Brillouin sensing device based on optical parallel differential pulse pairs and working method

Abstract

The application discloses a Brillouin sensing device based on optical parallel differential pulse pairs and a working method, and belongs to the technical field of optical fiber sensing. In view of the problem that the prior art is difficult to consider high resolution, high precision and fast measurement, the device used by the application comprises: an optical source module, which is used to generate an optical carrier; a first optical path module, which is connected with the optical source module and is used to receive the optical carrier and generate optical parallel differential pulse pairs containing anti-Stokes and Stokes components and having different pulse lengths as pump light through double-frequency double-sideband pulse modulation; a second optical path module, which is connected with the optical source module and is used to generate double-sideband probe light; and a sensing optical fiber, which is connected with the first and second optical path modules respectively and is used to receive the pump light and the probe light and directly complete signal differentiation in the optical domain through stimulated Brillouin scattering. Thus, high resolution, high precision and fast measurement are synergistically optimized, the gain / loss mechanism can be flexibly switched, and the scene adaptability is enhanced.

Description

Technical Field

[0001] This invention relates to the field of fiber optic sensing technology, and in particular to a Brillouin sensing device and its operating method based on optical parallel differential pulse pairs. Background Technology

[0002] The statements in this section are merely to provide background information related to the present invention and do not necessarily constitute prior art.

[0003] In structural health monitoring of infrastructure such as large bridges, long-distance oil and gas pipelines, underground energy storage chambers, and high-voltage power cables, distributed fiber optic sensing technology is widely used due to its advantages of being resistant to electromagnetic interference, corrosion resistant, and capable of long-distance continuous measurement.

[0004] Furthermore, while Brillouin optical time-domain analyzers based on stimulated Brillouin scattering can measure temperature or strain, existing Brillouin optical time-domain analysis techniques face the following problems: spatial resolution is determined by the pump pulse width. To improve the resolution of centimeter-level local anomalies, narrow pulses are required, which leads to a decrease in measurement accuracy; conversely, using wide pulses to ensure accuracy reduces spatial resolution, blurs subtle defects, and may even miss risk points. Although traditional differential pulse pairing schemes improve spatial resolution to some extent, they employ a serial pulse measurement mode, requiring pulses of different widths to be injected into the fiber twice and signals to be acquired separately, followed by differential calculations by a computer. This method doubles the measurement time and introduces data processing errors. Weak differential components in the signal are easily submerged by noise, making it difficult to truly meet the engineering requirements of high resolution, high accuracy, and rapid measurement. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a Brillouin sensing device and its operating method based on optical parallel differential pulse pairs. By using dual-frequency double-sideband pulse modulation, the same light source is divided into two paths: the upper path generates optical parallel differential pulse pairs containing anti-Stokes and Stokes components with unequal pulse durations as pump light, and the lower path generates double-sideband probe light; the two lights are injected into the sensing fiber in opposite directions, allowing the probe light to directly perform differential operations on the Brillouin signal in the optical domain without the need for post-processing software, thereby simultaneously achieving high spatial resolution, high measurement accuracy, and rapid measurement.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: In a first aspect, the present invention provides a Brillouin sensing device based on optical parallel differential pulse pairs, comprising a light source module, a first optical path module, a second optical path module, and a sensing fiber. The light source module is used to generate optical carrier waves; The first optical path module is connected to the light source module and is used to receive the optical carrier and generate an optical parallel differential pulse pair containing anti-Stokes and Stokes light components as pump light through dual-frequency double-sideband pulse modulation. The second optical path module is connected to the light source module and is used to generate probe light; The sensing fiber is connected to the first optical path module and the second optical path module respectively, and is used to receive the pump light and the probe light. The signal differential is directly completed in the optical domain through stimulated Brillouin scattering to obtain the differential Brillouin signal. Specifically, the switching between the Brillouin gain mechanism and the Brillouin loss mechanism is achieved by adjusting the pulse duration relationship between the anti-Stokes light component and the Stokes light component in the optical parallel differential pulse pair.

[0007] Preferably, the first optical path module includes: The first polarization controller is used to adjust the polarization state of the optical carrier. Arbitrary waveform generator, used to generate microwave band modulated signals with dual frequencies and unequal durations; An electrical amplifier, connected to an arbitrary waveform generator, is used to amplify microwave band modulated signals; The first electro-optic modulator is connected to the first polarization controller and the electrical amplifier, respectively, and is used to modulate the optical carrier under the drive of the arbitrary waveform generator to generate two sets of optical parallel differential pulse pairs with unequal lengths of dual-frequency double-sideband.

[0008] Preferably, the second optical path module includes: The second polarization controller is used to adjust the polarization state of the optical carrier. A microwave source, used to generate microwave signals; The second electro-optic modulator is connected to the second polarization controller and the microwave source respectively, and is used to modulate the optical carrier under the drive of the microwave source, and output a double-sideband modulated signal as the probe light; A random polarizer, connected to the second electro-optic modulator, is used to polarize the probe light. An optical fiber isolator, connected to a random polarizer, is used to inject the polarized probe light into the sensing optical fiber.

[0009] Preferably, it further includes: a signal processing module connected to the sensing optical fiber, used to process differential signal to obtain distributed sensing information.

[0010] Preferably, the signal processing module includes: The circulator has a first port connected to the first optical path module and a second port connected to the sensing optical fiber, and is used to separate the pump light from the scattered signal. A photodetector, connected to the third port of the circulator, is used to convert the received optical signal into an electrical signal; A data acquisition card, connected to a photodetector, is used to acquire the electrical signals; The host computer is connected to the data acquisition card and is used to process the acquired data to obtain distributed sensing information.

[0011] A second aspect of the present invention provides a method for operating a Brillouin sensing device based on optical parallel differential pulse pairs, comprising: The light carrier emitted by the light source is split into two paths; The first optical carrier is subjected to dual-frequency double-sideband pulse modulation to generate optical parallel differential pulse pairs containing anti-Stokes and Stokes components with unequal pulse durations, which serve as pump light; The second optical carrier is modulated to generate a double-sideband probe light; The pump light and probe light are injected into the sensing fiber, respectively, so that the probe light and the optical parallel differential pulse pair undergo stimulated Brillouin scattering, and the differential operation is directly completed in the optical domain to obtain the differential Brillouin signal. After collecting and processing differentially distributed signals, distributed sensing information is obtained.

[0012] Preferably, the generation process of the optical parallel differential pulse pair is as follows: An arbitrary waveform generator is used to generate a microwave band modulation signal with dual frequencies and unequal durations. After being amplified by an electrical amplifier, the signal drives the first electro-optic modulator to modulate the optical carrier, generating two sets of optical parallel differential pulse pairs with unequal lengths on both sides of the dual frequency.

[0013] Preferably, the step of directly performing the difference operation in the optical domain specifically involves: The anti-Stokes component and the Stokes component in the pump light produce Brillouin gain effect and Brillouin loss effect on the probe light, respectively. During the pulse time overlap period, the gain and loss cancel each other out, and during the differential time period, the net gain or net loss is taken as the differential signal.

[0014] Preferably, it also includes a Brillouin gain-loss dual-mechanism switching: The dual-mechanism switching is achieved by adjusting the pulse duration relationship between the anti-Stokes component and the Stokes component in the optical parallel differential pulse pair. Specifically, when the duration of the anti-Stokes pulse is longer than that of the Stokes pulse, the mechanism switches to Brillouin gain; when the duration of the anti-Stokes pulse is shorter than that of the Stokes pulse, the mechanism switches to Brillouin loss.

[0015] Preferably, when the pulse duration of the anti-Stokes optical component is equal to that of the Stokes optical component, a Brillouin gain mechanism and a Brillouin loss mechanism are generated respectively by introducing a π-phase shift point at the differential start position at the end of the microwave segment.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention generates optically parallel differential pulse pairs containing anti-Stokes and Stokes components through a first optical path module, directly transferring the differential operations of traditional serial time-division acquisition to the optical domain. This eliminates the need for subsequent data processing, significantly improving measurement efficiency and system sampling rate, while avoiding computational errors and quantization noise introduced by software differential processing. Furthermore, the device retains the high spatial resolution advantage of differential pulse pair technology, achieving synergistic optimization of resolution, accuracy, and speed. In addition, by flexibly adjusting the pulse duration relationship between the anti-Stokes and Stokes components, it can freely switch between gain-type and loss-type Brillouin sensing mechanisms without hardware changes, quickly adapting to measurement requirements in different fiber optic sensing scenarios and enhancing the device's scene adaptability. Attached Figure Description

[0017] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0018] Figure 1 This is a schematic diagram of the device according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram illustrating the principle of the Brillouin optical domain parallel differential mechanism of the present invention; Figure 3 This is a schematic diagram illustrating the Brillouin gain-loss dual-mechanism switching principle of the present invention; wherein, Figure 3 (a) in the diagram is a schematic diagram of the pulse width corresponding to the Brillouin gain mechanism. Figure 3 (b) in the diagram is a schematic diagram of the pulse width corresponding to the Brillouin loss mechanism; Figure 4 This is a schematic diagram illustrating the switching principle of the π-phase-shift Brillouin gain-loss dual mechanism of the present invention; wherein, Figure 4 (a) in the diagram is a pulse diagram corresponding to the Brillouin gain mechanism. Figure 4 (b) in the diagram is a pulse diagram corresponding to the Brillouin loss mechanism; Figure 5 This is a schematic diagram of the frequency relationship of the optical parallel differential pulse pairs of the present invention; The components include: 1. Narrow linewidth laser; 2. Fiber optic coupler; 3. First polarization controller; 4. First electro-optic modulator; 5. Electrical amplifier; 6. Arbitrary waveform generator; 7. Erbium-doped fiber amplifier; 8. Circulator; 8-1. Circulator port 1; 8-2. Circulator port 2; 8-3. Circulator optical signal port 3; 9. Photodetector; 10. Sensing fiber; 11. Second polarization controller; 12. Second electro-optic modulator; 13. Microwave source; 14. Random polarization scrambler; 15. Fiber optic isolator; 16. Data acquisition card; 17. Host computer. Detailed Implementation

[0019] The following detailed description is exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0020] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0021] In this embodiment of the invention, the data collection and processing strictly adhere to the requirements of relevant laws and regulations, obtaining informed consent or separate consent from the data subject, and conducting subsequent data use and processing within the scope of laws, regulations, and the data subject's authorization. All data acquisition in this embodiment is based on compliance with laws and regulations and user consent, representing the lawful application of the data.

[0022] Example 1 Taking long-distance oil and gas pipeline leak monitoring as an example: Traditional Brillouin Optical Time Domain Analyzer (BOTDA) technology requires narrow pulses to improve spatial resolution for locating centimeter-level leaks, but this leads to a decrease in measurement accuracy. If wide pulses are used to ensure accuracy, the location of tiny leaks will be blurred. Traditional differential pulse pair schemes can achieve both to some extent, but they require injecting pulses of different widths into the optical fiber twice and acquiring the signals, and then performing differential analysis by a computer. This doubles the time required for a single monitoring, and the quantization noise of the acquisition card can easily drown out weak leak signals, further reducing the signal-to-noise ratio. To address the aforementioned problems of the contradiction between spatial resolution and measurement accuracy, low efficiency of serial acquisition, and data processing errors, this invention divides the same light source into two paths: the upper path uses dual-frequency double-sideband pulse modulation to generate optical parallel differential pulse pairs containing anti-Stokes and Stokes components with unequal pulse durations as pump light, and utilizes the unequal pulse lengths and widths to achieve high resolution of narrow pulses through optical domain differential equivalence; the lower path generates probe light that is injected from the other end. When two beams of light propagate in opposite directions and interact within an optical fiber, the gain-loss interaction of stimulated Brillouin scattering allows for direct differential computation in the optical domain, eliminating the need for two data acquisitions and software post-processing. This enables high spatial resolution, high precision, and fast response in a single measurement, while avoiding quantization noise interference. Furthermore, by adjusting the pulse duration, the gain or loss mechanism can be flexibly switched to adapt to monitoring requirements at different sensing distances.

[0023] In a typical embodiment of the present invention, a high-resolution Brillouin sensing device based on optical parallel differential pulse pairs is provided. The core relies on the Brillouin optical domain parallel differential mechanism to realize direct differential operation in the optical domain, and achieves Brillouin gain-loss dual mechanism switching by adjusting the pulse duration, thus taking into account spatial resolution, measurement accuracy and measurement efficiency.

[0024] like Figure 1 As shown, a Brillouin sensing device based on optical parallel differential pulse pairs is disclosed, comprising: The light source module is used to generate optical carrier waves; The first optical path module, connected to the light source module, is used to receive the optical carrier and generate an optical parallel differential pulse pair as pump light through dual-frequency double-sideband pulse modulation; the optical parallel differential pulse pair includes an anti-Stokes light component and a Stokes light component generated simultaneously within the same optical pulse, and the pulse durations of the two components are different. The second optical path module is connected to the light source module and is used to receive the optical carrier and generate probe light; The sensing fiber is connected to the first optical path module and the second optical path module respectively, and is used to receive the pump light and the probe light, so that the probe light and the optical parallel differential pulse pair in the fiber undergo stimulated Brillouin scattering, and the differential operation of the Brillouin signal is directly completed in the optical domain to obtain the differential Brillouin signal. The signal processing module, connected to the sensing optical fiber, is used to acquire and process the differential Lyovan signal to obtain distributed temperature and strain sensing information.

[0025] Specifically, the light source module is a narrow linewidth laser 1 that emits an optical carrier in the 1550nm band. The carrier is split into two paths by an optical fiber coupler 2. The upper branch generates a parallel differential pulse pump light, and the lower branch generates a probe light.

[0026] The upper optical path passes through a first polarization controller 3 to adjust the polarization state of the optical carrier. An arbitrary waveform generator 6 generates a series of dual-frequency, unequal-duration microwave-band modulated optical carriers, which are amplified by an electrical amplifier 5 and then drive a first electro-optic modulator 4 to generate two sets of parallel differential pulse pairs. The electrical amplifier, connected to the arbitrary waveform generator, amplifies the microwave-band modulated signal. The first electro-optic modulator, connected to both the first polarization controller and the electrical amplifier, modulates the optical carriers with both intensity and frequency under the drive of the arbitrary waveform generator, generating two sets of optically parallel differential pulse pairs with unequal dual-frequency double-sideband lengths. The parallel differential pulse pairs pass through an erbium-doped fiber amplifier 7, are input through port 8-1 of a circulator 8, and output through port 8-2 of the circulator into the sensing fiber 10.

[0027] In the lower branch, after passing through the second polarization controller 11 (used to adjust the polarization state of the optical carrier), a microwave signal is generated by the microwave source 13 to drive the second electro-optic modulator 12 to output a double-sideband modulated signal as the probe light. The second electro-optic modulator 12 is connected to both the second polarization controller and the microwave source, and is used to modulate the optical carrier under the drive of the microwave source, outputting a double-sideband modulated signal as the probe light. Subsequently, the probe light passes through a random polarizer 14, which is connected to the second electro-optic modulator, to scramble the probe light. Finally, it passes through an optical fiber isolator 15, which is connected to the random polarizer, to isolate the reverse light and inject the scrambled probe light into the sensing optical fiber 10.

[0028] The signal processing module includes: a circulator, with its first port connected to a first optical path module and its second port connected to a sensing optical fiber, for separating pump light and scattered signals; a photodetector, connected to the third port of the circulator, for converting the received optical signal into an electrical signal; a data acquisition card, connected to the photodetector, for acquiring the electrical signal; and a host computer, connected to the data acquisition card, for processing the acquired data to obtain distributed sensing information.

[0029] Specifically, the circulator's third optical signal port 8-3 is connected to the optical signal input of the photodetector 9, and the electrical signal output of the photodetector 9 is connected to the electrical signal input of the data acquisition card 16. The data acquisition card 16 acquires the data from the sensing fiber 10, and the host computer 17 uses the Lorentz curve fitting algorithm to fit the obtained Brillouin gain spectrum or loss spectrum to obtain the Brillouin frequency shift, thereby obtaining high-precision distributed temperature or strain information.

[0030] Taking long-distance oil and gas pipeline leak monitoring as an example, traditional serial differential pulse pair schemes require injecting two pulses of different widths into the optical fiber and acquiring signals separately. This means that the same leak point on the same pipeline must be "measured twice," doubling the measurement time. Furthermore, during the interval between the two measurements, fluctuations in ambient temperature or changes in pipeline strain can lead to inconsistent background noise in the two acquired signals, introducing new errors during subsequent computer subtraction. This invention employs two sets of optical parallel differential pulse pairs, using dual-frequency double-sideband modulation technology to merge two pulses of different widths and frequencies into a single optical pulse, effectively compressing "two measurements" into "one measurement." These two pulse pairs interact simultaneously with the probe light in the optical fiber, utilizing the physical cancellation mechanism of gain and loss to directly perform differential analysis in the optical domain. This eliminates the need for a second acquisition and subsequent software differential calculations, doubling the measurement efficiency while avoiding interference from environmental changes and quantization noise, ensuring accurate identification of even minute leak points in rapidly changing environments.

[0031] The specific method for generating optical parallel differential pulse pairs is as follows: The arbitrary waveform generator 6 outputs a microwave modulation signal with dual frequencies and unequal durations. After being amplified by the electrical amplifier 5, it drives the first electro-optic modulator 4 to perform intensity and frequency joint modulation on the optical carrier, generating two sets of optical parallel differential pulse pairs with unequal lengths on both sides of the dual frequency.

[0032] By adjusting the pulse duration relationship between the anti-Stokes and Stokes components in the optical parallel differential pulse pair, the Brillouin gain mechanism and the Brillouin loss mechanism can be freely switched. Specifically, when the anti-Stokes pulse duration is longer than the Stokes pulse duration, the Brillouin gain mechanism is used; when the anti-Stokes pulse duration is shorter than the Stokes pulse duration, the Brillouin loss mechanism is used.

[0033] Specifically, the Brillouin gain-loss dual-mechanism switching: The pulse width and timing of the dual-frequency microwave signal can be directly adjusted using the arbitrary waveform generator 6, thereby changing the pulse duration relationship between the inverse Stokes component and the Stokes component. Lengthen the anti-Stokes pulse, shorten the Stokes pulse, and switch to the Brillouin gain mechanism; Shorten the anti-Stokes pulse and lengthen the Stokes pulse to switch to the Brillouin loss mechanism. Adjust the pulse duration difference according to the required spatial resolution, and the dual-mechanism switching can be completed quickly without changing hardware or recalibrating the optical path.

[0034] Taking oil and gas pipeline monitoring as an example, the monitoring distance is the core factor determining the selection of the Brillouin sensing mechanism, requiring a dynamic adaptation to the optimal mechanism based on distance. For short-distance pipelines, pump power attenuation along the pipeline is limited, and the signal-to-noise ratio is sufficient. The Brillouin gain mechanism can achieve high-precision temperature and strain distribution measurements, meeting pipeline safety monitoring requirements. However, for long-distance pipelines, accumulated link losses lead to a significant decrease in the signal-to-noise ratio. Simultaneously, nonlinear problems such as pump cavitation and nonlocal effects become increasingly prominent with increasing distance. In this case, a switch to the Brillouin loss mechanism should be made, leveraging its advantages of insensitivity to pump depletion and better linearity along the pipeline to ensure the accuracy and consistency of monitoring throughout the entire process, thereby achieving reliable perception of the condition along long-distance oil and gas pipelines. This invention flexibly adjusts the pulse duration relationship between the anti-Stokes and Stokes beams in an optical parallel differential pulse pair: lengthening the anti-Stokes pulse and shortening the Stokes pulse switches to a gain mechanism to obtain a strong signal; conversely, it switches to a loss mechanism to suppress noise and improve the detection capability of weak signals. This means that in monitoring the same pipeline traversing different geological conditions, operators do not need to change any hardware; they can dynamically switch the optimal sensing mechanism for different pipeline sections simply by adjusting the pulse duration through software, significantly improving adaptability and measurement reliability in complex scenarios.

[0035] The working principle is as follows: 1. Principle of Brillouin Optical Domain Parallel Differential Mechanism Optical parallel differential pulse pairs will produce a set of dual-frequency unequal-length pump pulses ( , ), performing differential operations in the optical domain through a Brillouin gain-loss dual mechanism; such as Figure 2 As shown, the principle is explained using a gain-type optical parallel differential pulse pair. During the sensing process, the pump pulse light contains anti-Stokes light. ) and Stokes light Their time lengths are respectively ( Its length typically needs to be greater than 40 ns to ensure stable establishment of the acoustic field. Its pulse width difference is set according to the spatial resolution requirements; when the system requires a gain mechanism and the spatial resolution is 10 cm, then... Nanoseconds. When the system requires a lossy mechanism and a spatial resolution of 10 cm, then... Nanosecond. Its frequency is The frequency relationship can be expressed as: (1) Stimulated Brillouin scattering produces two frequency components. Dynamic grating, typically 10.85 GHz. To detect the frequency of light, it is represented as: . This is the laser frequency, with a typical wavelength of 1550nm. This is the sweep frequency (typically 200MHz). L is the fiber length. For the probe light, in front... During this time period, both Brillouin gain and loss occurred simultaneously, with the gain and loss exactly canceling each other out. However, afterwards... During the time interval, the probe light still receives gain from the anti-Stokes pump pulse, thus enabling parallel differential optical domain operation. This can be achieved by directly... Frequency sweeping yields the complete distributed differential distribution Leyen gain spectrum.

[0036] 2. Brillouin gain-loss dual-mechanism switching principle like Figure 3 As shown, when generating differential pulse pairs, flexible switching between the Brillouin gain-loss dual mechanism is achieved simply by adjusting the pulse duration; where, as Figure 3 As shown in (a), the duration of the dual-frequency unequal-length pump pulse light is set to... When the probe light experiences Brillouin gain for a longer period than it experiences Brillouin loss, the pulse difference... The generation of a Brillouin signal with a gain-type difference distribution within a time range is a Brillouin gain mechanism. For example... Figure 3 As shown in (b), when When the time during which the probe light experiences Brillouin gain is shorter than the time during which it experiences Brillouin loss, a loss-type differential distribution Brillouin signal can be realized in the optical domain, which is the Brillouin loss mechanism.

[0037] like Figure 4 The diagram shown illustrates the switching principle of the π-phase-shift Brillouin gain-loss dual-mechanism of this invention; wherein, Figure 4 (a) in the diagram is a pulse diagram corresponding to the Brillouin gain mechanism. Figure 4 (b) in the diagram shows the pulse diagram corresponding to the Brillouin loss mechanism. When the differential pulse pairs can also be of equal duration... ,like Figure 4 Image (a) shows the Brillouin gain mechanism, which uses an arbitrary waveform generator to generate a function. Microwave signals, in There is no phase transition within a time period, and the function is , microwave signals in There is no phase jump within the differential phase, but a π-phase shift point is introduced at the beginning of the differential phase, resulting in a phase of... When they are in phase, the Brillouin gain and loss produced by the two cancel each other out, while... Within the differential range, the probe light experiences a Brillouin gain and a doubling of the Brillouin gain due to coherent anti-Stokes scattering. For example... Figure 4 Figure (b) shows the Brillouin loss mechanism, which uses an arbitrary waveform generator to generate a function. Microwave signals, in There is no phase transition within a time period, and the function is , microwave signals in There is no phase jump within the differential phase, but a π-phase shift point is introduced at the beginning of the differential phase, resulting in a phase of... When they are in phase, the Brillouin gain and loss produced by the two cancel each other out, while... Within the differential pulse range, the probe light experiences Brillouin loss and doubles the Brillouin loss due to coherent Stokes scattering. Therefore, within the differential pulse range, the signal-to-noise ratio of the differential Brillouin time-domain signal is doubled.

[0038] like Figure 5 The diagram shown illustrates the frequency relationship of the optical parallel differential pulse pairs of this invention; optical carrier. Fixed upshift frequency Frequency, as probe light The optical differential pulse pairs P1 and P2 have pulse widths of t1 and t2, respectively, and the frequencies of their +1 and -1 sidebands are V, respectively. P1 and V P2 When the optical differential pulse pair is with V S Frequency difference is V B1 =VB2 When the Brillouin scattering effect occurs, stimulated Brillouin scattering (SBS) occurs. When the Brillouin gain mechanism is used, the Brillouin gain spectrum (BGS) is measured. When the Brillouin loss mechanism is used, the Brillouin loss spectrum (BLS) is measured.

[0039] Example 2 In a typical embodiment of the present invention, a method for operating a Brillouin sensing device based on optical parallel differential pulse pairs is provided, comprising: Step 1: Split the light carrier emitted by the light source into two paths; Step 2: Perform dual-frequency double-sideband pulse modulation on the first optical carrier to generate optical parallel differential pulse pairs containing anti-Stokes and Stokes components with unequal pulse durations, which serve as pump light; Step 3: Modulate the second optical carrier to generate double-sideband probe light; Step 4: Inject the pump light and probe light into the sensing fiber respectively, so that the probe light and the optical parallel differential pulse pair undergo stimulated Brillouin scattering, and the differential operation of the Brillouin signal is directly completed in the optical domain to obtain the differential Brillouin signal. Step 5: Collect differentially distributed aurora signals and process them to obtain distributed sensing information.

[0040] The generation process of optical parallel differential pulse pairs is as follows: An arbitrary waveform generator is used to generate a microwave band modulation signal with dual frequencies and unequal durations. After being amplified by an electrical amplifier, the signal drives the first electro-optic modulator to modulate the optical carrier, generating two sets of optical parallel differential pulse pairs with unequal lengths on both sides of the dual frequency.

[0041] The difference operation of Brillouin signals is performed directly in the optical domain, specifically as follows: The anti-Stokes component and the Stokes component in the pump light produce Brillouin gain effect and Brillouin loss effect on the probe light, respectively. During the pulse time overlap period, the gain and loss cancel each other out; during the differential period... The net gain or net loss is used as the differential distribution Lieyuan signal.

[0042] The overlap period refers to the time when two pulses exist simultaneously, and its function is to cancel out signals; the differential period refers to the time when a long pulse exists alone, and its function is to output a net signal, which is the key to achieving high resolution.

[0043] It also includes Brillouin gain-loss dual-mechanism switching: The dual-mechanism switching is achieved by adjusting the pulse duration relationship between the anti-Stokes component and the Stokes component in the optical parallel differential pulse pair. Specifically, when the duration of the anti-Stokes pulse is longer than that of the Stokes pulse, the mechanism switches to Brillouin gain; when the duration of the anti-Stokes pulse is shorter than that of the Stokes pulse, the mechanism switches to Brillouin loss.

[0044] When the pulse duration of the anti-Stokes optical component is equal to that of the Stokes optical component, a Brillouin gain mechanism and a Brillouin loss mechanism are generated respectively by introducing a π-phase shift point at the differential start position at the end of the microwave segment.

[0045] This invention splits the optical carrier emitted by the light source into two paths. The first optical carrier is modulated with dual-frequency double-sideband pulses to generate an optically parallel differential pulse pair containing both anti-Stokes and Stokes components with unequal pulse durations, serving as the pump light. The second optical carrier is modulated to generate a double-sideband probe light. The pump light and probe light are injected into the sensing fiber, causing stimulated Brillouin scattering between the probe light and the parallel differential pulse pair. Utilizing the mechanism that the gain effect of the anti-Stokes component on the probe light and the loss effect of the Stokes component on the probe light cancel each other out during the pulse time overlap period, outputting a net gain or net loss during the differential time period, the differential operation of the Brillouin signal is directly performed in the optical domain to obtain the differential Brillouin signal. After acquiring and processing this signal, distributed temperature and strain sensing information is obtained. This transforms the traditional serial electrical domain differential operation into a parallel optical domain direct differential operation, achieving a synergistic optimization of high spatial resolution, high measurement accuracy, and fast measurement.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0047] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A Brillouin sensing device based on optical parallel differential pulse pairs, characterized in that, It includes a light source module, a first optical path module, a second optical path module, and a sensing fiber; The light source module is used to generate optical carrier waves; The first optical path module is connected to the light source module and is used to receive the optical carrier and generate an optical parallel differential pulse pair containing anti-Stokes and Stokes light components as pump light through dual-frequency double-sideband pulse modulation. The first optical path module includes: a first polarization controller for adjusting the polarization state of the optical carrier; an arbitrary waveform generator for generating a microwave band modulation signal with dual frequencies and unequal durations; an electrical amplifier connected to the arbitrary waveform generator for amplifying the microwave band modulation signal; and a first electro-optic modulator connected to the first polarization controller and the electrical amplifier, respectively, for modulating the optical carrier under the drive of the arbitrary waveform generator to generate two sets of optical parallel differential pulse pairs with unequal lengths on both sides of the dual frequency. The second optical path module, connected to the light source module, is used to generate probe light. The second optical path module includes: a second polarization controller for adjusting the polarization state of the optical carrier; a microwave source for generating microwave signals; a second electro-optic modulator connected to both the second polarization controller and the microwave source, used to modulate the optical carrier under the drive of the microwave source and output a double-sideband modulated signal as probe light; a random polarization scrambler connected to the second electro-optic modulator for scrambling the probe light; and an optical fiber isolator connected to the random polarization scrambler for injecting the scrambled probe light into the sensing optical fiber. The sensing fiber is connected to the first optical path module and the second optical path module respectively, and is used to receive the pump light and the probe light. The signal differential is directly completed in the optical domain through stimulated Brillouin scattering to obtain the differential Brillouin signal. It also includes: a signal processing module for processing differentially distributed scattering signals to obtain distributed sensing information; the signal processing module includes: a circulator, whose first port is connected to a first optical path module and its second port is connected to a sensing optical fiber, for separating pump light and scattered signals; a photodetector, connected to the third port of the circulator, for converting the received optical signal into an electrical signal; a data acquisition card, connected to the photodetector, for acquiring the electrical signal; and a host computer, connected to the data acquisition card, for processing the acquired data to obtain distributed sensing information; Specifically, the switching between the Brillouin gain mechanism and the Brillouin loss mechanism is achieved by adjusting the pulse duration relationship between the anti-Stokes light component and the Stokes light component in the optical parallel differential pulse pair.

2. A method of operating a Brillouin sensing device based on optical parallel differential pulse pairs, using a Brillouin sensing device based on optical parallel differential pulse pairs as claimed in claim 1, characterized in that, include: The light carrier emitted by the light source is split into two paths; The first optical carrier is subjected to dual-frequency double-sideband pulse modulation to generate optical parallel differential pulse pairs containing anti-Stokes and Stokes components with unequal pulse durations, which serve as pump light; The second optical carrier is modulated to generate a double-sideband probe light; The pump light and probe light are injected into the sensing fiber, respectively, so that the probe light and the optical parallel differential pulse pair undergo stimulated Brillouin scattering, and the differential operation is directly completed in the optical domain to obtain the differential Brillouin signal. After collecting and processing differentially distributed signals, distributed sensing information is obtained.

3. The operating method of the Brillouin sensing device based on optical parallel differential pulse pairs as described in claim 2, characterized in that, The generation process of the optical parallel differential pulse pair is as follows: An arbitrary waveform generator is used to generate a microwave band modulation signal with dual frequencies and unequal durations. After being amplified by an electrical amplifier, the signal drives the first electro-optic modulator to modulate the optical carrier, generating two sets of optical parallel differential pulse pairs with unequal lengths on both sides of the dual frequency.

4. The operating method of the Brillouin sensing device based on optical parallel differential pulse pairs as described in claim 2, characterized in that, The specific steps for performing the difference operation directly in the optical domain are as follows: The anti-Stokes component and the Stokes component in the pump light produce Brillouin gain effect and Brillouin loss effect on the probe light, respectively. During the pulse time overlap period, the gain and loss cancel each other out, and during the differential time period, the net gain or net loss is taken as the differential signal.

5. The operating method of the Brillouin sensing device based on optical parallel differential pulse pairs as described in claim 2, characterized in that, It also includes Brillouin gain-loss dual-mechanism switching: The dual-mechanism switching is achieved by adjusting the pulse duration relationship between the anti-Stokes component and the Stokes component in the optical parallel differential pulse pair. Specifically, when the duration of the anti-Stokes pulse is longer than that of the Stokes pulse, the mechanism switches to Brillouin gain; when the duration of the anti-Stokes pulse is shorter than that of the Stokes pulse, the mechanism switches to Brillouin loss.

6. The operating method of the Brillouin sensing device based on optical parallel differential pulse pairs as described in claim 5, characterized in that, When the pulse duration of the anti-Stokes optical component is equal to that of the Stokes optical component, a Brillouin gain mechanism and a Brillouin loss mechanism are generated respectively by introducing a π-phase shift point at the differential start position at the end of the microwave segment.

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