A fiber grating sensing system based on swept laser

Abstract

The present invention discloses a fiber Bragg grating sensing system based on a frequency sweeping laser in the field of fiber Bragg grating sensing technology, aiming to solve the problem that the fiber Bragg grating sensing system in the prior art cannot demodulate high-speed dynamic signals and needs to improve the demodulation speed in the face of large-scale projects. It includes an FPGA main control board, which is used to control the operation and stop of the entire sensing system; the frequency sweeping laser is used to output laser light, which is transmitted to the demodulation module unit through the reference optical path unit and the fiber Bragg grating array unit respectively; the demodulation module unit is used to transmit the sensing signals of the reference optical path unit and the fiber Bragg grating array unit to the upper computer software system after demodulation and processing; the present invention is suitable for fiber Bragg grating sensing work, and the frequency sweeping laser is provided by the frequency sweeping laser, which can not only act as a light source to reduce the cost of the fiber Bragg grating sensing system, but also can be applied to the demodulation technology to further improve the demodulation speed, and can be suitable for the rapid acquisition and processing of massive data information.

Description

Technical Field

[0001] The invention relates to a fiber grating sensing system based on a frequency sweeping laser, belonging to the technical field of fiber grating sensing. Background Art

[0002] Based on the sensing structure of fiber grating, the changes at the measured point can be directly or indirectly obtained by demodulating the spectral information of the reflected light. Using traditional broadband light sources and spectrometers to build a fiber optic sensing system can achieve a data demodulation capability of several kHz. When faced with some large-scale infrastructure or the entire factory machinery equipment to demodulate data from hundreds of measurement points, the traditional construction method is no longer applicable, and the sensitivity will be greatly reduced. In addition, the spectrometer or other traditional demodulation equipment is too large, which will add a lot of trouble in actual engineering applications.

[0003] There are many demodulation methods for fiber Bragg grating sensor systems, but they all have many disadvantages. For example, the spectrometer detection method can directly obtain the spectrum of the signal and then obtain the data of each parameter, but due to its large size and high price, it is only suitable for laboratory researchers to use; the matched filter method can demodulate the reflected light signal through a reference grating, but its demodulation range is too small, often only a few nm; the tunable Fabry-Perot filtering method uses a Fabry-Perot filter. When its transmission wavelength matches the central wavelength of the fiber Bragg grating reflected light, the photodetector can receive the strongest light intensity and then demodulate the central wavelength of the reflected light signal, but it is only suitable for the demodulation of static signals.

[0004] The existing fiber Bragg grating sensing system cannot demodulate high-speed dynamic signals. In the face of large-scale projects, the demodulation speed needs to be improved. In addition, the existing system is too large and has a low degree of integration. In order to achieve rapid collection and accurate monitoring of multi-point data, it is necessary to design a light source that can provide sufficient signal strength, bandwidth and faster light output speed and a device that can quickly demodulate the central wavelength of the fiber Bragg grating to improve the overall data acquisition capability of the fiber Bragg grating sensing system, while promoting the development of demodulation equipment towards integration and miniaturization. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a fiber Bragg grating sensing system based on a swept frequency laser to solve the problem that the existing fiber Bragg grating sensing system cannot demodulate high-speed dynamic signals and needs to improve the demodulation speed in the face of large-scale projects.

[0006] In order to solve the above technical problems, the present invention is implemented by adopting the following technical solutions:

[0007] The present invention provides a fiber grating sensing system based on a frequency sweeping laser, comprising an FPGA main control board, a frequency sweeping laser, a reference optical path unit, a fiber grating array unit, a demodulation module unit and a host computer software system;

[0008] The FPGA main control board is used to control the operation and stop of the entire sensor system;

[0009] The frequency sweeping laser is connected to the reference optical path unit and the fiber grating array unit, and outputs tunable laser light in the running state, which is transmitted to the demodulation module unit through the reference optical path unit and the fiber grating array unit respectively;

[0010] The demodulation module unit is used to demodulate the sensing signals of the reference optical path unit and the fiber grating array unit and transmit them to the host computer software system to realize sensing and monitoring of the environment.

[0011] Furthermore, the frequency sweeping laser includes a Fabry-Perot filter, a first fiber coupler, a semiconductor optical amplifier, a second fiber coupler, a filter control circuit and a semiconductor optical amplifier driving circuit. The Fabry-Perot filter, the first fiber coupler and the semiconductor optical amplifier are connected in sequence through a single-mode optical fiber to form a ring cavity. The second fiber coupler is used to split the output laser of the ring cavity so that it enters the reference optical path unit and the fiber grating array unit respectively. The filter control circuit is used to drive the Fabry-Perot filter and control the temperature of the Fabry-Perot filter. The semiconductor optical amplifier driving circuit is used to drive the semiconductor optical amplifier and control the temperature of the semiconductor optical amplifier. Optical isolators are installed at both ends of the semiconductor optical amplifier to realize unidirectional transmission of the laser in the cavity and avoid mode competition.

[0012] Furthermore, the physical length of the annular cavity is 25-27 cm.

[0013] Furthermore, the Fabry-Perot filter uses potassium sodium niobate piezoelectric ceramics and AL2O3 antireflection film; the piezoelectric coefficient of potassium sodium niobate piezoelectric ceramics is 330pC / N, the electromechanical coupling coefficient is 0.61, the Curie temperature is 220°C, the tuning speed of the FP cavity is less than 50ns, the insertion loss is 0.3db, the fineness is 5000, the bandwidth is 0.012nm, and the central wavelength peak transmittance is 99.7%;

[0014] The swept frequency laser can provide a swept frequency laser with a sweeping speed of 3 MHz, an output power of 50 mw, and a central wavelength in the range of 1230-1390 nm. The relationship between the central wavelength y of the output laser of the swept frequency laser and the driving voltage x of the Fabry-Perot filter is y=1236.83024+3.41476x.

[0015] Furthermore, the reference optical path unit includes an optical circulator and a fiber grating sensor connected to the optical circulator, the optical circulator includes one port, two ports and three ports, the one port is a frequency sweeping laser incident port, after the frequency sweeping laser is emitted through the two ports and enters the fiber grating sensor, its reflected light is emitted through the three ports to the demodulation module unit for demodulation.

[0016] Furthermore, the fiber grating array unit includes a plurality of optical circulators 2 and a multi-channel fiber grating sensor connected to the optical circulators 2; the optical circulators 2 include four ports, five ports and six ports; the four ports are frequency sweeping laser incident ports, and after the frequency sweeping laser is emitted through the five ports and enters the multi-channel fiber grating sensor, its reflected light is emitted through the six ports to the demodulation module unit for demodulation.

[0017] Furthermore, the demodulation module unit includes a photoelectric conversion module, a filtering and amplifying module, an A / D data sampling module and a serial communication module connected in sequence. The reflected light first enters the photoelectric conversion module to convert the optical signal into a voltage signal, and then is input into the filtering and amplifying module to shape and amplify the signal. The A / D data sampling module then converts the analog signal into a digital signal, and finally transmits the signal to the host computer software system through the serial communication module for processing.

[0018] Furthermore, the central wavelength of the fiber Bragg grating sensor is fixed, and a default value of the central wavelength demodulation data of the reference optical path unit is set in the host computer software system. When the demodulation data of the fiber Bragg grating sensor is inconsistent with the default value, error compensation is performed on the demodulation module unit.

[0019] Furthermore, the host computer software system is used to display the demodulated information in real time after data processing.

[0020] Furthermore, the photoelectric conversion module uses a PbSe avalanche photodiode, and the concentration of Si doping in the buffer layer, multiplication layer, and charge layer is 1.1×10 18 cm -3 , 0.35×10 16 cm -3 , 8×10 16 cm -3 The absorption layer is PbSe film, and the active area of ​​PbSe film is 0.5×0.5mm 2 , thickness is 36μm, module responsivity is 20A / W, conversion gain is 1×10 5 mV / mW, and the noise equivalent power is 1pW / √Hz.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The fiber Bragg grating sensing system based on frequency-sweep laser can provide frequency-sweep laser through frequency-sweep laser, which can not only act as a light source to further reduce the cost of the fiber Bragg grating sensing system, but also be applied to demodulation technology to further improve the demodulation speed, which can be suitable for the rapid acquisition and processing of massive data information;

[0023] 2. The present invention controls the frequency sweeping laser to reduce the influence of temperature drift by cooperating with the filter control circuit and the semiconductor optical amplifier driving circuit, so as to make the linear relationship between the central wavelength of the calibrated frequency sweeping laser output laser and the driving voltage of the Fabry-Perot filter more accurate, thereby improving the accuracy of the demodulation of the central wavelength of the fiber grating array unit. At the same time, each driving circuit and the signal generating circuit are integrated during the design, so as to further reduce the volume of the light source and the demodulation equipment, so as to make it suitable for the scene of actual engineering application;

[0024] 3. The present invention fixes the central wavelength of the fiber Bragg grating sensor in the reference optical path unit, compares the demodulation data with the default value when the external environment changes, and performs error compensation on the demodulation module unit, thereby avoiding the influence of the external environment on the demodulation work, ensuring the accuracy of the demodulation data, and ensuring the working effect of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a system schematic diagram of a fiber Bragg grating sensing system based on a frequency-sweeping laser provided according to an embodiment of the present invention;

[0026] Figure 2 is a system schematic diagram of a frequency sweeping laser provided according to an embodiment of the present invention;

[0027] Figure 3 It is a schematic diagram of the linear relationship between the central wavelength of the laser output by the frequency-sweeping laser and the driving voltage of the Fabry-Perot filter provided in an embodiment of the present invention.

[0028] In the figure: 1. FPGA main control board; 2. swept frequency laser; 3. reference optical path unit; 4. fiber grating array unit; 5. demodulation module unit; 6. host computer software system; 21. Fabry-Perot filter; 22. first fiber coupler; 23. semiconductor optical amplifier; 24. second fiber coupler; 25. filter control circuit; 26. semiconductor optical amplifier drive circuit; 31. optical circulator 1; 32. fiber grating sensor; 41. optical circulator 2; 42. multi-channel fiber grating sensor; 51. photoelectric conversion module; 52. filter amplification module; 53. A / D data sampling module; 54. serial communication module. DETAILED DESCRIPTION

[0029] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0030] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships 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. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0031] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0032] like Figure 1-3 As shown, the present invention provides a fiber Bragg grating sensing system based on a frequency sweeping laser, comprising an FPGA main control board 1, a frequency sweeping laser 2, a reference optical path unit 3, a fiber Bragg grating array unit 4, a demodulation module unit 5 and a host computer software system 6; the FPGA main control board 1 is used to control the operation and stop of the entire sensing system; the frequency sweeping laser 2 is connected to the reference optical path unit 3 and the fiber Bragg grating array unit 4, and outputs a tunable laser in the operating state, which passes through the reference optical path unit 3 and the fiber Bragg grating array unit 4 respectively, and is transmitted to the demodulation module unit 5; the demodulation module unit 5 is used to demodulate the sensing signals of the reference optical path unit 3 and the fiber Bragg grating array unit 4 and transmit them to the host computer software system 6, so as to realize sensing and monitoring of the environment.

[0033] Specifically, the present invention uses a self-built sweeping laser 2 to provide a sweeping laser, which can not only act as a light source to further reduce the cost of the fiber grating sensing system, but also be applied to the demodulation technology to further improve the demodulation speed, and can be suitable for the rapid acquisition and processing of massive data information. Among them, the sweeping laser 2 can provide a sweeping laser with a sweeping speed of 3MHz, an output power of 50mw, and a central wavelength in the range of 1230-1390nm. The relationship between the central wavelength y of the output laser of the sweeping laser 2 and the driving voltage x of the Fabry-Perot filter 21 is y=1236.83024+3.41476x, thereby having better performance.

[0034] In one embodiment, the frequency sweeping laser 2 includes a Fabry-Perot filter 21, a first fiber coupler 22, a semiconductor optical amplifier 23, a second fiber coupler 24, a filter control circuit 25 and a semiconductor optical amplifier driving circuit 26. The Fabry-Perot filter 21, the first fiber coupler 22 and the semiconductor optical amplifier 23 are sequentially connected through a single-mode optical fiber to form a ring cavity. The second fiber coupler 24 is used to split the output laser of the ring cavity so that it enters the reference optical path unit 3 and the fiber grating array unit 4 respectively. The filter control circuit 25 is used to drive the Fabry-Perot filter 21 and control the temperature of the Fabry-Perot filter 21. The semiconductor optical amplifier driving circuit 26 is used to drive the semiconductor optical amplifier 23 and control the temperature of the semiconductor optical amplifier 23. Optical isolators are installed at both ends of the semiconductor optical amplifier 23 to realize unidirectional transmission of the laser in the cavity and avoid mode competition.

[0035] Among them, optionally, the semiconductor optical amplifier driving circuit 26 uses the FP7103 voltage-controlled constant current source chip and designs the peripheral circuit by itself to drive the semiconductor optical amplifier 23 for current, and uses the MAX1968 temperature control chip and designs the peripheral circuit by itself to make the semiconductor optical amplifier 23 work in the most beneficial state, thereby ensuring the working effect of the device; the Fabry-Perot filter 21 uses potassium sodium niobate piezoelectric ceramics and AL2O3 anti-reflection film, wherein the piezoelectric coefficient of potassium sodium niobate piezoelectric ceramics is 330pC / N, the electromechanical coupling coefficient is 0.61, the Curie temperature is 220°C, the tuning speed of the FP cavity is less than 50ns, the insertion loss is 0.3db, and the fineness is The invention has a central wavelength peak transmittance of 99.7%, and has better working performance. The filter control circuit 25 cooperates with the semiconductor optical amplifier drive circuit 26 to control the frequency sweeping laser 2 to reduce the influence of temperature drift, so that the linear relationship between the central wavelength of the calibrated output laser of the frequency sweeping laser 2 and the driving voltage of the Fabry-Perot filter 21 is more accurate, thereby improving the accuracy of demodulation of the central wavelength of the fiber grating array unit 4. At the same time, each drive circuit and the signal generating circuit are integrated during design to further reduce the volume of the light source and the demodulation equipment, so that it is suitable for actual engineering application scenarios.

[0036] In this embodiment, the physical length of the annular cavity is 25-27 cm.

[0037] Specifically, the time it takes for light to propagate one circle in the ring cavity is approximately:

[0038]

[0039] Where L is the physical length of the ring cavity, n is the refractive index, and C is the propagation speed of light;

[0040] Then the average scanning speed and the instantaneous fastest scanning speed from short wave to long wave are:

[0041] and

[0042] Among them, R S is the scanning range, f is the frequency of the driving signal;

[0043] Then the number of circles that the photon goes through in the ring cavity is:

[0044]

[0045] Wherein, B is a spectrum bandwidth;

[0046] Among them, N>1 must be satisfied to indicate that during the scanning process of the Fabry-Perot filter 21, the same photon can pass through the Fabry-Perot filter 21 again after being amplified. This is an important prerequisite for the formation of a frequency-sweeping laser in the ring cavity, because sufficient stimulated radiation amplification must be obtained. Specifically, first, spontaneous radiation light is generated in the ring cavity under the action of the semiconductor optical amplifier 23, and a small part of the spontaneous radiation light is output through the first fiber coupler 22 and the second fiber coupler 24 in sequence. The remaining vast majority is filtered by the Fabry-Perot filter 21 and enters the input end of the semiconductor optical amplifier 23 along the ring cavity optical path. After the spontaneous radiation light is amplified by the semiconductor optical amplifier 23, it enters the optical path again and then enters the semiconductor optical amplifier 23 for gain amplification multiple times. When the gain is greater than the loss, a stable frequency-sweeping laser output is formed. By changing the tuning voltage of the Fabry-Perot filter 21, the resonant cavity of the Fabry-Perot filter 21 can be changed to achieve a change in the output wavelength of the frequency-sweeping laser 2, thereby achieving a frequency-sweeping function.

[0047] In one embodiment, the reference optical path unit 3 includes an optical circulator 31 and a fiber grating sensor 32 connected to the optical circulator 31, the optical circulator 31 includes one port, two ports and three ports, the one port is a frequency sweeping laser incident port, after the frequency sweeping laser is emitted through the two ports and enters the fiber grating sensor 32, its reflected light is emitted through the three ports to the demodulation module unit 5 for demodulation, the central wavelength of the fiber grating sensor 32 is fixed, and a default value of the central wavelength demodulation data of the reference optical path unit 3 is set in the host computer software system 6, and when the demodulation data of the fiber grating sensor 32 is inconsistent with the default value, error compensation is performed on the demodulation module unit 5.

[0048] Optionally, the central wavelength of the fiber grating sensor 32 is fixed at 1310 nm.

[0049] In one embodiment, the fiber grating array unit 4 includes a plurality of optical circulators 41 and a multi-channel fiber grating sensor 42 connected to the optical circulators 41; the optical circulators 41 include four ports, five ports and six ports; the four ports are frequency sweeping laser incident ports, and after the frequency sweeping laser is emitted through the five ports and enters the multi-channel fiber grating sensor 42, its reflected light is emitted through the six ports to the demodulation module unit 5 for demodulation.

[0050] Specifically, when the external environment affects the operation of the frequency-sweeping laser 2 due to changes in room temperature, etc., the central wavelength of the laser output by the frequency-sweeping laser 2 is different under the same voltage, which affects the demodulation operation. The present invention uses the reference optical path unit 3, and the central wavelength of the fiber grating sensor 32 is fixed, and it is demodulated to obtain a default value of the demodulation data. When the external environment changes, it is demodulated again. When the demodulation data is different from the default value, the demodulation module unit 5 is error compensated, thereby avoiding the influence of the external environment on the demodulation operation, ensuring the accuracy of the demodulation data, and ensuring the working effect of the device.

[0051] In one embodiment, the demodulation module unit 5 includes a photoelectric conversion module 51, a filter amplification module 52, an A / D data sampling module 53 and a serial communication module 54 connected in sequence. The reflected light first enters the photoelectric conversion module 51 to convert the optical signal into a voltage signal, and then is input into the filter amplification module 52 to shape and amplify the signal, and then the A / D data sampling module 53 converts the analog signal into a digital signal, and finally transmits the signal to the host computer software system 6 through the serial communication module 54 for processing.

[0052] The photoelectric conversion module 51 uses a PbSe avalanche photodiode, and the concentration of Si doping in the buffer layer, multiplication layer, and charge layer is 1.1×10 18 cm -3 , 0.35×10 16 cm -3 , 8×10 16 cm -3 The absorption layer is PbSe film, and the active area of ​​PbSe film is 0.5×0.5mm 2 , thickness is 36μm, module responsivity is 20A / W, conversion gain is 1×10 5 mV / mW, the noise equivalent power is 1pW / √Hz, and the avalanche diode made of PbSe thin film has the advantages of fast response speed and quick photocurrent reaction speed, which can further improve the demodulation speed and accuracy of the demodulation equipment; optionally, the AD9708 digital-to-analog conversion chip is selected, which has the advantages of high performance, low power consumption and small package.

[0053] In one embodiment, the host computer software system 6 is used to display demodulation information in real time after data processing. Specifically, the principle of data processing by the host computer software system 6 is that when the central wavelength of the laser output by the frequency-sweeping laser 2 corresponds to the central wavelength of the fiber grating array unit 4, the intensity of the reflected light is the largest. When the peak-finding algorithm is used to find the point with the strongest light intensity, the voltage of the driving signal of the Fabry-Perot filter 21 is marked, and then the central wavelength of the laser output by the frequency-sweeping laser 2 when the light intensity is the strongest is obtained, and finally the central wavelength of the reflected light is demodulated.

[0054] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A fiber Bragg grating sensing system based on a frequency-sweeping laser, characterized in that: include: FPGA main control board, frequency sweeping laser, reference optical path unit, fiber grating array unit, demodulation module unit and host computer software system; The FPGA main control board is used to control the operation and stop of the entire sensor system; The frequency sweeping laser is connected to the reference optical path unit and the fiber grating array unit, and outputs tunable laser light in the running state, which is transmitted to the demodulation module unit through the reference optical path unit and the fiber grating array unit respectively; The demodulation module unit is used to demodulate the sensing signals of the reference optical path unit and the fiber grating array unit and transmit them to the host computer software system; The frequency sweeping laser comprises a Fabry-Perot filter, a first fiber coupler, a semiconductor optical amplifier, a second fiber coupler, a filter control circuit and a semiconductor optical amplifier driving circuit. The Fabry-Perot filter, the first fiber coupler and the semiconductor optical amplifier are connected in sequence through a single-mode optical fiber to form a ring cavity. The second fiber coupler is used to split the output laser of the ring cavity so that the laser beam enters the reference optical path unit and the fiber grating array unit respectively. The filter control circuit is used to drive the Fabry-Perot filter and control its temperature. The semiconductor optical amplifier driving circuit is used to drive the semiconductor optical amplifier and control its temperature. Optical isolators are installed at both ends of the semiconductor optical amplifier. The reference optical path unit includes an optical circulator 1 and a fiber Bragg grating sensor connected to the optical circulator 1, wherein the optical circulator 1 includes a first port, a second port and a third port, wherein the first port is a frequency sweeping laser incident port, and after the frequency sweeping laser is emitted through the second port and enters the fiber Bragg grating sensor, its reflected light is emitted through the third port to the demodulation module unit for demodulation; The fiber grating array unit includes a plurality of optical circulators 2 and a multi-channel fiber grating sensor connected to the optical circulators 2; the optical circulators 2 include four ports, five ports and six ports; the four ports are frequency sweeping laser incident ports, and after the frequency sweeping laser is emitted through the five ports and enters the multi-channel fiber grating sensor, its reflected light is emitted through the six ports to the demodulation module unit for demodulation.

2. The fiber Bragg grating sensing system based on frequency-sweeping laser according to claim 1, characterized in that: The physical length of the annular cavity is 25-27 cm.

3. The fiber Bragg grating sensing system based on frequency swept laser according to claim 1, characterized in that: The Fabry-Perot filter uses potassium sodium niobate piezoelectric ceramics and AL2O3 antireflection film; the piezoelectric coefficient of potassium sodium niobate piezoelectric ceramics is 330pC / N, the electromechanical coupling coefficient is 0.61, the Curie temperature is 220°C, the tuning speed of the FP cavity is less than 50ns, the insertion loss is 0.3db, the fineness is 5000, the bandwidth is 0.012nm, and the central wavelength peak transmittance is 99.7%; The swept frequency laser can provide a swept frequency laser with a sweeping speed of 3 MHz, an output power of 50 mw, and a central wavelength in the range of 1230-1390 nm. The relationship between the central wavelength y of the output laser of the swept frequency laser and the driving voltage x of the Fabry-Perot filter is y = 1236.83024 + 3.41476x.

4. The fiber Bragg grating sensing system based on frequency swept laser according to claim 1, characterized in that: The demodulation module unit includes a photoelectric conversion module, a filtering and amplifying module, an A / D data sampling module and a serial communication module connected in sequence. The reflected light first enters the photoelectric conversion module to convert the optical signal into a voltage signal, and then is input into the filtering and amplifying module to shape and amplify the signal. The A / D data sampling module then converts the analog signal into a digital signal, and finally transmits the signal to the host computer software system through the serial communication module for processing.

5. The fiber Bragg grating sensing system based on frequency swept laser according to claim 1, characterized in that: The central wavelength of the fiber Bragg grating sensor is fixed, and a default value of the central wavelength demodulation data of the reference optical path unit is set in the host computer software system. When the demodulation data of the fiber Bragg grating sensor is inconsistent with the default value, error compensation is performed on the demodulation module unit.

6. The fiber Bragg grating sensing system based on frequency swept laser according to claim 1, characterized in that: The host computer software system is used to display the demodulated information in real time after data processing.

7. The fiber Bragg grating sensing system based on frequency-sweeping laser according to claim 4, characterized in that: The photoelectric conversion module uses a PbSe avalanche photodiode, and the concentrations of Si doping in the buffer layer, multiplication layer, and charge layer are respectively , , The absorption layer is PbSe film, and the active area of ​​PbSe film is , thickness is 36μm, module responsivity is 20A / W, conversion gain is mV / mW, and the noise equivalent power is 1 pW / √Hz.

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