Weak fiber grating array sensing system and self-adaptive gain adjusting method and device thereof

Abstract

The invention discloses a self-adaptive gain adjustment method of a weak fiber grating array sensing system. The method comprises the following steps: step 20, setting the gain value of each weak fiber grating as the same initial value; step 30, determining a bias current corresponding to each weak fiber grating according to the gain value corresponding to each weak fiber grating; 40, sequentially outputting the bias current corresponding to each weak fiber grating to an SOA high-speed photoelectric switch, so that the SOA high-speed photoelectric switch performs gain amplification on the reflected light signal of each weak fiber grating by adopting the corresponding bias current; step 50, obtaining the reflected light signal of each weak fiber bragg grating after gain amplification so as to determine the intensity of the reflected signal of each weak fiber bragg grating after gain amplification; step 60, adjusting the gain value of each weak fiber bragg grating to a corresponding correction value according to the intensity of the reflected signal of each weak fiber bragg grating after gain amplification; and step 70, repeating the steps 30-60 by adopting the adjusted gain value so as to complete the next scanning period. The invention further discloses a gain adjusting method and a weak fiber grating array sensing system based on the self-adaptive gain adjusting method.

Description

Technical Field

[0001] The present invention relates to fiber grating sensing technology, and in particular to a weak fiber grating array sensing system and an adaptive gain adjustment method and device thereof. Background Art

[0002] Fiber Bragg grating (FBG) sensors are widely used in aerospace, deep-sea sensing, ecological monitoring, medical diagnosis, and other fields due to their small size, light weight, immunity to electromagnetic interference, intrinsic safety, and ease of forming sensor networks. Fiber Bragg grating arrays (FBGs) are a technology that connects multiple FBGs in series on a single optical fiber to achieve distributed fiber-optic sensing.

[0003] Ordinary fiber Bragg gratings (FBGs) have a high reflectivity, and optical signals attenuate rapidly after being reflected by multiple FBGs during transmission. Therefore, the number of FBGs connected in series on a single optical fiber generally cannot exceed several dozen, which greatly limits the fiber sensing distance. However, by using weak FBGs with low reflectivity (e.g., 0.1% reflectivity) and time-division multiplexing technology, hundreds of weak FBGs can be connected in series on a single optical fiber. If extremely weak FBGs (e.g., 0.01% reflectivity) are used, even thousands or even tens of thousands of them can be connected in series on a single optical fiber, significantly increasing the fiber sensing distance.

[0004] For example, Chinese patent application number CN201210391578.5 discloses an extremely weak fiber Bragg grating sensing system and its query method, which uses two SOA high-speed photoelectric switches to implement the modulation module and sampling module of the extremely weak fiber Bragg grating sensing system. The first SOA high-speed photoelectric switch in the modulation module is used to modulate and gain amplify the light source signal input into the extremely weak fiber Bragg grating array, and the second SOA high-speed photoelectric switch in the sampling module is used to separate and gain amplify the reflected light pulses output by the extremely weak fiber Bragg grating array.

[0005] However, the gain value used by the SOA high-speed photoelectric switch is fixed, and the system cannot provide feedback adjustment. Due to temperature fluctuations, fiber aging, increased insertion loss, and other factors, the reflected signal intensity of each extremely weak fiber Bragg grating (FBG) output will vary. Therefore, frequent manual adjustment of the gain value of the second SOA high-speed photoelectric switch is required, making system maintenance more cumbersome. Furthermore, the reflected signal intensity of each extremely weak fiber Bragg grating varies, with some being strong and some being weak. As the number of gratings increases, the reflected signal intensity of the extremely weak fiber Bragg gratings closer to the end of the fiber decreases, while the reflected signal intensity of the extremely weak fiber Bragg gratings closer to the beginning of the fiber increases. The fixed gain value used by the second SOA high-speed photoelectric switch clearly cannot balance weak signal detection sensitivity with strong signal gain amplification saturation, which seriously affects demodulation accuracy and system stability. Summary of the Invention

[0006] In order to solve the above-mentioned deficiencies in the prior art, the present invention provides a weak fiber Bragg grating array sensing system and an adaptive gain adjustment method and device thereof, which can feedback adjust the gain value of the SOA high-speed photoelectric switch.

[0007] The technical problem to be solved by the present invention is achieved through the following technical solutions: An adaptive gain adjustment method for a weak fiber grating array sensing system comprises the following steps: Step 20: setting the gain values of each weak fiber Bragg grating to the same initial value; Step 30: Determine the bias current corresponding to each weak fiber Bragg grating according to the gain value corresponding to each weak fiber Bragg grating; Step 40: sequentially outputting bias currents corresponding to the respective weak fiber Bragg gratings to the SOA high-speed photoelectric switch, so that the SOA high-speed photoelectric switch performs gain amplification on the reflected light signals of the respective weak fiber Bragg gratings using the corresponding bias currents; Step 50: Acquire the reflected light signals of each weak fiber Bragg grating after gain amplification to determine the reflected signal intensity of each weak fiber Bragg grating after gain amplification; Step 60: adjusting the gain value of each weak fiber Bragg grating to a corresponding correction value according to the reflection signal intensity of each weak fiber Bragg grating after gain amplification; Step 70: Repeat steps 30 to 60 using the adjusted gain value to complete the next scanning cycle.

[0008] Furthermore, the adaptive gain adjustment method further includes the following steps: Step 10: Set the initial value.

[0009] Furthermore, in step 60, when the gain value of each weak fiber Bragg grating is adjusted to a corresponding correction value according to the reflection signal intensity of each weak fiber Bragg grating after gain amplification, the following steps are included: Step 61: Subtracting the reflected signal intensity of each weak fiber Bragg grating after gain amplification from the set intensity threshold value to calculate the intensity error value of each weak fiber Bragg grating; Step 62: Compare the intensity error values of each weak fiber Bragg grating with the set error threshold, and adjust the gain value of each weak fiber Bragg grating to a corresponding correction value according to the comparison result to form an adjusted gain value.

[0010] Furthermore, the adaptive gain adjustment method further includes the following steps: Step 10: Set the intensity threshold and error threshold.

[0011] Furthermore, in step 62, if the absolute value of the intensity error value of a certain weak fiber Bragg grating is less than the set error threshold, the gain value of the weak fiber Bragg grating is maintained unchanged; if the intensity error value of a certain weak fiber Bragg grating is positive and its absolute value is greater than the set error threshold, the gain value of the weak fiber Bragg grating is reduced; if the intensity error value of a certain weak fiber Bragg grating is negative and its absolute value is greater than the set error threshold, the gain value of the weak fiber Bragg grating is increased.

[0012] A gain adjustment device for a weak fiber Bragg grating array sensing system, used in the above-mentioned adaptive gain adjustment method; the gain adjustment device comprises a power supply module, a data processing module and a constant current source module, the data processing module and the constant current source module are connected, and the power supply module is respectively connected to the data processing module and the constant current source module; The data processing module is used to obtain the reflected light signal of each weak fiber Bragg grating after gain amplification to determine the intensity of the reflected signal of each weak fiber Bragg grating after gain amplification, and then adjust the gain value of each weak fiber Bragg grating to a corresponding correction value according to the intensity of the reflected signal of each weak fiber Bragg grating after gain amplification, and in the next scanning cycle, use the adjusted gain value to re-determine the bias current corresponding to each weak fiber Bragg grating; The constant current source module is used to sequentially output the bias current corresponding to each weak fiber Bragg grating to the SOA high-speed photoelectric switch, so that the SOA high-speed photoelectric switch uses the corresponding bias current to perform gain amplification on the reflected light signal of each weak fiber Bragg grating; The power supply module is used to provide operating current for the data processing module and the constant current source module.

[0013] Furthermore, a digital-to-analog conversion module is connected between the data processing module and the constant current source module, and the digital-to-analog conversion module is used to convert the digital signal output by the data processing module into an analog voltage of the constant current source module.

[0014] Furthermore, the constant current source module is connected to the data processing module through a level conversion module to perform level conversion on the digital signal output by the data processing module; the power supply module is also connected to the level conversion module to provide a reference voltage to the level conversion module.

[0015] Furthermore, the data processing module is an FPGA module.

[0016] A weak fiber Bragg grating array sensing system comprises a broadband light source, a first SOA high-speed photoelectric switch, an erbium-doped fiber amplifier, a fiber circulator, a weak fiber Bragg grating array, a second SOA high-speed photoelectric switch, a photodetector, an analog-to-digital converter, a signal generator, the aforementioned gain adjustment device, and a host computer. The weak fiber Bragg grating array comprises a sensing fiber and a plurality of weak fiber Bragg gratings, each of which is sequentially connected in series along the axial direction of the sensing fiber. The output end of the broadband light source is sequentially connected to the first end of the fiber circulator through the first SOA high-speed photoelectric switch and the erbium-doped fiber amplifier, the head end of the weak fiber Bragg grating array is connected to the second end of the fiber circulator, and the input end of the photodetector is connected to the third end of the fiber circulator through the second SOA high-speed photoelectric switch. The output end of the photodetector is sequentially connected to the input end of the host computer through the analog-to-digital converter and the gain adjustment device. The two output ends of the signal generator are respectively connected to the pump current ends of the first and second SOA high-speed photoelectric switches. The output end of the gain adjustment device is connected to the bias current end of the second SOA high-speed photoelectric switch.

[0017] The present invention has the following beneficial effects: the weak fiber Bragg grating array sensing system and its adaptive gain adjustment method and device of the present invention perform feedback adjustment on the gain value used by the SOA high-speed photoelectric switch in the next scanning cycle according to the reflection signal intensity of each weak fiber Bragg grating after gain amplification by the SOA high-speed photoelectric switch in the previous scanning cycle, thereby realizing adaptive gain control of the SOA high-speed photoelectric switch, eliminating the need for manual adjustment of the gain value to cope with the influences of temperature fluctuations, fiber aging, increased insertion loss, etc., and each weak fiber Bragg grating adopts a corresponding gain value for gain amplification, which can take into account both the weak signal detection sensitivity and the strong signal gain amplification saturation problem. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a structural principle diagram of the weak fiber grating array sensing system provided by the present invention.

[0019] Figure 2 This is a schematic diagram of the steps of the adaptive gain adjustment method provided by the present invention.

[0020] Figure 3 This is a structural principle diagram of the gain adjustment device provided by the present invention. DETAILED DESCRIPTION

[0021] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0022] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0023] Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first," "second," or "third" may explicitly or implicitly include one or more of such features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0024] In the present invention, unless otherwise expressly specified or limited, terms such as "installed," "connected," "connect," "fixed," and "disposed" should be understood in a broad sense. For example, they may refer to fixed or detachable connections, or integration; mechanical or electrical connections; direct or indirect connections through an intermediate medium; or internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0025] Example 1 like Figure 1As shown, a weak fiber Bragg grating array sensing system includes a broadband light source 1, a first SOA high-speed photoelectric switch 2, an erbium-doped fiber amplifier 3, a fiber circulator 4, a weak fiber Bragg grating array 5, a second SOA high-speed photoelectric switch 6, a photodetector 7, an analog-to-digital converter 8, a signal generator 9, a gain adjustment device 10 and a host computer 11. The weak fiber Bragg grating 41 array 3 includes a sensing fiber and a plurality of weak fiber Bragg gratings 41, and each weak fiber Bragg grating 41 is sequentially connected in series along the axial direction of the sensing fiber; the output end of the broadband light source 1 is connected to the first SOA high-speed photoelectric switch 2 and the erbium-doped fiber amplifier 3 of the fiber circulator 4 in sequence. One end, the head end of the weak fiber Bragg grating 41 array 3 is connected to the second end of the fiber circulator 4, and the input end of the photodetector 7 is connected to the third end of the fiber circulator 4 through the second SOA high-speed photoelectric switch 6; the output end of the photodetector 7 is connected to the input end of the host computer 11 through the analog-to-digital converter 8 and the gain adjustment device 10 in sequence; the two output ends of the signal generator 9 are respectively connected to the pump current ends of the first SOA high-speed photoelectric switch 2 and the second SOA high-speed photoelectric switch 6; the output end of the gain adjustment device 10 is connected to the bias current end of the second SOA high-speed photoelectric switch 6.

[0026] During sensing, the signal generator 9 generates two electrical pulse signals, which are respectively output to the first SOA high-speed photoelectric switch 2 and the second SOA high-speed photoelectric switch 6 to control the first SOA high-speed photoelectric switch 2 and the second SOA high-speed photoelectric switch 6 to realize regular on-off. The continuous optical signal emitted by the broadband light source 1 is modulated by the first SOA high-speed photoelectric switch 2 and gain-amplified to form an optical pulse signal. The optical pulse signal is gain-amplified by the erbium-doped fiber amplifier 3 and input into the weak fiber Bragg grating 41 array 3 through the optical fiber circulator 4. Each weak fiber Bragg grating 41 reflects the optical pulse. The reflected light signal formed by the signal is output to the second SOA high-speed photoelectric switch 6 through the optical fiber circulator 4, and is separated and gain-amplified by the second SOA high-speed photoelectric switch 6 before being output to the photodetector 7 for collection. The reflected light signal collected by the photodetector 7 is converted into a digital signal by the analog-to-digital converter 8 and then provided to the gain adjustment device 10 for processing. The gain adjustment device 10 performs feedback adjustment on the gain value of the second SOA high-speed photoelectric switch 6 based on the reflected light signals of each weak optical fiber Bragg grating 41, and provides the final reflected light signal to the host computer 11 for sensing, demodulation, and display.

[0027] The signal generator 9 may be connected to the host computer 11 and directly controlled by the host computer 11 , or may be connected to the gain adjustment device 10 and indirectly controlled by the host computer 11 through the gain adjustment device 10 .

[0028] In this patent, the weak fiber Bragg grating 41 refers to a fiber Bragg grating with a reflectivity of 0.1% or less, including an extremely weak fiber Bragg grating with a reflectivity of 0.01% and even a fiber Bragg grating with a lower reflectivity.

[0029] In a specific implementation, if the power of the broadband light source 1 is sufficiently high, the first SOA high-speed photoelectric switch 2 does not need to perform gain amplification on the continuous optical signal emitted by the broadband light source 1, and only needs to modulate the continuous optical signal to form the optical pulse signal. If the power of the broadband light source 1 is relatively low, the first SOA high-speed photoelectric switch 2 can use a fixed gain value, such as the maximum gain value, to perform gain amplification on the continuous optical signal while modulating the continuous optical signal emitted by the broadband light source 1. Of course, the output end of the gain adjustment device 10 can also be connected to the bias current terminal of the first SOA high-speed photoelectric switch 2 to provide feedback adjustment on the gain value of the first SOA high-speed photoelectric switch 2.

[0030] In this embodiment, the gain adjustment device 10 is only used to perform feedback adjustment on the gain value of the second SOA high-speed photoelectric switch 6 , and does not need to perform feedback adjustment on the gain value of the first SOA high-speed photoelectric switch 2 .

[0031] Example 2 like Figure 2 As shown, an adaptive gain adjustment method is used in the weak fiber Bragg grating array sensing system described in Example 1, so that the gain adjustment device performs feedback adjustment on the gain value of the second SOA high-speed photoelectric switch.

[0032] The adaptive gain adjustment method includes at least two scanning cycles, and the steps are as follows: Step 10: Set the initial value, intensity threshold, and error threshold.

[0033] In step 10, the technician sets the initial value, intensity threshold, and error threshold for the gain adjustment device through the host computer. There is only one initial value, intensity threshold, and error threshold, and all weak fiber Bragg gratings use the same initial value, intensity threshold, and error threshold. The gain adjustment device adjusts the gain value of each weak fiber Bragg grating from the same initial value to its corresponding correction value through the adaptive gain adjustment method of this patent.

[0034] Step 20: Set the gain values of each weak fiber Bragg grating to the same initial value.

[0035] In step 20, after the weak fiber Bragg grating array sensing system is turned on and initialized, the host computer sends the set initial value, intensity threshold and error threshold to the gain adjustment device. After receiving the initial value, intensity threshold and error threshold, the gain adjustment device first stores them locally, and in the first scanning cycle, first reads the locally stored initial value, and then sets the gain value of each weak fiber Bragg grating to the initial value.

[0036] Step 30: Determine the bias current corresponding to each weak fiber Bragg grating according to the gain value corresponding to each weak fiber Bragg grating.

[0037] In step 30, a lookup table or calculation formula between gain value and bias current is provided in the gain adjustment device, so as to determine the bias current corresponding to each weak fiber Bragg grating by looking up the table or calculating.

[0038] Step 40: sequentially outputting bias currents corresponding to the respective weak fiber Bragg gratings to the second SOA high-speed photoelectric switch, so that the second SOA high-speed photoelectric switch performs gain amplification on the reflected light signals of the respective weak fiber Bragg gratings using the corresponding bias currents.

[0039] In step 40, each weak fiber Bragg grating (FBG) is positioned at different distances within the weak fiber Bragg grating array. Therefore, the reflected light signals generated by each weak fiber Bragg grating have different time delays (i.e., the time interval between the output of the pulsed light signal by the first SOA high-speed photoelectric switch and the input of the reflected light signal by the second SOA high-speed photoelectric switch). The gain adjustment device can determine the weak fiber Bragg grating (FBG) corresponding to each reflected light signal based on the time delays of the different reflected light signals, and thereby sequentially output corresponding bias currents to the second SOA high-speed photoelectric switches, so that the second SOA high-speed photoelectric switches can perform gain amplification on each reflected light signal using the corresponding bias current.

[0040] Step 50: Acquire the reflected light signal of each weak fiber Bragg grating after gain amplification to determine the intensity of the reflected signal of each weak fiber Bragg grating after gain amplification.

[0041] In step 50, the reflected light signals of each weak fiber Bragg grating collected by the photoelectric detector after gain amplification are converted into digital signals by the analog-to-digital converter and then output to the gain adjustment device. The gain adjustment device can determine the intensity of the reflected signal of each weak fiber Bragg grating after gain amplification based on the signal size output by the analog-to-digital converter.

[0042] Step 60: According to the reflection signal intensity of each weak fiber Bragg grating after gain amplification, the gain value of each weak fiber Bragg grating is adjusted to a corresponding correction value.

[0043] In step 60, when the reflected light signal of a weak fiber Bragg grating is gain-amplified by the second SOA high-speed photoelectric switch and its reflected signal intensity is too large, the gain adjustment device adjusts the gain value corresponding to the weak fiber Bragg grating to decrease; when the reflected light signal of a weak fiber Bragg grating is gain-amplified by the second SOA high-speed photoelectric switch and its reflected signal intensity is too small, the gain adjustment device adjusts the gain value corresponding to the weak fiber Bragg grating to increase.

[0044] The gain value corresponding to each weak fiber Bragg grating can be adjusted in a step-by-step manner, that is, when the gain value corresponding to each weak fiber Bragg grating is increased or decreased, the gain variable increased or decreased each time is fixed.

[0045] After adjusting the gain value of each weak fiber Bragg grating to the corresponding correction value, the gain adjustment device first stores the adjusted gain value locally for reading in the next scanning cycle.

[0046] Specifically, in step 60, when adjusting the gain value of each weak fiber Bragg grating to a corresponding correction value according to the reflection signal intensity of each weak fiber Bragg grating after gain amplification, the following steps are included: Step 61: Subtract the reflected signal intensity of each weak fiber Bragg grating after gain amplification from the set intensity threshold value to calculate the intensity error value of each weak fiber Bragg grating.

[0047] In step 61, the intensity error value has a numerical attribute and a positive and negative attribute. The numerical attribute represents the degree of deviation between the reflected signal intensity of each weak fiber Bragg grating and the target signal intensity. The positive and negative attribute represents the direction of deviation between the reflected signal intensity of each weak fiber Bragg grating and the target signal intensity.

[0048] Step 62: Compare the intensity error values of each weak fiber Bragg grating with the set error threshold respectively, and adjust the gain value of each weak fiber Bragg grating to a corresponding correction value according to the comparison result to form an adjusted gain value.

[0049] In step 62, if the absolute value of the intensity error value of a certain weak fiber Bragg grating is less than the set error threshold, the gain value of the weak fiber Bragg grating is maintained unchanged; if the intensity error value of a certain weak fiber Bragg grating is positive and its absolute value is greater than the set error threshold, the gain value of the weak fiber Bragg grating is reduced; if the intensity error value of a certain weak fiber Bragg grating is negative and its absolute value is greater than the set error threshold, the gain value of the weak fiber Bragg grating is increased.

[0050] Preferably, the absolute value of the intensity error value of each weak fiber Bragg grating is first taken, and then the absolute value of each intensity error value is compared with the set error threshold. If the absolute value of a certain intensity error value is less than the set error threshold, the gain value of the weak fiber Bragg grating is maintained unchanged and stored locally; if the absolute value of a certain intensity error value is greater than the set error threshold, the positive or negative sign of the intensity error value is further judged. If the intensity error value is positive, the gain value of the weak fiber Bragg grating is reduced and stored locally. If the intensity error value is negative, the gain value of the weak fiber Bragg grating is increased and stored locally.

[0051] Step 70: Repeat steps 30 to 60 using the adjusted gain value to complete the next scanning cycle.

[0052] In step 70, the gain adjustment device redetermines the bias current corresponding to each weak fiber Bragg grating according to the adjusted gain value in the next scanning cycle, and then outputs the redetermined bias current corresponding to each weak fiber Bragg grating to the second SOA high-speed photoelectric switch in sequence, and continuously repeats steps 30 to 60 until the reflected signal intensity of each weak fiber Bragg grating after gain amplification is within an appropriate range.

[0053] Example 3 like Figure 3 As shown, a gain adjustment device is used in the weak fiber grating array sensing system described in the first embodiment to implement the adaptive gain adjustment method described in the second embodiment.

[0054] The gain adjustment device includes a power supply module, a data processing module and a constant current source module, the data processing module and the constant current source module are connected, and the power supply module is connected to the data processing module and the constant current source module respectively; The data processing module is used to obtain the reflected light signal of each weak fiber Bragg grating after gain amplification to determine the intensity of the reflected signal of each weak fiber Bragg grating after gain amplification, and then adjust the gain value of each weak fiber Bragg grating to a corresponding correction value according to the intensity of the reflected signal of each weak fiber Bragg grating after gain amplification, and in the next scanning cycle, use the adjusted gain value to re-determine the bias current corresponding to each weak fiber Bragg grating; The constant current source module is used to sequentially output the bias current corresponding to each weak fiber Bragg grating to the second SOA high-speed photoelectric switch, so that the second SOA high-speed photoelectric switch uses the corresponding bias current to perform gain amplification on the reflected light signal of each weak fiber Bragg grating; The power supply module is used to provide operating current for the data processing module and the constant current source module.

[0055] Preferably, a digital-to-analog conversion module is connected between the data processing module and the constant current source module, and the digital-to-analog conversion module is used to convert the digital signal output by the data processing module into an analog voltage of the constant current source module.

[0056] Preferably, the constant current source module is connected to the data processing module through a level conversion module to perform level conversion on the digital signal output by the data processing module; the power supply module is also connected to the level conversion module to provide a reference voltage to the level conversion module.

[0057] In this embodiment, the data processing module is an FPGA module.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention rather than to limit them. Although the embodiments of the present invention are described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the embodiments of the present invention can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An adaptive gain adjustment method for a weak fiber Bragg grating array sensing system, characterized in that: The steps include: Step 20: setting the gain values of each weak fiber Bragg grating to the same initial value; Step 30: Determine the bias current corresponding to each weak fiber Bragg grating according to the gain value corresponding to each weak fiber Bragg grating; Step 40: sequentially outputting bias currents corresponding to the respective weak fiber Bragg gratings to the SOA high-speed photoelectric switch, so that the SOA high-speed photoelectric switch performs gain amplification on the reflected light signals of the respective weak fiber Bragg gratings using the corresponding bias currents; Step 50: Acquire the reflected light signals of each weak fiber Bragg grating after gain amplification to determine the reflected signal intensity of each weak fiber Bragg grating after gain amplification; Step 60: adjusting the gain value of each weak fiber Bragg grating to a corresponding correction value according to the reflection signal intensity of each weak fiber Bragg grating after gain amplification; Step 70: Repeat steps 30 to 60 using the adjusted gain value to complete the next scanning cycle.

2. The adaptive gain adjustment method according to claim 1, wherein: The adaptive gain adjustment method further comprises the following steps: Step 10: Set the initial value.

3. The adaptive gain adjustment method according to claim 1, wherein: In step 60, when adjusting the gain value of each weak fiber Bragg grating to a corresponding correction value according to the reflected signal intensity of each weak fiber Bragg grating after gain amplification, the following steps are included: Step 61: Subtracting the reflected signal intensity of each weak fiber Bragg grating after gain amplification from the set intensity threshold value to calculate the intensity error value of each weak fiber Bragg grating; Step 62: Compare the intensity error values of each weak fiber Bragg grating with the set error threshold, and adjust the gain value of each weak fiber Bragg grating to a corresponding correction value according to the comparison result to form an adjusted gain value.

4. The adaptive gain adjustment method according to claim 3, wherein: The adaptive gain adjustment method further comprises the following steps: Step 10: Set the intensity threshold and error threshold.

5. The adaptive gain adjustment method according to claim 3, wherein: In step 62, if the absolute value of the intensity error value of a certain weak fiber Bragg grating is less than the set error threshold, the gain value of the weak fiber Bragg grating is maintained unchanged; if the intensity error value of a certain weak fiber Bragg grating is positive and its absolute value is greater than the set error threshold, the gain value of the weak fiber Bragg grating is reduced; if the intensity error value of a certain weak fiber Bragg grating is negative and its absolute value is greater than the set error threshold, the gain value of the weak fiber Bragg grating is increased.

6. A gain adjustment device for a weak fiber Bragg grating array sensing system, characterized in that: Used to implement the adaptive gain adjustment method according to claim 1; the gain adjustment device includes a power supply module, a data processing module and a constant current source module, the data processing module and the constant current source module are connected, and the power supply module is connected to the data processing module and the constant current source module respectively; The data processing module is used to obtain the reflected light signal of each weak fiber Bragg grating after gain amplification to determine the intensity of the reflected signal of each weak fiber Bragg grating after gain amplification, and then adjust the gain value of each weak fiber Bragg grating to a corresponding correction value according to the intensity of the reflected signal of each weak fiber Bragg grating after gain amplification, and in the next scanning cycle, use the adjusted gain value to re-determine the bias current corresponding to each weak fiber Bragg grating; The constant current source module is used to sequentially output the bias current corresponding to each weak fiber Bragg grating to the SOA high-speed photoelectric switch, so that the SOA high-speed photoelectric switch uses the corresponding bias current to perform gain amplification on the reflected light signal of each weak fiber Bragg grating; The power supply module is used to provide operating current for the data processing module and the constant current source module.

7. The gain adjustment device according to claim 6, characterized in that: A digital-to-analog conversion module is connected between the data processing module and the constant current source module. The digital-to-analog conversion module is used to convert the digital signal output by the data processing module into an analog voltage of the constant current source module.

8. The gain adjustment device according to claim 6, wherein: The constant current source module is connected to the data processing module through a level conversion module to perform level conversion on the digital signal output by the data processing module; the power supply module is also connected to the level conversion module to provide a reference voltage to the level conversion module.

9. The gain adjustment device according to claim 6, wherein: The data processing module is an FPGA module.

10. A weak fiber Bragg grating array sensing system, characterized in that: The invention comprises a broadband light source, a first SOA high-speed photoelectric switch, an erbium-doped fiber amplifier, a fiber circulator, a weak fiber Bragg grating array, a second SOA high-speed photoelectric switch, a photodetector, an analog-to-digital converter, a signal generator, the gain adjustment device according to claim 6, and a host computer, wherein the weak fiber Bragg grating array comprises a sensing fiber and a plurality of weak fiber Bragg gratings, and each weak fiber Bragg grating is sequentially connected in series along the axial direction of the sensing fiber; the output end of the broadband light source is sequentially connected to the first end of the fiber circulator through the first SOA high-speed photoelectric switch and the erbium-doped fiber amplifier, the head end of the weak fiber Bragg grating array is connected to the second end of the fiber circulator, the input end of the photodetector is connected to the third end of the fiber circulator through the second SOA high-speed photoelectric switch; the output end of the photodetector is sequentially connected to the input end of the host computer through the analog-to-digital converter and the gain adjustment device; the two output ends of the signal generator are respectively connected to the pump current ends of the first SOA high-speed photoelectric switch and the second SOA high-speed photoelectric switch; and the output end of the gain adjustment device is connected to the bias current end of the second SOA high-speed photoelectric switch.

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