Grating demodulation method and system

Abstract

The invention provides a grating demodulation method and system. The method comprises the following steps: acquiring a transmission spectrum of an optical fiber Fabry-Perot etalon and a reflection spectrum or transmission spectrum of a reference grating; determining the current environment temperature based on a pre-stored mapping relation according to the position information of the spectral characteristics of the reference grating between the spectral peaks of the transmission spectrum of the optical fiber Fabry-Perot etalon; the mapping relationship is a corresponding relationship between the spectral peak wavelength of the optical fiber Fabry-Perot etalon and the temperature, and a corresponding relationship between the central wavelength of the reference grating and the temperature; according to the current environment temperature and the mapping relation, temperature calibration is carried out on the transmission spectrum of the optical fiber Fabry-Perot etalon to obtain the spectrum peak wavelength after calibration of the optical fiber Fabry-Perot etalon, wavelength calculation is carried out on the reflection spectrum of the to-be-measured optical fiber grating to obtain the center wavelength after calibration of the to-be-measured optical fiber grating, and the to-be-measured optical fiber grating is obtained. The influence of wavelength reference drift of the optical fiber Fabry-Perot etalon caused by temperature is reduced, and the demodulation precision is improved.

Description

Technical Field

[0001] This invention relates to the technical field of grating demodulation, and specifically to a grating demodulation method and system. Background Technology

[0002] Fiber Bragg grating (FBG) sensors detect physical quantities such as temperature and strain by varying the center wavelength of their reflected or transmitted light. They offer advantages such as resistance to electromagnetic interference and ease of networking and multiplexing, and have been widely applied in critical fields such as structural health monitoring, oil and gas well exploration, and aerospace. To achieve accurate demodulation of the FBG's center wavelength, a frequency sweep demodulation scheme based on a tunable Fabry-Perot (FP) filter has become one of the mainstream technologies. In this scheme, a fiber Fabry-Perot (FP) etalon is typically introduced as a wavelength reference. Its known and stable transmission spectrum peak sequence is used as a scale to calibrate the wavelength demodulation errors introduced by nonlinear effects such as hysteresis and creep during the scanning process of the tunable FP filter, thereby improving measurement accuracy.

[0003] However, the transmission peak wavelength of the FP etalon itself drifts with ambient temperature. This temperature drift causes the scale itself, which serves as the reference, to become inaccurate, thus introducing systematic errors into the demodulation results and severely affecting the final measurement accuracy. Existing technologies employ two approaches: firstly, using highly stable FP etalons made of materials with ultra-low coefficients of thermal expansion (such as zero-expansion glass) to physically reduce the temperature drift coefficient; secondly, integrating high-precision active temperature control devices (such as a closed-loop control system consisting of a thermoelectric cooler (TEC) and a temperature sensor) externally to maintain its operating temperature at a set point.

[0004] However, both of these existing technical solutions have significant drawbacks. The manufacturing process of high-stability FP etalons is complex and costly, and its temperature drift coefficient can only be reduced but not completely eliminated. In wide temperature range or high-precision applications, it may still introduce non-negligible errors. Although the second solution can effectively control the temperature, the additional temperature control module greatly increases the complexity, power consumption, cost and size of the system. At the same time, it introduces unstable factors such as temperature control circuit noise and thermal management delay, which is contrary to the development direction of fiber optic sensing systems that pursue miniaturization, low power consumption and high reliability.

[0005] Therefore, existing technologies lack a fiber grating demodulation scheme that can compensate for FP etalon wavelength reference drift caused by temperature changes in real time and accurately without introducing a complex external temperature control system or significantly increasing costs. Thus, existing technologies require further development. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a grating demodulation method and system to solve the problems existing in the prior art.

[0007] To achieve the above-mentioned technical objectives, according to a first aspect of the present invention, a grating demodulation method is provided, employing a grating demodulation system. The grating demodulation system includes a tunable light source and a first optical path component for receiving the output light from the tunable light source. The first optical path component includes a fiber Fabry-Perot etalon and a reference grating located in the same temperature environment. The first optical path component guides the output light through the fiber Fabry-Perot etalon and the reference grating and outputs two optical signals. The two optical signals can be used to analyze and obtain the transmission spectrum of the fiber Fabry-Perot etalon and the optical spectrum of the reference grating. The optical spectrum is either the reflection spectrum or the transmission spectrum of the reference grating. The method includes: S100: Obtain the transmission spectrum of the fiber Fabry-Perot etalon and the optical spectrum of the reference grating; S200. Based on the pre-stored mapping relationship and according to the position information between the spectral peaks of the transmission spectrum of the fiber Fabry-Perot etalon based on the spectral characteristics of the reference grating, determine the current ambient temperature; the mapping relationship includes the correspondence between the spectral peak wavelength of the fiber Fabry-Perot etalon and the temperature, and the correspondence between the center wavelength of the reference grating and the temperature. S300. Based on the current ambient temperature and the mapping relationship, the transmission spectrum of the fiber Fabry-Perot etalon is calibrated by temperature to obtain the calibrated peak wavelength of the fiber Fabry-Perot etalon. Then, using the calibrated peak wavelength, the reflection spectrum of the fiber grating under test is calculated to obtain the calibrated center wavelength of the fiber grating under test.

[0008] Specifically, the grating demodulation system further includes an optical fiber coupler, which is used to split the tunable light source into a first light path and a second light path. The first optical path component further includes a first circulator, which includes a first port, a second port, and a third port. The first light path passes through the fiber Fabry-Perot etalon, enters the first circulator through the first port, and then passes through the second port of the first circulator to the reference grating. After transmission, one light path is output. The reflected light generated by the reference grating outputs another optical signal through the third port. The method for obtaining the transmission spectrum of the fiber Fabry-Perot etalon and the optical spectrum of the reference grating includes: S110. Acquire the first optical signal to be analyzed generated by the transmitted light of the reference grating to the fiber Fabry-Perot etalon under the same temperature environment; S120. Obtain the second optical signal to be analyzed corresponding to the reflected light generated by the reference grating; S130. Based on the first optical signal to be analyzed and the second optical signal to be analyzed, the transmission spectrum of the fiber Fabry-Perot etalon and the reflection spectrum of the reference grating are obtained by analysis.

[0009] Specifically, the step of analyzing and obtaining the transmission spectrum of the fiber Fabry-Perot etalon and the reflection spectrum of the reference grating based on the first optical signal to be analyzed and the second optical signal to be analyzed includes: The first spectrum is obtained based on the first optical signal to be analyzed; The second spectrum is obtained based on the second optical signal to be analyzed; The transmission spectrum of the fiber Fabry-Perot etalon is obtained by adding the first spectrum to the second spectrum. Divide the second spectrum by the transmission spectrum of the fiber Fabry-Perot etalon to obtain the reflection spectrum of the reference grating; The first spectrum comprises a mixed spectrum of the transmission spectrum of the fiber Fabry-Perot etalon and the transmission spectrum of the reference grating, and the second spectrum comprises a mixed spectrum of the transmission spectrum of the fiber Fabry-Perot etalon and the reflection spectrum of the reference grating.

[0010] Specifically, before performing step S100, the method further includes: The fiber Fabry-Perot etalon and the reference grating, both operating under the same temperature environment, are calibrated for ambient temperature. A first mapping relationship between the wavelengths of each spectral peak of the fiber Fabry-Perot etalon and the ambient temperature is established, as well as a second mapping relationship between the center wavelength of the reference grating and the ambient temperature.

[0011] Specifically, the method for determining the current ambient temperature includes: Determine the positional relationship between two adjacent first spectral peaks in the transmission spectrum of the reference grating's center wavelength in the fiber Fabry-Perot etalon; Based on the positional relationship, the first mapping relationship between the wavelengths of the two first spectral peaks and the ambient temperature, and the second mapping relationship between the center wavelength of the reference grating and the ambient temperature, the current ambient temperature is calculated.

[0012] Specifically, the method for calculating the current ambient temperature based on the positional relationship, the first mapping relationship between the wavelengths of the two first spectral peaks and the ambient temperature, and the second mapping relationship between the center wavelength of the reference grating and the ambient temperature includes: The first fiber Fabry-Perot etalon Each spectral peak wavelength With ambient temperature The first mapping relationship is denoted as The center wavelength of the reference grating With ambient temperature The second mapping relationship is denoted as ; Let the two wavelengths corresponding to the two first spectral peaks adjacent to the center wavelength of the reference grating be respectively... , ,but The following positional relationship must be satisfied: ; in, The sampling position is the abscissa of the center wavelength of the reference grating in its own spectrum. and The two first spectral peaks are respectively the abscissa sampling positions of the transmission spectrum of the fiber Fabry-Perot etalon; According to the first mapping relationship Second mapping relationship And the positional relationship formula is used to calculate the current ambient temperature. .

[0013] Specifically, S300 includes: Based on the calculated current ambient temperature Based on the first mapping relationship, the peak wavelength of the transmission spectrum of the temperature-calibrated fiber Fabry-Perot etalon is obtained. ; The peak wavelength of the transmission spectrum of the temperature-calibrated fiber Fabry-Perot etalon The wavelength of the reflection spectrum of the fiber grating under test is calculated to obtain the calibrated center wavelength of the fiber grating. The calculation method is as follows: ; in, The center wavelength of the fiber grating under test after calibration is specified; specifically, it is the center wavelength of a particular fiber grating under test after calibration. To obtain the abscissa sampling position of the center wavelength of a certain fiber grating under test in the sensing spectrum by peak finding, and These are the abscissa sampling positions corresponding to the center wavelength of the sensing spectrum of the fiber grating under test. The abscissa sampling positions of two adjacent spectral peaks in the transmission spectrum of the temperature-calibrated fiber Fabry-Perot etalon 10.

[0014] According to a second aspect of the present invention, a grating demodulation system is provided, comprising: A tunable light source for outputting tunable light; The first fiber optic coupler is used to split the tunable light output from the tunable light source into a first light path and a second light path. The first optical path component includes a fiber Fabry-Perot etalon and a reference grating. The first optical path component is used to guide the first light through the fiber Fabry-Perot etalon and the reference grating and output two optical signals. The two optical signals can be used to analyze and obtain the transmission spectrum of the fiber Fabry-Perot etalon and the optical spectrum of the reference grating. The second optical path assembly includes a modulator, a second circulator, and a fiber optic grating under test. The second circulator includes a fourth port, a fifth port, and a sixth port. The second optical path assembly is used to guide the second light path to be modulated by the modulator, enter the second circulator through the fourth port, and then be incident on the fiber optic grating under test through the fifth port. The reflected light generated by the fiber optic grating under test returns to the second circulator and is output through the sixth port. The photoelectric detection component is used to receive the reflected light from the fiber grating under test output from the sixth port and the two optical signals output from the first optical path component, and convert them into corresponding electrical signals. A data acquisition card is used to acquire the electrical signals output by the photoelectric detection component; The data processing unit is used to process the signals acquired by the data acquisition card and to calculate the wavelength of the reflection spectrum of the fiber optic grating under test according to the above-mentioned grating demodulation method, so as to obtain the center wavelength of the fiber optic grating under test after calibration.

[0015] Specifically, the fiber Fabry-Perot etalon and the reference grating are connected by a thermal coupling structure so that the Fabry-Perot etalon and the reference grating are in the same temperature environment.

[0016] Specifically, the first optical path component further includes a first circulator, which includes a first port, a second port and a third port. The first light passes through the fiber Fabry-Perot etalon, enters the first circulator through the first port, and then is incident on the reference grating through the second port and outputs an optical signal after transmission. The reflected light generated by the reference grating outputs another optical signal through the third port. Alternatively, the first optical path component may further include a first circulator, which includes a first port, a second port, and a third port. The first light enters the first circulator through the first port, then enters the fiber Fabry-Perot etalon through the second port and is transmitted to output an optical signal. The reflected light generated by the fiber Fabry-Perot etalon is entered through the third port and enters the reference grating and is transmitted to output another optical signal. Alternatively, the first optical path component may further include a first circulator, which includes a first port, a second port, and a third port. After the first light passes through the reference grating, it enters the first circulator through the first port, and then is incident on the fiber Fabry-Perot etalon through the second port and outputs one optical signal after transmission. The reflected light generated by the fiber Fabry-Perot etalon outputs another optical signal through the third port. Alternatively, the first optical path component may further include a first circulator, which includes a first port, a second port and a third port. The first light enters the first circulator through the first port, then is incident on the reference grating through the second port and outputs an optical signal after transmission. The reflected light generated by the reference grating is incident on the fiber Fabry-Perot etalon through the third port and outputs another optical signal after transmission. Alternatively, the first optical path assembly may further include a second fiber coupler. After the first light is incident on the second fiber coupler, it is split into two parallel optical paths by the second fiber coupler. One path is incident on the fiber Fabry-Perot etalon and outputs an optical signal after transmission. The other path is incident on the reference grating and outputs another optical signal after transmission.

[0017] Beneficial effects: This invention provides a grating demodulation method and system. By acquiring the transmission spectrum of the transmitted light from the fiber Fabry-Perot etalon and the reflection or transmission spectrum of a reference grating, and then based on the positional information of the peaks in the transmission spectrum of the fiber Fabry-Perot etalon according to the characteristics of the reference grating's reflection or transmission spectrum, combined with a pre-stored wavelength-temperature mapping relationship, the current ambient temperature (i.e., the ambient temperature of the fiber Fabry-Perot etalon and the reference grating) is calculated in real time. Based on this, the transmission spectrum of the fiber Fabry-Perot etalon is calibrated for temperature. Finally, the calibrated peak wavelengths are used to accurately calculate and compensate the sensing spectrum of the fiber grating under test. This invention utilizes the spectral coupling relationship between the reference grating and the etalon to achieve self-sensing of temperature. Without relying on external high-precision temperature control devices, it effectively suppresses the influence of temperature-induced wavelength reference drift of the fiber Fabry-Perot etalon, significantly improving demodulation accuracy and further reducing system complexity, cost, and power consumption. Attached Figure Description

[0018] Figure 1 This is a flowchart of the grating demodulation method provided in a specific embodiment of the present invention; Figure 2 This is a schematic diagram of the composition of the grating demodulation device provided in a specific embodiment of the present invention. Figure 3 This is a schematic diagram of the grating demodulation system provided in a specific embodiment of the present invention; Figure 4 This is a transmission spectrum of the fiber Fabry-Perot etalon itself at a certain temperature during the temperature calibration process, provided in a specific embodiment of the present invention. Figure 5 This is a reflection spectrum of the reference grating itself at a certain temperature during the temperature calibration process, provided in a specific embodiment of the present invention. Figure 6 This is the first spectral diagram of the reference grating and fiber Fabry-Perot etalon provided in a specific embodiment of the present invention; Figure 7 This is the second spectral diagram of the reference grating and fiber Fabry-Perot etalon provided in a specific embodiment of the present invention; Figure 8 This is the transmission spectrum of the fiber Fabry-Perot etalon obtained by analysis in a specific embodiment of the present invention; Figure 9 This is the reflection spectrum of the reference grating obtained through analysis, provided in a specific embodiment of the present invention; Figure 10 This is the first connection method between the fiber optic Fabry-Perot etalon and the reference grating provided in a specific embodiment of the present invention; Figure 11 This is a second connection method between the fiber Fabry-Perot etalon and the reference grating in the first optical path assembly provided in a specific embodiment of the present invention; Figure 12 This is the third connection method between the fiber Fabry-Perot etalon and the reference grating in the first optical path assembly provided in the specific embodiment of the present invention; Figure 13 This is the fourth connection method between the fiber Fabry-Perot etalon and the reference grating in the first optical path assembly provided in the specific embodiment of the present invention; Figure 14 This is the fifth connection method between the fiber Fabry-Perot etalon and the reference grating in the first optical path assembly provided in the specific embodiments of the present invention.

[0019] The attached figures are labeled as follows: 1. Light source; 2. Fabry-Perot filter; 3. First fiber coupler; 4. Modulator; 5. Amplifier; 6. First filter; 7. Splitter; 8. Second circulator; 9. Grating array; 10. Fiber Fabry-Perot etalon; 11. First circulator; 12. Reference grating; 13. Photodetector assembly; 14. Data acquisition card; 15. Data processing unit; 16. Second fiber coupler; 17. First port; 18. Second port; 19. Third port. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Other similar embodiments obtained by those skilled in the art based on the embodiments in this application without creative effort should all fall within the scope of protection of this application. Furthermore, directional terms mentioned in the following embodiments, such as "up," "down," "left," and "right," are only for reference to the directions in the accompanying drawings; therefore, the directional terms used are for illustrative purposes and not for limiting the invention.

[0021] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments.

[0022] Example 1 Please see Figure 1 and Figure 3 This embodiment provides a grating demodulation method employing a grating demodulation system. The grating demodulation system includes a tunable light source and a first optical path component for receiving the output light from the tunable light source. The first optical path component includes a fiber Fabry-Perot etalon 10 and a reference grating 12, both operating at the same temperature. The first optical path component guides the output light through the fiber Fabry-Perot etalon 10 and the reference grating 12, outputting two optical signals. These two optical signals can be used to analyze and obtain the transmission spectrum of the fiber Fabry-Perot etalon 10 and the optical spectrum of the reference grating 12. The optical spectrum is either the reflection spectrum or the transmission spectrum of the reference grating 12. The method includes: acquiring the transmission spectrum of the fiber Fabry-Perot etalon 10 and the reference grating 12. The optical spectrum of grating 12; based on a pre-stored mapping relationship and according to the position information between the spectral peaks of the transmission spectrum of the fiber Fabry-Perot etalon 10 according to the spectral characteristics of the reference grating 12, the current ambient temperature is determined; the mapping relationship includes the correspondence between the spectral peak wavelength of the fiber Fabry-Perot etalon 10 and the temperature, and the correspondence between the center wavelength of the reference grating 12 and the temperature; according to the current ambient temperature and the mapping relationship, the transmission spectrum of the fiber Fabry-Perot etalon 10 is calibrated by temperature to obtain the calibrated spectral peak wavelength of the fiber Fabry-Perot etalon 10, and then the wavelength of the reflection spectrum of the fiber grating under test is calculated using the calibrated spectral peak wavelength to obtain the calibrated center wavelength of the fiber grating under test.

[0023] It is understood that in this embodiment, the fiber Fabry-Perot etalon 10 can provide a series of transmission spectral peaks with known intervals, thus serving as a scale for wavelength demodulation. The reference grating 12 acts as a temperature-sensitive built-in sensing unit. The fiber Fabry-Perot etalon 10 and the reference grating are tightly coupled in the optical path space, ensuring they are physically tightly coupled and in the same temperature field. However, since the fiber Fabry-Perot etalon 10 is affected by the current ambient temperature, causing spectral peak drift, it is necessary to compensate for the temperature-induced spectral peak drift during calibration. This is achieved through the fiber optic cable. The analysis of the mixed spectrum of the Fabry-Perot etalon 10 and the reference grating 12 allows the use of temperature information sensed by the reference grating 12 to correct the wavelength drift of the etalon's spectral peak in real time, thereby achieving temperature self-calibration of the fiber optic grating. This technical solution, through the synergistic effect of the reference grating 12 and the fiber Fabry-Perot etalon 10, achieves real-time compensation for the temperature drift of the core wavelength reference of the demodulation system without introducing an external temperature control system. This effectively reduces demodulation errors caused by changes in ambient temperature, significantly improves measurement accuracy, and further simplifies the system structure, greatly reducing costs. For illustrative purposes, the current ambient temperature here refers to the same ambient temperature at which the fiber Fabry-Perot etalon 10 and the reference grating 12 are located.

[0024] See Figure 1 The specific implementation steps of the grating demodulation method in this embodiment are as follows: S100: Obtain the transmission spectrum of the fiber Fabry-Perot etalon 10 and the optical spectrum of the reference grating 12; In some specific embodiments, reference is made to Figure 3 and Figure 10 The grating demodulation system further includes a first fiber coupler 3, which is used to split the tunable light source into a first light path and a second light path. The first optical path component also includes a first circulator 11, which includes a first port 17, a second port 18, and a third port 19. The first light path passes through the fiber Fabry-Perot etalon 10, enters the first circulator 11 through the first port 17, and then is incident on the reference grating 12 through the second port 18 of the first circulator 11. After transmission, one optical signal is output. The reflected light generated by the reference grating outputs another optical signal through the third port 19. Based on the above optical path connection between the fiber Fabry-Perot etalon 10 and the reference grating 12, the method for obtaining the transmission spectrum of the fiber Fabry-Perot etalon 10 and the optical spectrum of the reference grating 12 is as follows: S110: Acquire the first optical signal to be analyzed generated by the transmission light of the reference grating 12 to the fiber Fabry-Perot etalon 10, which is in the same temperature environment; S120: Obtain the second optical signal to be analyzed corresponding to the reflected light generated by the reference grating 12; S130. Based on the first optical signal to be analyzed and the second optical signal to be analyzed, the transmission spectrum of the fiber Fabry-Perot etalon 10 and the reflection spectrum of the reference grating 12 are obtained by analysis.

[0025] In this embodiment, based on the first optical signal to be analyzed and the second optical signal to be analyzed, the transmission spectrum of the fiber Fabry-Perot etalon 10 and the reflection spectrum of the reference grating 12 are obtained by analysis, including: A first spectrum is obtained based on the first optical signal to be analyzed, and a second spectrum is obtained based on the second optical signal to be analyzed; the first spectrum and the second spectrum are added together to obtain the transmission spectrum of the fiber Fabry-Perot etalon 10; the second spectrum is divided by the transmission spectrum of the fiber Fabry-Perot etalon 10 to obtain the reflection spectrum of the reference grating 12.

[0026] It should be noted that, as Figure 7 As shown, the first spectrum comprises a mixed spectrum consisting of the transmission spectrum of the fiber Fabry-Perot etalon 10 and the transmission spectrum of the reference grating 12, such as... Figure 8 As shown, the second spectrum comprises a mixed spectrum consisting of the transmission spectrum of the fiber Fabry-Perot etalon 10 and the reflection spectrum of the reference grating 12.

[0027] Understandably, the core of the above technical solution lies in separating the independent spectral responses of the fiber Fabry-Perot etalon 10 and the reference grating 12 from the mixed signal containing the common spectral characteristics of the two. Figure 2 As shown, this separation process can be based on the following physical principles and signal processing: (1) Composition of mixed optical signals When a narrowband beam of light that has been filtered by the fiber Fabry-Perot standard etalon 10 is incident on the reference beam When grating 12 is activated, signals in two directions are generated simultaneously: a first optical signal to be analyzed (i.e., the signal in the transmission direction) and a second optical signal to be analyzed (i.e., the signal in the reflection direction). The first optical signal to be analyzed is composed of the optical signal transmitted through the reference grating 12, such as... Figure 6 As shown, its spectral morphology is the result of the combined effect (multiplication) of the transmission spectrum of the FP etalon (fiber Fabry-Perot etalon) and the transmission spectrum of the reference grating 12 itself; the second optical signal to be analyzed (i.e., the signal in the reflection direction) is composed of the optical signal reflected by the reference grating 12, as shown in the figure. Figure 7 The spectral morphology shown is the result of the combined effect (multiplication) of the transmission spectrum of the fiber Fabry-Perot etalon 10 and the reflection spectrum of the reference grating 12 itself. (2) Transmission spectrum of the separated fiber Fabry-Perot etalon 10 Since the transmission and reflection behavior of the reference grating 12 follows the law of conservation of energy, that is, at the same wavelength, the sum of its transmittance and reflectance is a constant value (ideally 1). Therefore, adding the first spectrum obtained based on the first optical signal to be analyzed and the second spectrum obtained based on the second optical signal to be analyzed at the corresponding wavelengths precisely cancels out the influence of the transmission and reflection characteristics of the reference grating 12, resulting in the following: Figure 8 The transmission spectrum of the fiber Fabry-Perot etalon 10 shown is finally obtained with spectral lines that are proportional to the independent transmission spectrum of the fiber Fabry-Perot etalon 10, thus successfully separating it and using it as a precise scale for subsequent wavelength calibration. (3) Separate the reflection spectrum of reference grating 12 To obtain the reflection spectrum of the reference grating 12 used for temperature sensing, it is necessary to eliminate the modulation effect of the transmission spectrum of the fiber Fabry-Perot etalon 10 from the second spectrum. Since the two are multiplicative, this can be achieved through division. By performing point-by-point division, the spectral response of the fiber Fabry-Perot etalon 10, which is a common factor, can be effectively removed, and the final spectrum can be extracted as follows: Figure 9 The reflection spectrum of the reference grating 12 shown provides a reliable data basis for the subsequent accurate calculation of the center wavelength position of the reference grating 12.

[0028] Understandably, this embodiment separates the transmission spectrum of the fiber Fabry-Perot etalon 10 by adding and canceling the influence of the reference grating 12; and obtains the reflection spectrum of the reference grating 12 by dividing the second spectrum by the transmission spectrum of the fiber Fabry-Perot etalon 10. These two steps utilize the physical characteristics and mathematical relationships between the signals of the fiber Fabry-Perot etalon 10 and the reference grating 12 to achieve high-fidelity separation of each independent key spectral information from the mixed optical signal without increasing hardware complexity, laying a solid foundation for subsequent accurate temperature inversion and wavelength compensation.

[0029] In this embodiment, before performing step S100 to obtain the transmission spectrum of the fiber Fabry-Perot etalon 10 and the optical spectrum of the reference grating 12, the embodiment further includes calibrating the ambient temperature of the fiber Fabry-Perot etalon 10 and the reference grating 12, which are under the same temperature environment, to establish a first mapping relationship between the wavelengths of each spectral peak of the fiber Fabry-Perot etalon 10 and the ambient temperature, and to establish a second mapping relationship between the center wavelength of the reference grating 12 and the ambient temperature.

[0030] Furthermore, regarding the temperature calibration of the fiber Fabry-Perot etalon 10 and reference grating 12, which was completed during system debugging, it is necessary to separately calibrate the fiber Fabry-Perot etalon 10 and reference grating 12. Specifically, based on the transmission spectrum of the fiber Fabry-Perot etalon 10 and the reflection or transmission spectrum of the reference grating 12, an oil bath (which is a temperature control device that can provide different ambient temperatures for the fiber Fabry-Perot etalon 10 and reference grating 12) can be used to calibrate the fiber Fabry-Perot etalon 10 and reference grating 12 at different temperatures. This will yield the wavelength changes corresponding to each spectral peak under different temperature conditions. When calibrating the reference grating 12, the transmission spectrum of the reference grating 12 can be calibrated. In this case, a long-period fiber grating (LPFG) is required because a short-period fiber grating (FBG) has a larger error. Correspondingly, in this case, the transmission spectrum of the reference grating 12 is obtained in step S200. Of course, some calibration methods can also calibrate the reflection spectrum of the reference grating 12. In this case, a short-period fiber grating (FBG) is required because the reflection spectrum of the FBG has higher peak intensity and narrower bandwidth, providing a more accurate center wavelength reference in reflection mode. Correspondingly, the reflection spectrum of the reference grating 12 is obtained in step S200. In actual operation, the appropriate grating type needs to be selected according to the specific optical path design and accuracy requirements. If the system has high requirements for signal transmission efficiency, using transmission spectrum calibration in combination with a long-period fiber grating can reduce optical energy loss. If higher wavelength measurement accuracy is pursued, the reflection spectrum of the short-period fiber grating is preferred for calibration to take advantage of its excellent wavelength selectivity and stability.

[0031] Taking the first path of light passing through the fiber optic Fabry-Perot etalon 10, entering the first circulator 11 via the first port 17, and then being incident on the reference grating 12 via the second port 18 of the first circulator 11 as an example, as... Figure 4 and Figure 5 As shown, Figure 4 The transmission spectrum of the fiber Fabry-Perot etalon 10 (FP etalon) at a certain temperature during temperature calibration has multiple spectral peaks, each corresponding to a wavelength. Figure 5 During the temperature calibration process, the reflection spectrum of the reference grating 12 at a certain temperature is as follows: ; in, The wavelengths corresponding to all spectral peaks in the fiber Fabry-Perot etalon 10. For the center wavelength of reference grating 12, The ambient temperature.

[0032] S200. Based on the pre-stored mapping relationship and according to the position information between the spectral peaks of the transmission spectrum of the fiber Fabry-Perot etalon 10 according to the spectral characteristics of the reference grating 12, the current ambient temperature is determined; the mapping relationship includes the correspondence between the spectral peak wavelength of the fiber Fabry-Perot etalon 10 and the temperature, and the correspondence between the center wavelength of the reference grating 12 and the temperature. In this embodiment, the method for determining the current ambient temperature includes: Determine the positional relationship between two adjacent first spectral peaks in the transmission spectrum of the fiber Fabry-Perot etalon 10 in the reflection spectrum of the reference grating 12; Based on the positional relationship, the first mapping relationship between the wavelengths of the two first spectral peaks and the ambient temperature, and the second mapping relationship between the center wavelength of the reference grating 12 and the ambient temperature, the current ambient temperature is calculated.

[0033] Furthermore, the fiber optic Fabry-Perot etalon 10... Each spectral peak wavelength With ambient temperature The first mapping relationship is denoted as The center wavelength of the reference grating 12 With ambient temperature The second mapping relationship is denoted as ; For example, Figure 5 The center wavelength of the reference grating 12 in the reflection spectrum of the reference grating 12 at a certain temperature will fall within... Figure 4 Between two adjacent spectral peaks in the transmission spectrum of the fiber Fabry-Perot etalon 10 at a certain temperature, let the two wavelengths corresponding to the two first spectral peaks adjacent to the center wavelength of the reference grating 12 be respectively... , ,but The following positional relationship must be satisfied: ; in, The sampling position of the center wavelength of the reference grating 12 in its own spectrum is the horizontal coordinate, i.e., the position number in the spectral data sequence. and The two first spectral peaks are respectively the abscissa sampling positions of the transmission spectrum in the fiber Fabry-Perot etalon 10. The above formula, except for temperature... All the other quantities are known, so the ambient temperature can be solved using the above formula. Thus, the ambient temperature is obtained. The wavelength corresponding to the spectral peak of the transmission spectrum of the accurate fiber Fabry-Perot etalon 10 can then be used to more accurately measure the center wavelength in the fiber grating under test, i.e., according to the first mapping relationship, it is denoted as... Second mapping relationship And the positional relationship formula is used to calculate the current ambient temperature. Explanatory, current ambient temperature. It is the ambient temperature at which the fiber optic Fabry-Perot etalon 10 and the reference grating 12 coexist.

[0034] In some specific embodiments, when the temperature variation range is not particularly large (≤300℃), the relationship between the center wavelengths corresponding to the spectral peaks of the fiber Fabry-Perot etalon 10 and the reference grating 12 and the ambient temperature can be considered linear, and the temperature drift coefficient of the spectral peaks of the fiber Fabry-Perot etalon 10 is... equal( Then we have: ; The current ambient temperature can be calculated. 0 is: ; in, The temperature drift coefficient of the spectral peak of the Fabry-Perot etalon 10 fiber is represented. The constant term representing the fiber Fabry-Perot etalon 10, The coefficients representing the transmission or reflection spectrum of the reference grating 12. This represents the constant term of the reference grating 12, which allows for calibration of the sensing spectrum of the fiber optic grating under test based on the current ambient temperature.

[0035] S300. Based on the current ambient temperature and the mapping relationship, the transmission spectrum of the fiber Fabry-Perot etalon 10 is calibrated by temperature to obtain the calibrated peak wavelength of the fiber Fabry-Perot etalon 10. Then, using the calibrated peak wavelength, the reflection spectrum of the fiber grating under test is calculated to obtain the calibrated center wavelength of the fiber grating under test.

[0036] Furthermore, in this embodiment, based on the calculated current ambient temperature... Based on the first mapping relationship, the peak wavelength of the transmission spectrum of the temperature-calibrated fiber Fabry-Perot etalon 10 is obtained. The peak wavelength of the transmission spectrum of the temperature-calibrated fiber Fabry-Perot etalon 10 was determined. The wavelength of the reflection spectrum of the fiber grating under test is calculated to obtain the calibrated center wavelength of the fiber grating. The specific calculation method is as follows: ; in, The center wavelength of the fiber grating under test after calibration is specified; specifically, it is the center wavelength of a particular fiber grating under test after calibration. To obtain the abscissa sampling position of the center wavelength of a certain fiber grating under test in the sensing spectrum by peak finding, and These are the abscissa sampling positions corresponding to the center wavelength of the sensing spectrum of the fiber grating under test. The abscissa sampling positions of two adjacent spectral peaks in the transmission spectrum of the temperature-calibrated fiber Fabry-Perot etalon 10. Explanatoryly, the abscissa of the sensed spectrum is aligned with that of the temperature-calibrated fiber Fabry-Perot etalon 10; other existing alignment methods are not described further.

[0037] It should be noted that this embodiment provides a grating demodulation method. By acquiring a first optical signal to be analyzed generated by the transmission light of the fiber Fabry-Perot etalon 10 through the reference grating 12 in the same temperature environment, and a second optical signal to be analyzed corresponding to the reflected light generated by the reference grating 12, the transmission spectrum of the fiber Fabry-Perot etalon 10 and the reflection spectrum or transmission spectrum of the reference grating 12 are obtained based on the first and second optical signals to be analyzed. Then, based on the position information of the spectral characteristics of the reference grating 12 between the peaks of the transmission spectrum of the fiber Fabry-Perot etalon 10, combined with the pre-stored wavelength-temperature mapping relationship, the current ambient temperature is inferred in real time, and the transmission spectrum of the fiber Fabry-Perot etalon 10 is calibrated accordingly. Finally, the calibrated peak wavelengths are used to achieve accurate calculation and compensation of the sensing spectrum of the fiber grating under test. It utilizes the spectral coupling relationship between the reference grating 12 and the fiber Fabry-Perot etalon 10 to achieve temperature self-sensing. Without relying on external high-precision temperature control devices, it effectively suppresses the influence of temperature-induced wavelength reference drift of the fiber Fabry-Perot etalon 10, significantly improves demodulation accuracy, and further reduces system complexity, cost, and power consumption.

[0038] Example 2 Please see Figure 2 This embodiment provides a grating demodulation device, the device comprising: Acquisition module 100: used to acquire the transmission spectrum of the fiber Fabry-Perot etalon 10 and the optical spectrum of the reference grating 12, wherein the optical spectrum is the reflection spectrum or transmission spectrum of the reference grating 12; Data processing module 200: used to determine the current ambient temperature based on a pre-stored mapping relationship and according to the position information between the spectral peaks of the transmission spectrum of the fiber Fabry-Perot etalon 10 based on the spectral characteristics of the reference grating 12; the mapping relationship includes the correspondence between the spectral peak wavelengths of the fiber Fabry-Perot etalon 10 and the temperature, and the correspondence between the center wavelength of the reference grating 12 and the temperature. Temperature compensation module 300: used to perform temperature calibration on the transmission spectrum of the fiber Fabry-Perot etalon 10 according to the current ambient temperature and the mapping relationship, to obtain the calibrated peak wavelength of the fiber Fabry-Perot etalon 10, and then use the calibrated peak wavelength to perform wavelength calculation on the reflection spectrum of the fiber grating under test to obtain the calibrated center wavelength of the fiber grating under test.

[0039] It should be noted that this embodiment provides a grating demodulation device, which clearly realizes the entire process of the method in Embodiment 1 through modular design. In actual implementation, the acquisition module 100 can specifically correspond to the signal acquisition unit including the photoelectric detection component 13 and the data acquisition card 14. It is responsible for capturing and digitizing the spectral electrical signals generated by the fiber Fabry-Perot etalon 10 and the reference grating 12 in the same temperature field in real time. The data processing module 200 is usually implemented by an embedded processor, microcontroller or computer system. Its embedded algorithm program performs the core signal separation, spectral peak positioning, position information extraction and temperature inversion calculation. The temperature compensation module 300 is also implemented by the processing unit. It calls the pre-stored calibration data according to the inverted real-time ambient temperature, completes the dynamic calibration of the etalon spectral peak, and finally applies the calibrated wavelength scale to the solution of the sensing grating spectrum, and outputs the accurate physical quantity after temperature compensation.

[0040] In this embodiment, the modules work together through a clear data interface. The acquisition module provides the raw signal to the data processing module 200. After the data processing module 200 completes the temperature calculation, it transmits the current temperature value to the temperature compensation module 300. The temperature compensation module uses this calibration parameter to uniformly correct the spectral data of all sensing channels. This architecture enables the system to automatically and continuously complete temperature drift compensation in complex field environments without manual intervention or additional temperature control hardware. This significantly improves the long-term stability, reliability, and measurement accuracy of the fiber Bragg grating demodulation system, while maintaining the system's compactness and economy.

[0041] Example 3 Please see Figure 3 This embodiment provides a grating demodulation system, including: A tunable light source for outputting tunable light; The first fiber optic coupler 3 is used to split the tunable light output from the tunable light source into a first light path and a second light path. The first optical path component includes a fiber Fabry-Perot etalon 10 and a reference grating 12, which are in the same temperature environment. The first optical path component is used to guide the first light through the fiber Fabry-Perot etalon 10 and the reference grating 12 and output two optical signals. The two optical signals can be used to analyze and obtain the transmission spectrum of the fiber Fabry-Perot etalon 10 and the optical spectrum of the reference grating 12. The optical spectrum is the reflection spectrum or the transmission spectrum of the reference grating 12. The second optical path assembly includes a modulator 4, a second circulator 8, and a fiber optic grating under test. The second circulator 8 includes a fourth port, a fifth port, and a sixth port. The second optical path assembly is used to guide the second light path to be modulated by the modulator 4, enter the second circulator 8 through the fourth port, and then be incident on the fiber optic grating under test through the fifth port. The reflected light generated by the fiber optic grating under test returns to the second circulator 8 and is output through the sixth port. Preferably, the fiber grating to be tested can be as follows: Figure 2 The fiber grating array 9 shown; The photoelectric detection component 13 is used to receive the reflected light from the fiber optic grating under test output from the sixth port and the two optical signals output from the first optical path component, and convert them into corresponding electrical signals. The two optical signals output from the first optical path component can be used to analyze and obtain the transmission spectrum of the fiber Fabry-Perot etalon 10 and the transmission or reflection spectrum of the reference grating 12. The photoelectric detection component 13 can be a multi-channel photodetector or a combination of multiple single-channel photodetectors, as long as they can individually receive their respective optical signals.

[0042] Data acquisition card 14 is used to acquire the electrical signals output by the photoelectric detection component 13; The data processing unit 15 is used to process the signal acquired by the data acquisition card 14 and perform wavelength calculation on the reflection spectrum of the fiber optic grating under test according to the grating demodulation method described in any of the above embodiments, so as to obtain the center wavelength of the fiber optic grating under test after calibration.

[0043] It should be further explained that, see [link / reference] Figure 3In this embodiment, the tunable light source includes a light source 1 and a Fabry-Perot filter 2. The Fabry-Perot filter 2 is used to filter the light emitted by the light source 1. The light source 1 is a broadband light source that can output light with a wide wavelength range. The Fabry-Perot filter 2 can selectively transmit light of a specific wavelength. The first fiber coupler 3 can split the light from the light source 1 into x% and y% (x+y=100). It can output a portion of the light to the fiber grating under test as probe light and output the other portion of the light to the first optical path component as compensation light for subsequent wavelength calibration. Furthermore, the first optical path component includes a fiber Fabry-Perot etalon 10 and a reference grating 12. In some specific embodiments, the first optical path component may also include a first circulator 11. When the first light passes through the fiber Fabry-Perot etalon 10, a standing wave is generated in the cavity. This standing wave can serve as a scale to measure the wavelength change of the sensing channel. The reference grating 12 may be a short-period fiber grating, which works in conjunction with the fiber Fabry-Perot etalon 10 to measure temperature and calibrate wavelength.

[0044] In some embodiments, the fiber Fabry-Perot etalon 10 and the reference grating 12 are connected by a thermal coupling structure, that is, the fiber Fabry-Perot etalon 10 and the reference grating 12 are integrated into the same package, or they are fixed to the same substrate by a thermally conductive material, so that the Fabry-Perot etalon 10 and the reference grating 12 are in the same temperature environment. This design can effectively avoid measurement errors caused by temperature differences, ensure that the two maintain synchronous response when the temperature changes, and because they are in the same temperature environment, the temperature-induced wavelength drift has a high degree of consistency.

[0045] Furthermore, in some specific embodiments, the second optical path assembly includes a modulator 4, an amplifier 5, a first filter 6, a splitter 7, multiple second circulators 8, and multiple fiber gratings under test connected in sequence. The modulator 4 modulates the second light stream split from the first fiber coupler 3 into pulsed light. The amplifier 5 amplifies the optical signal power of the pulsed light. The first filter 6 performs noise reduction filtering on the optical signal to reduce the noise after amplification by the amplifier 5. The splitter 7 is a 1×N fiber splitter 7, capable of dividing the light source 1 into N channels. After the second light stream passes through the modulator 4, amplifier 5, and first filter 6 in sequence, it is split into multiple channels by the splitter 7. Each channel is connected to a second circulator 8, and then the light is incident on the fiber grating under test in each channel through the second circulator 8. The fiber grating under test can be a grating of different wavelengths, or it can be composed of several identical or cascaded ultra-weak gratings with a center wavelength spacing.

[0046] In a preferred embodiment, the grating demodulation system operates as follows: like Figure 3 As shown, light source 1 emits narrowband continuous light through the FP cavity of Fabry-Perot filter 2, which is split into two paths by the first fiber coupler 3. One path enters the fiber Fabry-Perot etalon 10, the first circulator 11, and the reference grating 12 for wavelength calibration; the other path enters the modulator 4 to form narrowband pulse light, which is then amplified and filtered by amplifier 5 and the first filter 6, and then enters the fiber grating under test through splitter 7 and the second circulator 8. The time-division multiplexed reflected light of the fiber grating under test enters the photodetector 13 through the second circulator 8. The photodetector 13 can detect the time-division multiplexed reflected light of the narrowband pulse light from the fiber grating under test. To emit narrowband continuous light with different center wavelengths, the center wavelength of the narrowband continuous light can be changed by controlling the cavity length of the Fabry-Perot filter 2 to perform wavelength scanning and obtain the corresponding narrowband continuous light. Then, the narrowband continuous light is modulated by the modulator 4 to form the corresponding narrowband pulse light. The narrowband pulse light is reflected by the fiber grating under test to generate time-division multiplexed reflected light. The time-division multiplexed reflected light is received by the photodetector 13, which can detect the time-division multiplexed reflected light of the narrowband pulse light. Then, through the sampling of the data acquisition card 14 and the data processing calculation of the data processing unit 15, the reflection intensity change of the fiber grating under test to the narrowband pulse light with different center wavelengths is obtained, thereby plotting the spectrum of each grating in the fiber grating under test, collectively referred to as the sensing grating spectrum (e.g., 1510nm, 1520nm, 1530nm, 1570nm, each center wavelength will generate a sampling point of the spectrum for each grating in the fiber grating under test). Wavelength calibration of the grating spectrum (spectrum of fiber optic grating array 9) is performed based on the spectral peaks of one path of the fiber Fabry-Perot etalon 10 and the reference grating 12 to reduce demodulation errors. This demodulation system uses the fiber Fabry-Perot etalon 10, the first circulator 11, and the reference grating 12 to calibrate the wavelength, eliminating the effects of nonlinear errors such as hysteresis and creep during the tuning of the FP cavity of the Fabry-Perot filter 2. However, the fiber Fabry-Perot etalon 10 is affected by ambient temperature, which can cause spectral peak drift. Therefore, it is necessary to compensate for the temperature-induced peak drift of the fiber Fabry-Perot etalon 10 and the reference grating 12 during the calibration process to accurately calibrate the wavelength and improve demodulation accuracy. This can be achieved by using the grating demodulation method described in Example 1 to compensate for the temperature-induced peak drift, thereby obtaining the wavelength of the calibrated sensing spectrum.

[0047] In some specific embodiments, see Figures 10-14The optical path connection between the fiber Fabry-Perot etalon 10 and the reference grating 12 can be designed in various ways, as long as both are kept in the same temperature environment and the transmission spectrum of the fiber Fabry-Perot etalon 10 and the optical spectrum of the reference grating 12 can be obtained for subsequent processing. The specific connection methods are as follows: In the first preferred embodiment, see Figure 3 and Figure 10 The first optical path component includes a first circulator 11, which includes a first port 17, a second port 18, and a third port 19. The first light output from the first fiber coupler 3 passes through the fiber Fabry-Perot etalon 10, enters the first circulator 11 through the first port 17, and then passes through the second port 18 of the first circulator 11 to the reference grating 12. After transmission, one optical signal is output. The reflected light generated by the reference grating is output through the third port 19 as another optical signal. Both optical signals are output to the downstream photodetector component 13. For the specific spectral analysis method, please refer to the description in the preferred embodiment above.

[0048] In the second preferred embodiment, Figure 3 The first optical path component has been improved based on the previous embodiment. See also... Figure 11 The first optical path component includes a first circulator 11, which includes a first port 17, a second port 18, and a third port 19. In this embodiment, the first light from the first fiber coupler 3 first enters the first circulator 11 through the first port 17 and is then split into two optical paths. One path passes through the second port 18 and is incident on the fiber Fabry-Perot etalon 10, and after transmission, outputs an optical signal. The other path is reflected light generated by the fiber Fabry-Perot etalon 10 and passes through the third port 19 and is incident on the reference grating 12, and after transmission, outputs another optical signal. The two optical signals output by the first optical path component are respectively output to the downstream photodetector component 13.

[0049] exist Figure 11In this process, the photoelectric detection component 13 receives the transmission spectrum generated by the direct transmission of the fiber Fabry-Perot etalon 10, and the mixed spectrum of the reflection spectrum generated by the fiber Fabry-Perot etalon 10 reflecting the reference grating 12 and the transmission spectrum generated by the direct transmission of the reference grating 12. That is, the first spectrum consists of the optical signal directly transmitted through the fiber Fabry-Perot etalon 10, and the second spectrum consists of the optical signal reflected from the fiber Fabry-Perot etalon 10 and then transmitted through the reference grating 12. Its spectral form is the result of the combined effect (multiplication) of the reflection spectrum of the fiber Fabry-Perot etalon 10 and the transmission spectrum of the reference grating 12 itself. In other words, the transmission spectrum of the fiber Fabry-Perot etalon 10 is the first spectrum. The reflection spectrum of the fiber Fabry-Perot etalon 10 is obtained through energy conservation, and the transmission spectrum of the reference grating 12 is obtained by dividing the second spectrum by the reflection spectrum of the fiber Fabry-Perot etalon 10.

[0050] In the third preferred embodiment, Figure 3 The first optical path component has been improved based on the previous embodiment. See also... Figure 12 The first optical path component includes a first circulator 11, which includes a first port 17, a second port 18, and a third port 19. This method is the reverse of the order of the first preferred embodiment described above. The first light output from the first fiber coupler 3 is first incident on the reference grating 12, then enters the first circulator 11 through the first port 17, and then is incident on the fiber Fabry-Perot etalon 10 through the second port 18 of the first circulator 11. After transmission, one optical signal is output. The reflected light generated by the fiber Fabry-Perot etalon 10 is output through the third port as another optical signal. Both optical signals are output to the downstream photodetector component 13.

[0051] exist Figure 12 In this spectrum, the first spectrum is composed of the light signals transmitted through the reference grating 12 and the optical fiber Fabry-Perot etalon 10. The second spectrum is composed of the light signals reflected by the optical fiber Fabry-Perot etalon 10 after the light transmitted through the reference grating 12. The spectral shape is the result of the combined effect (multiplication) of the reflection spectrum of the optical fiber Fabry-Perot etalon 10 and the transmission spectrum of the reference grating 12 itself. In other words, the transmission spectrum of the optical fiber Fabry-Perot etalon 10 is the first spectrum. The first spectrum and the second spectrum are added together to obtain the transmission spectrum of the reference grating 12. The first spectrum is divided by the transmission spectrum of the reference grating 12 to obtain the transmission spectrum of the optical fiber Fabry-Perot etalon 10.

[0052] In the fourth preferred embodiment, in Figure 3 The first optical path component has been improved based on the previous embodiment. See also... Figure 13The first optical path component includes a first circulator 11, which includes a first port 17, a second port 18, and a third port 19. The first light output from the first fiber coupler 3 enters the first circulator 11 through the first port 17, then is incident on the reference grating 12 through the second port 18 and outputs an optical signal after transmission. The reflected light generated by the reference grating 12 is incident on the fiber Fabry-Perot etalon 10 through the third port 19 and outputs another optical signal after transmission. Then, the two optical signals output by the first optical path component are respectively output to the downstream photodetector component 13. The key difference between this method and the second preferred embodiment is that the positions of the fiber Fabry-Perot etalon 10 and the reference grating 12 are swapped.

[0053] exist Figure 13 In this spectrum, the first spectrum is composed of the light signal transmitted through the reference grating 12, and the second spectrum is composed of the light signal reflected from the reference grating 12 and transmitted through the fiber Fabry-Perot etalon 10. The spectral shape is the result of the combined effect (multiplication) of the reflection spectrum of the reference grating 12 and the transmission spectrum of the fiber Fabry-Perot etalon 10 itself. The transmission spectrum of the reference grating 12 is the first spectrum. The reflection spectrum of the reference grating 12 is obtained through energy conservation. The transmission spectrum of the fiber Fabry-Perot etalon 10 is obtained by dividing the second spectrum by the reflection spectrum of the reference grating 12.

[0054] In the fifth preferred embodiment, see Figure 14 The first optical path assembly also includes a second fiber coupler 16. After the first light output from the first fiber coupler 3 is incident on the second fiber coupler 16, the second fiber coupler 16 splits the first light into two completely independent parallel optical paths. One optical path is incident on the fiber Fabry-Perot etalon 10 and outputs one optical signal after transmission. The other optical path is incident on the reference grating 12 and outputs another optical signal after transmission. The two optical signals are respectively output to the downstream photodetector assembly 13.

[0055] exist Figure 14 In the first spectrum, the transmission spectrum of the reference grating 12 is the transmission spectrum of the fiber Fabry-Perot etalon 10, and the second spectrum is the transmission spectrum of the fiber Fabry-Perot etalon 10.

[0056] It is understandable that the various optical path connection methods provided above allow for flexible design of the topology between the fiber Fabry-Perot etalon 10 and the reference grating 12. Under the premise of ensuring that both are in the same temperature field, both can effectively generate spectral signals containing the spectral characteristics of both. These methods collectively achieve real-time, adaptive temperature drift compensation for the etalon wavelength reference through the temperature compensation algorithm in this invention without introducing external temperature control hardware. This not only significantly improves the measurement accuracy and stability of the demodulation system under various temperature environments, but also provides a high degree of flexibility and engineering applicability in system design by offering multiple optical path configuration options. It allows for optimized trade-offs between system complexity, optical path isolation, signal-to-noise ratio, and cost according to different application scenarios, thereby achieving high-precision and highly robust fiber grating demodulation while maintaining the advantages of compact structure, low power consumption, and low cost.

[0057] It should be noted that this embodiment provides a grating demodulation system. By integrating a tunable light source and a first optical path component containing an optical fiber Fabry-Perot etalon 10 and a reference grating 12 in the same temperature field, a complete hardware platform is constructed to physically implement the temperature compensation method in Embodiment 1, achieving high-precision demodulation. This system utilizes the reference grating 12 as a built-in temperature sensor, and uses an algorithm to invert and compensate for the temperature drift of the etalon in real time, fundamentally suppressing the influence of ambient temperature changes on the wavelength reference standard. This significantly improves the calculation accuracy of the center wavelength of the sensing grating, optimizes the system structure and cost, and eliminates the need for an independent high-precision grating. The device achieves temperature insensitivity while maintaining a high-precision temperature control module. This avoids increased system complexity, power consumption, and size, effectively controls overall cost, and enhances system stability and applicability. The design of multiple optical path connection methods gives the device good engineering flexibility, enabling it to adapt to the requirements of different application scenarios regarding optical path isolation, signal-to-noise ratio, and assembly complexity. At the same time, the device compensates for the nonlinear error of the tunable filter itself by using the fixed spectral peak of the fiber Fabry-Perot etalon 10, further ensuring the stability and reliability of long-term measurements. This results in a miniaturized, low-power, high-precision, and environmentally robust fiber grating demodulation solution.

[0058] Example 4 In a preferred embodiment, this application also provides an electronic device, the electronic device comprising: The computer device includes a memory and a processor, wherein the memory stores computer-readable instructions that, when executed by the processor, implement the raster demodulation method described herein. The computer device can be broadly categorized as a server, terminal, or any other electronic device with the necessary computing and / or processing capabilities. In one embodiment, the computer device may include a processor, memory, network interface, communication interface, etc., connected via a system bus. The processor of the computer device can be used to provide the necessary computing, processing, and / or control capabilities. The memory of the computer device may include a non-volatile storage medium and internal memory. The non-volatile storage medium may store an operating system, computer programs, etc. The internal memory can provide an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The network interface and communication interface of the computer device can be used to connect and communicate with external devices via a network. When the computer program is executed by the processor, it performs the steps of the method of the present invention.

[0059] This invention can be implemented as a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, causes the steps of the methods of embodiments of the invention to be performed. In one embodiment, the computer program is distributed across multiple network-coupled computer devices or processors, such that the computer program is stored, accessed, and executed in a distributed manner by one or more computer devices or processors. A single method step / operation, or two or more method steps / operations, may be executed by a single computer device or processor or by two or more computer devices or processors. One or more method steps / operations may be executed by one or more computer devices or processors, and one or more other method steps / operations may be executed by one or more other computer devices or processors. One or more computer devices or processors may execute a single method step / operation, or execute two or more method steps / operations.

[0060] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0061] The technical features described above can be combined arbitrarily. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be covered by this specification, provided that such combination does not contain contradictions.

[0062] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A grating demodulation method, characterized in that, A grating demodulation system is employed, comprising a tunable light source and a first optical path component for receiving the output light from the tunable light source. The first optical path component includes a fiber Fabry-Perot etalon (10) and a reference grating (12) located in the same temperature environment. The first optical path component guides the output light through the fiber Fabry-Perot etalon (10) and the reference grating (12) and outputs two optical signals. The two optical signals can be used to analyze and obtain the transmission spectrum of the fiber Fabry-Perot etalon (10) and the optical spectrum of the reference grating (12). The optical spectrum is the reflection spectrum or transmission spectrum of the reference grating (12). The method includes: S100: Obtain the transmission spectrum of the fiber Fabry-Perot etalon (10) and the optical spectrum of the reference grating (12); S200. Based on the pre-stored mapping relationship and according to the position information between the spectral peaks of the transmission spectrum of the fiber Fabry-Perot etalon (10) based on the spectral characteristics of the reference grating (12), the current ambient temperature is determined; the mapping relationship includes the correspondence between the spectral peak wavelength of the fiber Fabry-Perot etalon (10) and the temperature, and the correspondence between the center wavelength of the reference grating (12) and the temperature. S300. Based on the current ambient temperature and the mapping relationship, the transmission spectrum of the fiber Fabry-Perot etalon (10) is calibrated by temperature to obtain the calibrated peak wavelength of the fiber Fabry-Perot etalon (10). Then, the calibrated peak wavelength is used to calculate the wavelength of the reflection spectrum of the fiber grating under test to obtain the calibrated center wavelength of the fiber grating under test.

2. The grating demodulation method according to claim 1, characterized in that, The grating demodulation system further includes an optical fiber coupler (3), which is used to split the tunable light output by the tunable light source into a first light path and a second light path. The first optical path component further includes a first circulator (11), which includes a first port (17), a second port (18), and a third port (19). The first light path passes through the fiber Fabry-Perot etalon (10), enters the first circulator (11) through the first port (17), and then is incident on the reference grating (12) through the second port (18) and outputs a light signal after transmission. The reflected light generated by the reference grating (12) outputs another light signal through the third port (19). The method for obtaining the transmission spectrum of the fiber Fabry-Perot etalon (10) and the optical spectrum of the reference grating (12) includes: S110. Acquire the first optical signal to be analyzed generated by the transmitted light from the reference grating (12) to the fiber Fabry-Perot etalon (10) under the same temperature environment; S120. Obtain the second optical signal to be analyzed corresponding to the reflected light generated by the reference grating (12); S130. Based on the first optical signal to be analyzed and the second optical signal to be analyzed, the transmission spectrum of the fiber Fabry-Perot etalon (10) and the reflection spectrum of the reference grating (12) are obtained by analysis.

3. The grating demodulation method according to claim 2, characterized in that, The process of analyzing and obtaining the transmission spectrum of the fiber Fabry-Perot etalon (10) and the reflection spectrum of the reference grating (12) based on the first and second optical signals to be analyzed includes: The first spectrum is obtained based on the first optical signal to be analyzed; The second spectrum is obtained based on the second optical signal to be analyzed; Add the first spectrum to the second spectrum to obtain the transmission spectrum of the fiber Fabry-Perot etalon (10); Divide the second spectrum by the transmission spectrum of the fiber Fabry-Perot etalon (10) to obtain the reflection spectrum of the reference grating (12); The first spectrum includes a mixed spectrum of the transmission spectrum of the fiber Fabry-Perot etalon (10) and the transmission spectrum of the reference grating (12), and the second spectrum includes a mixed spectrum of the transmission spectrum of the fiber Fabry-Perot etalon (10) and the reflection spectrum of the reference grating (12).

4. The grating demodulation method according to claim 1, characterized in that, Before performing step S100, the method further includes: The fiber Fabry-Perot etalon (10) and the reference grating (12) under the same temperature environment are respectively calibrated for ambient temperature, and a first mapping relationship between the wavelengths of each spectral peak of the fiber Fabry-Perot etalon (10) and the ambient temperature is established, as well as a second mapping relationship between the center wavelength of the reference grating (12) and the ambient temperature is established.

5. The grating demodulation method according to claim 4, characterized in that, The method for determining the current ambient temperature includes: Determine the positional relationship between two adjacent first spectral peaks in the transmission spectrum of the reference grating (12) in the fiber Fabry-Perot etalon (10); Based on the positional relationship, the first mapping relationship between the wavelengths of the two first spectral peaks and the ambient temperature, and the second mapping relationship between the center wavelength of the reference grating (12) and the ambient temperature, the current ambient temperature is calculated.

6. The grating demodulation method according to claim 5, characterized in that, The method for calculating the current ambient temperature based on the positional relationship, the first mapping relationship between the wavelengths of the two first spectral peaks and the ambient temperature, and the second mapping relationship between the center wavelength of the reference grating (12) and the ambient temperature includes: The fiber Fabry-Perot etalon (10) is the first Each spectral peak wavelength With ambient temperature The first mapping relationship is denoted as The center wavelength of the reference grating (12) With ambient temperature The second mapping relationship is denoted as ; Let the two wavelengths corresponding to the two first spectral peaks adjacent to the center wavelength of the reference grating (12) be respectively , ,but The following positional relationship must be satisfied: ； in, The sampling position of the center wavelength of the reference grating (12) in its own spectrum is the abscissa. and The two first spectral peaks are respectively the abscissa sampling positions of the transmission spectrum of the fiber Fabry-Perot etalon (10); According to the first mapping relationship Second mapping relationship And the positional relationship formula is used to calculate the current ambient temperature. .

7. The grating demodulation method according to claim 6, characterized in that, The S300 includes: Based on the calculated current ambient temperature Based on the first mapping relationship, the peak wavelength of the transmission spectrum of the temperature-calibrated fiber Fabry-Perot etalon (10) is obtained. ; The peak wavelength of the transmission spectrum of the temperature-calibrated fiber Fabry-Perot etalon (10) The wavelength of the reflection spectrum of the fiber grating under test is calculated to obtain the calibrated center wavelength of the fiber grating. The calculation method is as follows: ； in, The center wavelength of the fiber grating under test after calibration is specified; specifically, it is the center wavelength of a particular fiber grating under test after calibration. To obtain the abscissa sampling position of the center wavelength of a certain fiber grating under test in the sensing spectrum by peak finding, and These are the abscissa sampling positions corresponding to the center wavelength of the sensing spectrum of the fiber grating under test. The abscissa sampling positions of two adjacent spectral peaks in the transmission spectrum of the temperature-calibrated fiber Fabry-Perot etalon (10).

8. A grating demodulation system, characterized in that, include: A tunable light source for outputting tunable light; The first fiber optic coupler (3) is used to split the tunable light output from the tunable light source into a first light path and a second light path. The first optical path component includes a fiber Fabry-Perot etalon (10) and a reference grating (12) in the same temperature environment. The first optical path component is used to guide the first light through the fiber Fabry-Perot etalon (10) and the reference grating (12) and output two optical signals. The two optical signals can be used to analyze and obtain the transmission spectrum of the fiber Fabry-Perot etalon (10) and the optical spectrum of the reference grating (12). The optical spectrum is the reflection spectrum or transmission spectrum of the reference grating (12). The second optical path component includes a modulator (4), a second circulator (8), and a fiber optic grating under test. The second circulator (8) includes a fourth port, a fifth port, and a sixth port. The second optical path component is used to guide the second light to be modulated by the modulator (4), enter the second circulator (8) through the fourth port, and then be incident on the fiber optic grating under test through the fifth port. The reflected light generated by the fiber optic grating under test returns to the second circulator (8) and is output through the sixth port. The photoelectric detection component (13) is used to receive the reflected light from the fiber grating under test output from the sixth port and the two optical signals output from the first optical path component, and convert them into corresponding electrical signals. Data acquisition card (14) is used to acquire the electrical signals output by the photoelectric detection component (13); The data processing unit (15) is used to process the signal acquired by the data acquisition card (14) and perform wavelength calculation on the reflection spectrum of the fiber optic grating under test according to any one of claims 1 to 7, so as to obtain the center wavelength of the fiber optic grating under test after calibration.

9. The grating demodulation system according to claim 8, characterized in that, The fiber Fabry-Perot etalon (10) and the reference grating (12) are connected by a thermal coupling structure so that the fiber Fabry-Perot etalon (10) and the reference grating (12) are in the same temperature environment.

10. The grating demodulation system according to claim 8, characterized in that, The first optical path component further includes a first circulator (11), which includes a first port (17), a second port (18), and a third port (19). The first light passes through the fiber Fabry-Perot etalon (10), enters the first circulator (11) through the first port (17), and then is incident on the reference grating (12) through the second port (18) and outputs one optical signal after transmission. The reflected light generated by the reference grating (12) outputs another optical signal through the third port (19). Alternatively, the first optical path component may further include a first circulator (11), which includes a first port (17), a second port (18), and a third port (19). The first light enters the first circulator (11) through the first port (17), and then enters the fiber Fabry-Perot etalon (10) through the second port (18) and outputs an optical signal after transmission. The reflected light generated by the fiber Fabry-Perot etalon (10) enters the reference grating (12) through the third port (19) and outputs another optical signal after transmission. Alternatively, the first optical path assembly may further include a first circulator (11), which includes a first port (17), a second port (18), and a third port (19). After the first light passes through the reference grating (12), it enters the first circulator (11) through the first port (17), and then enters the fiber Fabry-Perot etalon (10) through the second port (18) and outputs one optical signal after transmission. The reflected light generated by the fiber Fabry-Perot etalon (10) outputs another optical signal through the third port (19). Alternatively, the first optical path component may further include a first circulator (11), which includes a first port (17), a second port (18), and a third port (19). The first light enters the first circulator (11) through the first port (17), then is incident on the reference grating (12) through the second port (18), and outputs an optical signal after transmission. The reflected light generated by the reference grating (12) is incident on the fiber Fabry-Perot etalon (10) through the third port (19) and outputs another optical signal after transmission. Alternatively, the first optical path assembly may further include a second optical fiber coupler (16). After the first light is incident on the second optical fiber coupler (16), it is split into two parallel optical paths by the second optical fiber coupler (16). One path is incident on the fiber Fabry-Perot etalon (10) and outputs an optical signal after transmission. The other path is incident on the reference grating (12) and outputs another optical signal after transmission.

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