circulator (13), detected by the detection module, and sent to the data acquisition and analysis system (17) for acquisition, analysis and processing. Finally, the temperature or strain distribution and its magnitude along the sensing fiber are demodulated.

2. The fast BOTDA sensing device based on noise chirp modulation according to claim 1, characterized in that, The detection module includes a filter (15) and a photodetector (16). The filter (15) is used to filter out Stokes light or anti-Stokes light in the detection light and then send it to the photodetector (16). The photodetector (16) is used to perform photoelectric conversion.

3. The fast BOTDA sensing device based on noise chirp modulation according to claim 1, characterized in that, It also includes a microwave signal source (5), a noise source (6) and a mixer (4). The output terminals of the microwave signal source (5) and the noise source (6) are respectively connected to the input terminal of the mixer (4). The output terminal of the mixer (4) is connected to the radio frequency drive terminal of the electro-optic modulator (3). The noise source (6) is used to output a Gaussian white noise signal, and the microwave signal source (5) is used to output a microwave signal with a frequency equal to the Brillouin frequency shift.

4. The fast BOTDA sensing device based on noise chirp modulation according to claim 3, characterized in that, The Gaussian white noise signal output by the noise source (6) has a bandwidth greater than 300MHz and an amplitude greater than 20dBm.

5. A fast BOTDA sensing device based on noise chirp modulation according to claim 1, characterized in that, The electro-optic modulator (3) is used to perform carrier suppression modulation on the first beam to obtain two sidebands with a frequency shift equal to the Brillouin frequency shift, and to achieve spectral broadening of the first beam.

6. The fast BOTDA sensing device based on noise chirp modulation according to claim 1, characterized in that, The electro-optic modulator (3) is used to modulate the first beam to achieve a frequency shift equal to the Brillouin frequency shift, and to achieve a spectrum broadening with a spectral width range of 200-300MHz.

7. A fast BOTDA sensing device based on noise chirp modulation according to claim 1, characterized in that, It also includes a pulse generator (8), the output of which is connected to the electrical drive terminals of the first semiconductor optical amplifier (7) and the second semiconductor optical amplifier (11) respectively, for synchronously driving the first semiconductor optical amplifier (7) and the second semiconductor optical amplifier (11) to perform pulse modulation.

8. A fast BOTDA sensing device based on noise chirp modulation according to claim 2, characterized in that, The first port of the first circulator (9) is connected to the output of the first semiconductor optical amplifier (7), the second port is connected to the input of the chirped Bragg fiber grating (10), and the third port is connected to one end of the sensing fiber (14); the first port of the second circulator (13) is connected to the output of the polarizer (12), the second port is connected to the other end of the sensing fiber (14), and the third port is connected to the input of the filter (15).

9. A fast BOTDA sensing device based on noise chirp modulation according to claim 1, characterized in that, The narrow linewidth laser (1) is a laser with a linewidth of less than 10 kHz, and the dispersion coefficient of the chirped Bragg fiber grating (10) is greater than -5000 ps / nm.

10. A fast BOTDA sensing method based on noise chirp modulation, implemented using the sensing device according to any one of claims 1-9, characterized in that, Includes the following steps: S1. Start the device to cause stimulated Brillouin scattering of the probe light and pump light in the sensing fiber (14); S2. Collect Stokes light or anti-Stokes light signals carrying Brillouin scattering through the data acquisition and analysis system (17); S3. Process the acquired signal, reconstruct the Brillouin gain spectrum by analyzing the time-domain waveform, and demodulate the temperature or strain distribution information along the sensing fiber based on the Brillouin gain spectrum.

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