A distributed optical fiber sensing and transmission method and system based on optical grouping

Abstract

A distributed optical fiber sensing and transmission method and system based on optical grouping integrates the concepts of signal frames and signal elements in the communication field into the sensing field. Each measurement signal frame contains several measurement signal elements to achieve full-fiber scanning. Each measurement signal element contains a pair of time-coded pump light pulses and rectangular square wave detection light. The two are injected into the optical fiber in the same direction. After the detection light is reflected at the end of the optical fiber, it meets the pump light in the opposite direction, generating a scattered signal. Analysis of this signal can achieve the measurement of the encounter point. Because the pulse square wave time intervals in each measurement signal element are different, the constructed measurement signal frame can cover all measurement points on the optical fiber, thereby achieving the goal of full-fiber distributed measurement. The present invention avoids the pump light emptying effect and non-local effect, and can complete the measurement of all points at once while ensuring resolution (spatial resolution and measurement accuracy), taking into account both resolution and time efficiency.

Description

Technical Field

[0001] The present invention relates to distributed optical fiber sensing, and in particular to a distributed optical fiber sensing and transmission method and system based on optical grouping. Background Art

[0002] Sensing technology is widely used to measure various physical quantities, such as strain, temperature, and pressure. Fiber optic sensing technology, with its high sensitivity and strong resistance to electromagnetic interference, is becoming increasingly important in intelligent monitoring systems. Fiber optic sensing technology is broadly categorized as point sensing and distributed sensing, each offering distinct application advantages.

[0003] Point sensing technologies, such as fiber Bragg grating (FBG) sensors, offer the advantages of high precision and high sensitivity, but their discrete measurement points make it difficult to achieve continuous spatially distributed measurements. Furthermore, when large-scale deployment is required, the complexity and cost of point sensing systems increase significantly.

[0004] In contrast, distributed fiber optic sensing technology utilizes the entire length of an optical fiber as a sensing element, enabling continuous spatial distribution measurement of the measured parameter along its length. However, current distributed fiber optic sensing technology faces a trade-off between resolution and time efficiency. Specifically, to improve spatial resolution, pulse width compression is often necessary, but this reduces the system's signal-to-noise ratio and, in turn, measurement accuracy. To maintain sufficient measurement accuracy, the number of repeated measurements must be increased, inevitably sacrificing the system's time efficiency.

[0005] The academic community has also conducted in-depth research on this issue. For example, in the article "High spatial resolution, low-noise Brillouin dynamic gratings reflectometry based on digital pulse compression" published by Bergman et al. in "Optics Letters" in 2016 and the article "Enhancing the performance of BOTDR based on the combination of FFT technique and complementary coding" published by Wang et al. in "Optics Express" in 2017, it was mentioned that although shortening the pulse width can effectively improve the spatial resolution, this will significantly reduce the signal-to-noise ratio, and thus require an increase in the number of repeated measurements to obtain acceptable measurement accuracy, resulting in a significant reduction in the time efficiency of the system. To address this problem, patent CN101852627A (Coding technology and its use for improving the detection performance of distributed optical fiber sensors) uses coding technology to improve the signal-to-noise ratio, thereby reducing the number of repeated measurements and shortening the measurement time. However, when the coding order is too high, the effect of this method in shortening the system measurement time is also limited, and further technological innovation is still needed to break through the current limitations. Summary of the Invention

[0006] In response to the shortcomings of the existing technology, the present invention proposes a distributed optical fiber sensing and transmission method based on optical packetization. The idea of ​​improving network bandwidth utilization by using signal frames and signal elements in the communication field is introduced into the sensing field to improve sensing efficiency. Each measurement signal frame is constructed as a composite unit containing several measurement signal elements. These signal elements work together to realize all-fiber distributed scanning measurement. Each measurement signal element is a pair of pulse square wave combinations, including a pump light pulse with a specific time encoding and a rectangular square wave-shaped detection light. At each measurement point, when the pump light and the detection light meet at a certain position in the optical fiber, they can induce a stimulated Brillouin scattering effect. By analyzing the scattered signal, the sensing information of that point can be obtained, realizing single-point measurement. Since the pulse square wave time intervals within each measurement signal element are different, the constructed measurement signal frame can cover all measurement points on the optical fiber, thereby realizing all-fiber distributed high-precision measurement.

[0007] The technical solutions adopted by the present invention are as follows:

[0008] A distributed optical fiber sensing and transmission method based on optical grouping is characterized by using measurement signal frames to achieve full-fiber scanning measurement, wherein each measurement signal frame contains several measurement signal elements, each measurement signal element is used to sense a specific measurement point in the optical fiber; the measurement signal element includes a pump light and a probe light, and the pump light and the probe light have a specific time delay relationship between them, which is used to generate a nonlinear scattering effect at a predetermined measurement point in the optical fiber.

[0009] Measuring principle:

[0010] 1) Optical signal injection: High-power pump light and rectangular square wave probe light are injected into the optical fiber in the same direction but not at the same time. The probe light is reflected by the fiber Bragg grating at the end of the optical fiber and becomes the reverse probe light.

[0011] 2) SBS generation: When the reverse probe light and the forward pump pulse light meet in the optical fiber and meet the phase matching condition, a reverse Brillouin scattering pulse is generated.

[0012] 3) Signal detection: The generated Brillouin scattering signal is captured and processed by the detection system, thereby enabling measurement of specific locations along the optical fiber.

[0013] On the one hand, the present invention provides a distributed optical fiber sensing and transmission method based on optical grouping, which is characterized in that a measurement signal frame is used to realize full-fiber scanning measurement, wherein each measurement signal frame contains a plurality of measurement signal elements, and each measurement signal element is used to sense a specific measurement point in the optical fiber; the measurement signal element includes a pump light and a probe light, and the pump light and the probe light have a specific time delay relationship between them, which is used to generate a nonlinear scattering effect at a predetermined measurement point in the optical fiber.

[0014] Furthermore, the pump light is a high-power, narrow-width pulse, and the detection light is a rectangular square wave signal.

[0015] Furthermore, the pump light and the probe light are injected into the optical fiber in the same direction but not at the same time. The probe light is reflected by the fiber Bragg grating at the end of the optical fiber and becomes reverse probe light, propagating in the opposite direction of the pump light and meeting at a predetermined measurement point in the optical fiber to cause nonlinear scattering, including Brillouin scattering or Raman scattering.

[0016] Furthermore, the time delay intervals between the pump light pulse and the detection light signal within each measurement signal element are different, so that the constructed measurement signal frame can cover all measurement points on the optical fiber, realizing full-fiber distributed measurement.

[0017] Furthermore, the relationship between the duration T0 of the measurement signal frame and the duration τ0 of the measurement signal element is determined by the following formula:

[0018] T0=m*τ0;

[0019] Where m is the number of measurement points in the optical fiber.

[0020] Furthermore, the number of measurement points m in the optical fiber, the total length L0 of the optical fiber, and the spatial resolution l0 satisfy the following relationship:

[0021]

[0022] Furthermore, the duration τ0 of the measurement signal element is related to the total length L0 of the optical fiber and the group velocity v g The following relationship is satisfied:

[0023]

[0024] Furthermore, the time delay τ between the pump light and the probe light is i With the measured point P i Distance L i The following relations are satisfied:

[0025]

[0026] Among them, L i From the fiber entrance to the measured point P i distance.

[0027] Furthermore, the distributed optical fiber sensing and transmission method based on optical grouping includes the following steps:

[0028] Generate stable, high-quality continuous light and divide it into pump light path and detection light path;

[0029] Modulating the pump light and the probe light to generate a measurement signal element including a high-power pump pulse and a rectangular square wave probe light;

[0030] Control the time delay between pump light and probe light;

[0031] Power amplification and polarization optimization of pump light and probe light;

[0032] Combine the pump light and the detection light and inject them into a single-mode single-core optical fiber;

[0033] At the fiber Bragg grating at the end of the optical fiber, the probe light is reflected and propagates in opposite directions with the pump light, and they meet at a predetermined position in the optical fiber and undergo stimulated Brillouin scattering.

[0034] The signal acquisition and processing module is used to collect and process the reverse propagating Brillouin scattering signal to obtain the sensing quantity of the measurement point in the optical fiber.

[0035] On the other hand, the present invention also provides a distributed optical fiber sensing and transmission system based on optical grouping, which is characterized by including:

[0036] Laser and optical signal generation module, used to generate stable, high-quality continuous light and divide it into pump light path and detection light path;

[0037] An optical signal modulation and control module, which is used to modulate the pump light and probe light to generate a measurement signal element containing a high-power pump pulse and a rectangular square wave probe light; it includes a nanosecond pulse generator and encoding module for pulse modulation of the pump light, and a 10 GHz microwave source and encoding module for modulating the probe light;

[0038] A central control module is used to control the time delay between the pump light and the probe light so that they meet at a predetermined position in the optical fiber and generate a stimulated Brillouin scattering effect;

[0039] The optical signal amplification and optimization control module includes an erbium-doped fiber amplifier and a polarization controller, which is used to amplify the power and optimize the polarization of the pump light and the probe light;

[0040] Optical signal combining and injection fiber module, including a 2*1 coupler and a circulator, is used to combine pump light and detection light and inject them into a single-mode single-core fiber;

[0041] Fiber sensing and stimulated Brillouin scattering module, including a fiber Bragg grating at the end of the optical fiber, used to reflect the probe light and make it propagate in the opposite direction of the pump light;

[0042] The signal acquisition and processing module, including the optoelectronic processing module and the data server, is used to collect the reverse-propagating Brillouin scattering signal and process it to obtain the sensing quantity of the measurement point in the optical fiber;

[0043] The measurement signal elements are arranged sequentially in the time domain to form a measurement signal frame covering the entire length of the optical fiber. By adjusting the time delay between the pump light and the probe light, their encounter at a certain position in the optical fiber can be controlled.

[0044] Compared with the prior art, the present invention has the following advantages:

[0045] 1) By adjusting the pulse width and amplitude, the spatial resolution and signal-to-noise ratio are optimized. Under the premise of ensuring resolution, the measurement of all measurement points of the optical fiber is completed at one time, taking into account both resolution and time efficiency. This method significantly improves the measurement time efficiency while taking into account high resolution, providing strong support for fast and accurate distributed optical fiber sensing.

[0046] 2) In traditional fiber-optic sensing technology, pump light depletion and non-local effects often adversely affect measurement results. This invention successfully avoids these effects by optimizing pulse parameters and signal encoding, thereby ensuring the accuracy and reliability of measurement results.

[0047] 3) The single-ended injection method avoids the need to arrange a light source at the other end of the optical fiber, reducing hardware costs. In practical applications, since the other end of the optical fiber can be freely arranged, the system can be used in scenarios with complex environments or where the optical fiber end is difficult to access (such as submarine cable monitoring, earthquake monitoring, etc.).

[0048] 4) This invention allows users to precisely control the spatial resolution and measurement accuracy of measurement points by flexibly adjusting pulse parameters (such as pulse width and time interval) based on actual needs. This feature enables the invention to achieve high-resolution and high-precision measurements in a variety of application scenarios. Furthermore, the ability to simultaneously measure all points on the optical fiber further improves measurement efficiency and meets diverse and complex measurement needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A schematic diagram of a measurement signal frame provided by an embodiment of the present invention.

[0050] Figure 2 A schematic diagram of a measurement signal element provided by an embodiment of the present invention.

[0051] Figure 3 A schematic diagram of the application of the distributed optical fiber sensing and transmission method based on optical grouping provided in an embodiment of the present invention.

[0052] Figure 4 is the i-th measurement signal element τ i Schematic diagram of the measurement timing.

[0053] 1: Measurement signal frame

[0054] 2: Measurement signal element

[0055] 3: High-power pump pulses

[0056] 4: Rectangular square wave detection light

[0057] 5: Single-mode single-core optical fiber

[0058] 6: 1*2 coupler

[0059] 7: Modulator

[0060] 8: Erbium-doped Optical Fiber Amplifier (EDFA)

[0061] 9: Polarization controller (PC)

[0062] 10: 2*1 coupler

[0063] 11: Circulator

[0064] 12: Fiber Bragg Grating

[0065] 13: Narrow linewidth wavelength tunable laser

[0066] 14:ns pulse generator and encoding module

[0067] 15: 10GHz microwave source and encoding module

[0068] 16: Optical power balance control module

[0069] 17: Polarization adjustment and optimization control module

[0070] 18: Photoelectric processing module

[0071] 19: Central Control Module

[0072] 20: Data server DETAILED DESCRIPTION

[0073] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process. It should be noted that those skilled in the art may make various modifications and improvements without departing from the scope of the present invention, and these modifications and improvements fall within the scope of protection of the present invention.

[0074] Please see first Figure 1 , Figure 1 This is a schematic diagram of a measurement signal frame in an embodiment of the present invention. As shown in the figure, the structure of a measurement signal frame 1 is such that a complete measurement signal frame 1 covers the entire length of the optical fiber, with a duration of T0. Within each measurement signal frame 1, there are several measurement signal elements 2, which are arranged sequentially in the time domain, with varying time intervals between the internal pulse square waves. This time-division multiplexing approach effectively implements fully distributed optical fiber scanning measurements.

[0075] Figure 2 This is a schematic diagram of a measurement signal element according to an embodiment of the present invention. A measurement signal element 2 contains a high-power pump light 3 and a rectangular square wave probe light 4. The pump light and probe light are modulated by a specific time code, injected into the optical fiber with different delay times, and meet at a certain position in the optical fiber. These delay times are defined as τ i , is the relative time position of the pump light and the probe light in each measurement signal element 2 in the measurement signal frame 1, by adjusting the delay time τ i, their meeting at a specific location in the fiber can be precisely controlled. This time-coding method ensures that the pump and probe lights within measurement signal element 2 meet at the desired location. Stimulated Brillouin scattering occurs at this point, transferring energy from the pump light to the probe light, generating Brillouin scattered light. By collecting and analyzing this scattered light, the desired location can be measured.

[0076] In order to more clearly express the measurement process in the optical fiber, it is assumed that the duration of a measurement signal frame is T0, which is composed of m measurement signal elements τ0, that is:

[0077] T0=m*τ0

[0078] Where m is the number of measurement points in the optical fiber, which is related to the total length L0 of the optical fiber and the spatial resolution l0, that is:

[0079]

[0080] τ0 is the measurement signal element, which is related to the total length of the optical fiber L0 and the group velocity v g Relevant, namely:

[0081]

[0082] Where, the group velocity v g 2×10 8 m / s.

[0083] Here are two calculation examples: 1. In the long-distance demodulation example, assuming that the total length of the optical fiber L0 is 12 kilometers and the spatial resolution l0 is set to 0.01m, the number of measurement points m is 1.2×10 5 , the length of the measurement signal element τ0 is 120μs, and the length of the measurement signal frame T0 is 14.4s; 2. In the short-distance demodulation example, assuming that the length of the optical fiber L0 used for shape sensing on the intelligent robot arm is 20m, and the spatial resolution l0 is set to 0.002m, then the number of measurement points m is 1×10 4 , the length of the measurement signal element τ0 is 200ns, and the length of the measurement signal frame T0 is 2ms.

[0084] Furthermore, with the i-th measurement element τ i Complete the P in the optical fiber i The measurement at point τ0 is illustrated: The high-power pump pulse and the rectangular square wave probe light form a measurement signal element τ0, which occupies one measurement signal element in the time domain, such as 120 μs in the previous example. The two signals occupy two different frequencies in the frequency domain. The pump light frequency is assumed to be f0 or λ0. The probe light frequency is lower than the pump light frequency by the fiber Brillouin scattering Stokes frequency v. B , which can be expressed as f s=f0-v B From the time domain, the phase difference between the pump light and the probe light is τ i , the τ i The range is [0,τ0], and the specific size is related to the position of the measurement point. It is the detection light signal from the measured point forward to the end of the optical fiber, and then through the end FBG (the center frequency of FBG is the same as f s consistent) reflection, back to the measured point P i The time required. Assume that the time from fiber entry to the measured point P i The distance is L i , then τ i It can be expressed as:

[0085]

[0086] Specifically, the sequence of events from the probe light of the measurement signal element entering the fiber to the measured point, where the pump light and probe light generate Brillouin scattering signals, and then return to the fiber entrance can be briefly described as follows:

[0087] a) The detection light reaches the fiber entrance;

[0088] b) The probe light travels τ in the optical fiber i , the pump light reaches the fiber entrance and moves in the same direction;

[0089] c) The probe light and pump light travel in the same direction toward the measured point in the optical fiber;

[0090] d) The probe light and the pump light travel in the same direction until the probe light reaches the measured point P i ;

[0091] e) The probe light and pump light continue to travel until the probe light reaches the FBG at the end of the fiber and is reflected, completing the transmission process of the probe light along the entire length of the fiber, which takes τ0 / 2.

[0092] f) The probe light is reflected by the FBG and travels in the opposite direction to the pump light;

[0093] g) The probe light and the pump light meet at the measured point P i , and assuming that the power of the pump light is greater than the Brillouin threshold in the optical fiber, the generated Brillouin scattering gain energy is transferred to the probe light, forming a signal light carrying Brillouin scattering information;

[0094] h) The signal light carrying the Brillouin scattering information continues to travel in the reverse direction, and the pump light continues to move forward until it passes through

[0095] FBG, and leaves the sensing fiber;

[0096] i) The signal light carrying the Brillouin scattering information reaches the fiber entrance, completing a complete measurement process of the signal element.

[0097] In summary:

[0098] To more efficiently describe and implement optical fiber measurements, this invention introduces the concepts of "measurement signal frames" and "measurement signal elements." A measurement signal frame represents the scanning process of all points along the entire length of the fiber, while a measurement signal element represents the sensing unit measuring a single point. It internally defines the delay time between the pump and probe light at a specific measurement point on the fiber. By properly adjusting the measurement signal frame duration and the pulse square wave interval within each measurement signal element, each measurement point along the fiber can be accurately scanned.

[0099] In each measurement signal element, pump and probe light are injected into the optical fiber using a specific pulse coding scheme. A certain time delay exists between the pump and probe lights. Pulse coding allows precise control of the point at which the two lights intersect in the fiber, where energy transfer occurs. This energy transfer is based on stimulated Brillouin scattering. By detecting the frequency shift of the signal after energy transfer, changes in the external signal can be accurately detected.

[0100] Based on single-point measurement, this invention achieves sensing at multiple locations on the fiber by sequentially varying the time delay between pump and probe light. The pulsed square wave pairs in each measurement signal element transfer energy at different locations on the fiber, ultimately enabling full fiber scanning through a measurement signal frame composed of successive measurement signal elements.

[0101] Finally, the present invention allows for further optimization of measurement performance by adjusting both pulse width and amplitude. Pulse width adjustment directly impacts spatial resolution, while pulse amplitude influences signal strength and signal-to-noise ratio. Depending on the needs of different application scenarios, the present invention can achieve higher spatial resolution or maintain high measurement accuracy over a longer measurement range through flexible pulse modulation.

[0102] Figure 3 This is a schematic diagram of an embodiment of the present invention - an application of a distributed optical fiber sensing and transmission method based on optical packetization. Figure 3 As can be seen, each module is connected through a single-mode single-core optical fiber 5. The narrow linewidth wavelength tunable laser 13 generates high-quality continuous light that enters the 1*2 coupler 6 and is divided into two optical paths. One path is the pump light, which is modulated by the modulator 7 controlled by the ns pulse generator and the encoding module 14, and the other path is the probe light, which is modulated by the modulator 7 controlled by the 10GHz microwave source and the encoding module 15. The time delay τ between the pump light and the probe light is τ. iThe size is controlled by the central control module 19. The two optical paths are then amplified and polarized by the erbium-doped fiber amplifier 8 controlled by the optical power balance control module 16 and the polarization controller 9 controlled by the polarization adjustment and optimization control module 17. Finally, they are converged into one optical path by the 2*1 coupler 10, and injected into the single-mode single-core optical fiber 5 with a fiber Bragg grating 12 engraved on the end through the circulator 11 for measurement. The generated reverse propagating signal light is collected and processed by the optoelectronic processing module 18, and then enters the data server 20 through the central control module 19 for calculation and processing to obtain the size of the sensing quantity. Traverse all τ i , the complete scanning of the entire optical fiber can be achieved.

[0103] Below is Figure 3 More detailed explanation:

[0104] 1. Laser and optical signal generation module:

[0105] 1) Narrow linewidth wavelength tunable laser 13: This is the core light source of the system, responsible for providing stable, high-quality continuous light. Due to the narrow linewidth characteristics of the laser, it can generate a relatively pure single wavelength optical signal, avoiding the noise interference caused by the broadband light source. At the same time, after sideband modulation, it can generate detection light with a relatively accurate frequency deviation, which is crucial for subsequent Brillouin scattering measurements. This light source is Figure 1 The measurement signal frame 1 shown provides the basic optical signal.

[0106] 2) 1*2 coupler 6: Splits the continuous light output by the laser into two paths, one for generating pump light and the other for generating detection light. This branching allows the system to generate two optical signals with different functions at the same time. These two optical signals will be further modulated into Figure 2 The structure of the measurement signal element 2 is shown.

[0107] 2. Optical signal modulation and control module

[0108] 1) ns pulse generator and encoding module 14: The pump light is pulse modulated by the modulator 7, and its pulse width is controlled by the ns pulse generator and encoding module 14 to generate a high peak power pump pulse 3, so as to produce a more obvious energy transfer phenomenon in the subsequent interaction process. The modulated pump light will be further optimized by the erbium-doped fiber amplifier 8 and polarization controller 9. This module is responsible for generating Figure 2 The high-power pump pulse 3 shown in FIG. 1 is a key part of the measurement signal element 2 .

[0109] 2) 10GHz microwave source and encoding module 15: The detection light path is modulated by the 10GHz microwave source and encoding module 15 to form a rectangular square wave signal with a sideband of about 10GHz, i.e., the detection light signal. The modulation of the detection light is also controlled by the encoding module to ensure that its time delay relationship with the pump light is accurately controlled during measurement. This module is responsible for generating Figure 2 The rectangular square wave probe light 4 shown in the figure, together with the high power pump pulse 3, constitutes a complete measurement signal element 2.

[0110] 3) Central control module 19: This module is responsible for controlling the time delay between the pump light and the probe light. By adjusting the time interval between the two optical signals, it is possible to measure different points on the optical fiber. This dynamic delay control ensures Figure 1 The measurement signal frame 1 structure shown can be realized so that the system can complete a comprehensive scan of the entire optical fiber within one cycle T0.

[0111] 3. Optical signal amplification and optimization control

[0112] 1) Erbium-doped fiber amplifier 8: used to amplify the power of pump light and probe light to compensate for signal attenuation during long-distance fiber transmission.

[0113] The optical power balance control module 16 adjusts the gain of the amplifier in real time to ensure that the power of the pump light and the detection light in each measurement signal element 2 remains within a suitable range, thereby avoiding measurement errors caused by power imbalance.

[0114] 2) Polarization controller 9: used to adjust the polarization state of the optical signal. Because the scattering process in the optical fiber is easily affected by the polarization state of the optical signal, the polarization adjustment and optimization control module 17 can more accurately control the polarization state of the two signals in each measurement signal element 2 through the polarization controller 9 to maximize the signal quality.

[0115] 4. Optical signal combining and injection into optical fiber

[0116] 1) 2*1 coupler 10: re-converges the amplified and polarization-optimized pump light and probe light into one optical signal, forming a complete measurement signal element 2.

[0117] 2) Circulator 11: This device is a three-port passive optical device responsible for injecting the combined measurement signal element 2 into the single-mode single-core optical fiber 5, and can transmit the reverse propagating signal light to the optoelectronic processing module 18 for subsequent processing.

[0118] 5. Fiber Optic Sensing and Stimulated Brillouin Scattering

[0119] 1) Fiber Bragg Grating 12: A fiber Bragg grating 12 is inscribed at the end of the optical fiber. It reflects only the probe light, allowing all other signals to pass through. This allows the probe light and pump light to propagate in opposite directions, eventually meeting at a certain point in the fiber and causing stimulated Brillouin scattering. This ensures that the pump and probe lights in each measurement signal element 2 interact at the desired location to produce a scattered signal.

[0120] 2) Stimulated Brillouin Scattering: Stimulated Brillouin scattering is the detection mechanism of this system. It relies on the frequency shift of scattered light caused by changes in the optical properties of the fiber due to local strain or temperature changes. By accurately measuring the frequency shift of the scattered light, the strain or temperature change at the location of the stimulated Brillouin scattering in the fiber can be determined.

[0121] 6. Signal acquisition and processing

[0122] 1) Optoelectronic Processing Module 18: The reverse-propagating Brillouin scattered signal passes through circulator 11 and enters optoelectronic processing module 18. This module converts the optical signal into an electrical signal and performs a series of processing operations, including filtering, amplification, and demodulation. It processes the signal of each measurement signal element 2 sequentially, according to the structure of measurement signal frame 1.

[0123] 2) Data Server 20: The processed signal is transmitted to the data server 20 via the central control module 19. The server processes the signal using a pre-set algorithm to obtain sensor quantities such as strain or temperature at the measurement point. Each measurement signal element 2 within the measurement signal frame 1 is then mapped to a specific location on the optical fiber, enabling distributed parameter sensing across the entire optical fiber.

[0124] 7. Interconnection and collaboration of system modules

[0125] Central control module 19 collaborates with various functional modules: The central control module 19 not only controls core processes such as encoding, pulse delay, and signal acquisition and processing, but also interacts with the narrow-linewidth, wavelength-tunable laser 13, the nanosecond pulse generator and encoding module 14, the 10 GHz microwave source and encoding module 15, the optical power balance control module 16, the polarization adjustment and optimization control module 17, and the optoelectronic processing module 18 for digital signal exchange. Its core function is to coordinate the operations of these modules, ensuring the accurate implementation of the structure of the measurement signal frame 1 and the measurement signal element 2, and optimizing the operation of the entire system.

[0126] In summary, the distributed optical fiber sensing and transmission method based on optical grouping proposed in the present invention avoids the pumping light exhaustion effect and non-local effect, and improves the measurement accuracy; by adjusting the pulse parameters, the spatial resolution and measurement accuracy of the measuring point can be flexibly controlled. Under the premise of ensuring the resolution, the measurement of all points on the optical fiber is completed at one time, taking into account both resolution and time efficiency; the single-ended injection method is adopted, which not only reduces the hardware cost of arranging the light source at the other end of the optical fiber, but also makes the system more adaptable, especially in scenarios where the optical fiber end is difficult to access or the environment is complex; in addition, the present invention is not only applicable to the single-core optical fiber mentioned in the article, but also to multi-core optical fibers, providing a basis for vector sensing.

[0127] The above describes the specific embodiments of the present invention. It should be noted that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which will not affect the essence of the present invention.

Claims

1. A distributed optical fiber sensing and transmission method based on optical packetization, characterized in that: All-fiber scanning measurement is achieved using measurement signal frames, where each measurement signal frame contains a number of measurement signal elements, each of which is used to sense a predetermined measurement point in the optical fiber. The measurement signal elements include a pump light and a probe light, with a specific time delay relationship between the pump light and the probe light, which is used to generate a nonlinear scattering effect at the predetermined measurement point in the optical fiber. The relationship between the duration T0 of the measurement signal frame and the duration τ0 of the measurement signal element is determined by the following formula: T0=m*τ0; Where m is the number of measurement points in the optical fiber; The number of measurement points m in the optical fiber, the total length L0 of the optical fiber, and the spatial resolution l0 satisfy the following relationship: The time delay τ between the pump light and the probe light i With the measured point P i Distance L i The following relationship is satisfied: Among them, L i From the fiber entrance to the measured point P i distance; v g is the group velocity of light.

2. The distributed optical fiber sensing and transmission method based on optical packetization according to claim 1, characterized in that: The pump light is a high-power, narrow-pulse-width pulse, and the detection light is a rectangular square wave signal.

3. The distributed optical fiber sensing and transmission method based on optical packetization according to claim 2, characterized in that: The pump light and the probe light are injected into the optical fiber in the same direction but not at the same time. The probe light is reflected by the fiber Bragg grating (FBG) at the end of the optical fiber and becomes the reverse probe light. It propagates in the opposite direction to the pump light and meets the predetermined measurement point in the optical fiber to generate nonlinear scattering, including Brillouin scattering or Raman scattering.

4. The distributed optical fiber sensing and transmission method based on optical packetization according to claim 3, characterized in that: The time delay intervals between the pump light pulse and the detection light signal within each measurement signal element are different, so the constructed measurement signal frame can cover all measurement points on the optical fiber, realizing full-fiber distributed measurement.

5. The distributed optical fiber sensing and transmission method based on optical packetization according to claim 1, characterized in that: The time length τ0 of the measurement signal element is related to the total length L0 of the optical fiber and the group velocity v g The following relationship is satisfied:

6. The distributed optical fiber sensing and transmission method based on optical packetization according to claim 1, characterized in that: The following steps are involved: Generate stable, high-quality continuous light and divide it into pump light path and detection light path; Modulating the pump light and the probe light to generate a measurement signal element including a high-power pump pulse and a rectangular square wave probe light; Control the time delay between pump light and probe light; Power amplification and polarization optimization of pump light and probe light; Combine the pump light and the detection light and inject them into a single-mode single-core optical fiber; At the fiber Bragg grating at the end of the optical fiber, the probe light is reflected and propagates in opposite directions with the pump light. They meet at a predetermined position in the optical fiber and produce stimulated Brillouin scattering (SBS) effect. The signal acquisition and processing module is used to collect and process the reverse propagating Brillouin scattering signal to obtain the sensing quantity of the measurement point in the optical fiber.

7. A distributed optical fiber sensing and transmission system based on optical packetization, used to implement the distributed optical fiber sensing and transmission method based on optical packetization according to claim 1, characterized in that: include: Laser and optical signal generation module, used to generate stable, high-quality continuous light and divide it into pump light path and detection light path; An optical signal modulation and control module, which is used to modulate the pump light and probe light to generate a measurement signal element containing a high-power pump pulse and a rectangular square wave probe light; it includes a nanosecond pulse generator and encoding module for pulse modulation of the pump light, and a 10 GHz microwave source and encoding module for modulating the probe light; A central control module is used to control the time delay between the pump light and the probe light so that they meet at a predetermined position in the optical fiber and generate a stimulated Brillouin scattering effect; The optical signal amplification and optimization control module includes an erbium-doped fiber amplifier and a polarization controller, which is used to amplify the power and optimize the polarization of the pump light and the probe light; Optical signal combining and injection fiber module, including a 2*1 coupler and a circulator, used to combine pump light and detection light and inject them into a single-mode single-core fiber; Fiber sensing and stimulated Brillouin scattering module, including a fiber Bragg grating at the end of the optical fiber, used to reflect the probe light and make it propagate in the opposite direction of the pump light; The signal acquisition and processing module, including the optoelectronic processing module and the data server, is used to collect the reverse-propagating Brillouin scattering signal and process it to obtain the sensing quantity of the measurement point in the optical fiber; The measurement signal elements are arranged sequentially in the time domain to form a measurement signal frame covering the entire length of the optical fiber. By adjusting the time delay between the pump light and the probe light, their encounter at a certain position in the optical fiber can be controlled.

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