Fiber fabry-perot temperature demodulation method based on frequency domain dispersion compensation of interference spectrum

Abstract

The present application belongs to the technical field of optical fiber sensing, and particularly relates to a fiber Fabry-Perot temperature demodulation method based on interference spectrum frequency domain dispersion compensation. The method comprises the following steps: establishing a dispersion simulation model, and numerically solving a dispersion compensation function; collecting an interference spectrum signal of a fiber Fabry-Perot temperature sensor to be measured, performing Fourier spectrum analysis to obtain a Fourier frequency domain signal amplitude spectrum, and extracting a wave peak to obtain a value of a dispersion interference cavity; compensating to obtain a value of a non-dispersion interference cavity according to the dispersion compensation function; calculating an interference fringe of a single interference cavity from the Fourier frequency domain signal amplitude spectrum; calculating a wrapped phase and a rough interference fringe order of the interference fringe of the single interference cavity; and calculating an optical path difference according to the wrapped phase and the rough interference fringe order. The present application builds a spectrum signal collection and demodulation system with a spectrometer as a core, and adds dispersion compensation in the demodulation process. Compared with a traditional method, the present application can effectively eliminate the order jump problem caused by dispersion effect.

Description

Technical Field

[0001] This invention belongs to the field of fiber optic sensing technology, specifically relating to a fiber optic Fabry-Perot temperature demodulation method based on interferometric spectral frequency domain dispersion compensation. Background Technology

[0002] Fiber optic Fabry-Perot temperature sensors are widely used in harsh industrial environments due to their small size, high sensitivity, strong corrosion resistance, and strong electromagnetic interference resistance. Accurate demodulation of the interference spectrum signal is crucial for the accurate measurement of fiber optic Fabry-Perot temperature sensors. Spectral demodulation, with its high accuracy and large dynamic range, is widely used for Fabry-Perot cavity length demodulation. To meet the demodulation requirements of high resolution and large dynamic range, the commonly used spectral demodulation method is as follows: Fourier spectrum analysis is performed on the interference spectrum signal to find the peak in the amplitude spectrum; the peak position is used as the coarse optical path difference of the interference cavity; bandpass filtering is applied to the interference cavity position of the Fourier spectrum signal, followed by inverse Fourier transform to obtain the interference fringes of a single interference cavity; the coarse optical path difference is divided by the peak wavelength of the filtered interference fringes to calculate the coarse fringe order; the coarse fringe order is rounded to obtain the accurate fringe order, which is then multiplied by the peak wavelength to obtain the accurate optical path difference. However, during the demodulation process, the algorithm experiences a phase jump due to the dispersion effect of the cavity material, which affects the measurement results of the fiber optic Fabry-Perot temperature sensor.

[0003] Current research on Fabry-Perot cavity dispersion mainly focuses on the generation of optical frequency combs. Existing techniques have achieved ultra-flat, low-noise comb-shaped spectra in fiber Fabry-Perot resonators by optimizing group velocity dispersion and third-order dispersion. However, they have not addressed the phase jump caused by the dispersion effect of the cavity material. This phase jump still affects the measurement and demodulation results of fiber Fabry-Perot temperature sensors. Therefore, this invention proposes a fiber Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation using interferometric spectroscopy. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in related technologies. To this end, this invention provides a fiber optic Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation of interferometric spectra, which can overcome the phase jump problem caused by dispersion effects, providing a highly competitive technical solution for fiber optic Fabry-Perot temperature sensing demodulation.

[0005] This invention provides a fiber optic Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation of interferometric spectra, comprising the following steps:

[0006] S1: Establish a dispersion simulation model and numerically solve the dispersion compensation function;

[0007] S2: Acquire the interference spectrum signal of the fiber optic Fabry-Perot temperature sensor under test, and perform Fourier spectrum analysis to obtain the Fourier frequency domain signal amplitude spectrum;

[0008] S3: Extract the peak of the amplitude spectrum of the Fourier frequency domain signal to obtain the value of the dispersive interference cavity;

[0009] S4: Calculate the value of the dispersion-free state after compensation based on the dispersion compensation function and the value of the dispersive interference cavity;

[0010] S5: Based on the value of the non-dispersion signal after compensation and the amplitude spectrum of the Fourier frequency domain signal, bandpass filtering and inverse Fourier transform are performed to obtain the interference fringes of a single interference cavity.

[0011] S6: Calculate the enclosed phase and coarse interference fringe order of the single interference cavity;

[0012] S7: The precise fringe order is calculated from the coarse interference fringe order, and the precise optical path difference is calculated from the precise fringe order and the enclosed phase.

[0013] According to the present invention, a fiber optic Fabry-Perot temperature demodulation method based on interferometric spectral frequency domain dispersion compensation is provided, wherein step S1 includes:

[0014] S11: Place the fiber optic Fabry-Perot temperature sensor under test in a specific temperature environment and collect the interference spectrum signal;

[0015] S12: Perform a mapping transformation on the wavenumber of the interference spectrum signal, and construct the mapped spectrum using the transformed wavenumber and the original intensity;

[0016] S13: Demodulate the signal of the mapped spectrum using the spectral demodulation method to determine the physical length of the interference cavity;

[0017] S14: Solve the dispersion compensation function based on the mapped spectrum and the physical length of the interference cavity.

[0018] According to the present invention, a fiber optic Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation of interferometric spectra is provided, wherein the specific temperature environment requires that the refractive index data be known within the spectral observation wavenumber range.

[0019] According to the present invention, a fiber optic Fabry-Perot temperature demodulation method based on interferometric spectral frequency domain dispersion compensation is provided, wherein the spectral demodulation method includes:

[0020] S131: Perform Fourier spectrum analysis on the interference spectrum signal, find the peak on the amplitude spectrum, and use the peak position as the rough optical path difference of the interference cavity;

[0021] S132: Bandpass filtering is applied to the position of the interference cavity in the Fourier spectrum signal, and inverse Fourier transform is performed to obtain the interference fringes of a single interference cavity.

[0022] S133: Calculate the coarse fringe order of the filtered interference fringes by dividing the coarse optical path difference by the peak wavelength of the filtered interference fringes;

[0023] S134: Round the coarse fringe order to obtain the precise fringe order, and multiply it by the peak wavelength to obtain the physical length of the interference cavity.

[0024] According to the present invention, a fiber Fabry-Perot temperature demodulation method based on interferometric spectral frequency domain dispersion compensation is provided, wherein the numerical solution includes:

[0025] S141: Calculate the length of the interference cavity at all temperature points within the solution range based on the linear expansion formula;

[0026] S142: Using known refractive index data at different temperatures, fit the coefficients and interpolate the refractive index data at all temperature points within the solution range according to the thermo-optical effect formula;

[0027] S143: Using the refractive index data at all temperature points within the solution range, and according to the three Sellmeier formulas, fit the coefficients and interpolate the refractive index data at all wavenumbers within the spectral observation wavenumber range.

[0028] S144: Based on the numerical solution of the equations, calculate the peak position of the Fabry-Perot interferometer cavity in the Fourier frequency domain amplitude spectrum at all temperature points within the solution range with and without dispersion effect, thereby obtaining the numerical result of the dispersion compensation function.

[0029] According to the present invention, a fiber optic Fabry-Perot temperature demodulation method based on interferometric spectral frequency domain dispersion compensation is provided, wherein the numerical solution set of equations is as follows:

[0030]

[0031]

[0032] in, The position of the peak of the Fabry-Perot interferometer in the Fourier frequency domain amplitude spectrum when there is no dispersion effect; The position of the peak of the Fabry-Perot interferometer in the Fourier frequency domain amplitude spectrum when there is a dispersive effect; For materials at characteristic light wavenumbers The refractive index at that point; The characteristic light wave value, For the physical length variable of the Fabry-Perot interferometer cavity, The refractive index of a material with respect to the wavenumber of light The derivative value at that point, Wavelength, The refractive index is the material's refractive index.

[0033] According to the present invention, a fiber Fabry-Perot temperature demodulation method based on interferometric spectral frequency domain dispersion compensation is provided, wherein the dispersion compensation function follows a compensation model:

[0034]

[0035] in, The first fitting coefficient, The second fitting coefficient, The third fitting coefficient, The fourth fitting coefficient.

[0036] According to the present invention, a fiber Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation of interferometric spectrum is provided, wherein step S6 includes: taking characteristic wavenumbers. The two nearest peaks are designated as the first peak. Second peak The wrapped phase value at the characteristic wavenumber is calculated according to the phase formula. :

[0037] .

[0038] According to the present invention, a fiber Fabry-Perot temperature demodulation method based on interferometric spectral frequency domain dispersion compensation is provided, step S6 including: according to and Calculate the rough order of interference fringes The formula is:

[0039]

[0040] in, This represents the initial phase of the interference fringes on the sensor.

[0041] According to the present invention, a fiber Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation of interferometric spectrum is provided, wherein step S7 includes: ... Rounding is performed to obtain the precise fringe order. Calculate the characteristic wavenumber Precise optical path difference at the location The formula is:

[0042] .

[0043] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0044] This invention provides a fiber optic Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation in interferometric spectroscopy. By establishing a dispersion compensation model and solving for the compensation curve, this invention introduces dispersion compensation into a dispersion-free spectral demodulation method. This overcomes the problem of phase jumps in fiber optic Fabry-Perot temperature measurement demodulation results over a wide temperature range caused by dispersion effects in traditional spectral demodulation methods. The demodulation results of this invention are completely consistent with those of traditional methods in the non-phase-jump portion. Traditional methods exhibit phase jumps every 60 to 80°C, a problem not present in this method. This invention overcomes the phase jump problem caused by dispersion effects, providing a highly competitive technical solution for fiber optic Fabry-Perot temperature sensing demodulation.

[0045] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0047] Figure 1 This is a schematic flowchart of an optical fiber Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation of interference spectrum provided by the present invention.

[0048] Figure 2 This is a diagram showing the shift in the peak position of the Fabry-Perot cavity interference signal caused by the dispersion effect, provided by the present invention.

[0049] Figure 3 This is a typical dispersion compensation curve in an embodiment of the present invention.

[0050] Figure 4 This is a residual distribution diagram of the compensation curve of a Fabry temperature sensor according to an embodiment of the present invention under linear fitting and fitting with the formula described in the present invention.

[0051] Figure 5 This is a comparison chart of the demodulation results of the measurement results of three fiber optic Fabry-Perot temperature sensors in an embodiment of the present invention, with and without dispersion compensation.

[0052] Figure 6 This is a diagram of the interference spectral signal acquisition and demodulation system according to an embodiment of the present invention.

[0053] Figure label:

[0054] 1. SLD light source; 2. Single-mode optical fiber; 3. Fiber optic coupler; 4. Fiber optic Fabry-Perot temperature sensor; 5. Temperature chamber; 6. Spectrometer; 7. Spectrometer-host computer transmission line; 8. Host computer; 9. Host computer-temperature chamber control line. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention but cannot be used to limit the scope of this invention.

[0056] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0057] The following is combined with Figures 1 to 6 This invention is described.

[0058] like Figure 1 As shown, Figure 1 This is a schematic flowchart illustrating a fiber optic Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation using interferometric spectroscopy, provided by the present invention. It includes the following steps:

[0059] S1: Establish a dispersion simulation model and numerically solve the dispersion compensation function;

[0060] S2: Acquire the interference spectrum signal of the fiber optic Fabry-Perot temperature sensor under test, and perform Fourier spectrum analysis to obtain the Fourier frequency domain signal amplitude spectrum;

[0061] S3: Extract the peak of the amplitude spectrum of the Fourier frequency domain signal to obtain the value of the dispersive interference cavity;

[0062] S4: Calculate the value of the dispersion-free state after compensation based on the dispersion compensation function and the value of the dispersive interference cavity;

[0063] S5: Based on the value of the non-dispersion signal after compensation and the amplitude spectrum of the Fourier frequency domain signal, bandpass filtering and inverse Fourier transform are performed to obtain the interference fringes of a single interference cavity.

[0064] S6: Calculate the enclosed phase and coarse interference fringe order of the single interference cavity;

[0065] S7: The precise fringe order is calculated from the coarse interference fringe order, and the precise optical path difference is calculated from the precise fringe order and the enclosed phase.

[0066] based on Figure 2 The principle that dispersion effects cause a shift in the peak position of the Fabry-Perot cavity interference signal means that the demodulation results are affected by the dispersion effect of the cavity material, leading to phase jumps in measurement and demodulation over a wide temperature range. Dispersion compensation is necessary to eliminate the influence of dispersion effects. Figure 2 (a) and Figure 2 In (b), the vertical axis represents the intensity in arbitrary units, and it is clear that dispersion has a significant impact on measurement demodulation.

[0067] Specifically, based on Figure 2 The principle that dispersion effects cause the peak position of the Fabry-Perot cavity interference signal to shift leads to demodulation results that are affected by the dispersion effect of the cavity material, resulting in phase jumps during measurement and demodulation over a wide temperature range. To eliminate the influence of dispersion effects, dispersion compensation is necessary. The process involves placing the fiber optic Fabry-Perot temperature sensor under test in a specific temperature environment; acquiring the interference spectrum signal at that specific temperature; performing a mapping transformation on the wavenumber of the interference spectrum signal; constructing a new mapped spectrum using the transformed wavenumber and the original intensity; demodulating this mapped spectrum signal using spectral demodulation to determine the physical length of the interference cavity; and numerically solving the dispersion compensation curve based on a dispersion simulation model. In this embodiment, the Fabry-Perot cavity is made of silicon, and the initial cavity length is... The dispersion compensation mapping curves obtained using the above method for obtaining dispersion compensation curves within the temperature range of -100 to 200℃ are as follows: Figure 3 As shown. Among them, Figure 3 The horizontal axis represents the actual OPD (optical path difference), and the vertical axis represents the OPD after dispersion modulation.

[0068] Specifically, step S1 includes:

[0069] S11: Place the fiber optic Fabry-Perot temperature sensor under test in a specific temperature environment and collect the interference spectrum signal; the specific temperature environment requires that the refractive index data be known within the spectral observation wavenumber range.

[0070] S12: Perform a mapping transformation on the wavenumber of the interference spectrum signal, and construct the mapped spectrum using the transformed wavenumber and the original intensity;

[0071] S13: Demodulate the signal of the mapped spectrum using the spectral demodulation method to determine the physical length of the interference cavity;

[0072] S14: Solve the dispersion compensation curve based on the mapped spectrum and the physical length of the interference cavity.

[0073] Specifically, the spectral demodulation method includes:

[0074] S131: Perform Fourier spectrum analysis on the interference spectrum signal, find the peak on the amplitude spectrum, and use the peak position as the rough optical path difference of the interference cavity;

[0075] S132: Bandpass filtering is applied to the position of the interference cavity in the Fourier spectrum signal, and inverse Fourier transform is performed to obtain the interference fringes of a single interference cavity.

[0076] S133: Calculate the coarse fringe order of the filtered interference fringes by dividing the coarse optical path difference by the peak wavelength of the filtered interference fringes;

[0077] S134: Round the coarse fringe order to obtain the precise fringe order, and multiply it by the peak wavelength to obtain the physical length of the interference cavity.

[0078] Specifically, the numerical solution includes:

[0079] S141: According to the linear expansion formula The length of the interference cavity at all temperature points within the solution range is calculated. For the physical length variable of the Fabry-Perot interferometer cavity, is a function of the linear expansion coefficient of the material. For temperature variables, For a specific temperature value, This represents the physical length of the Fabry-Perot interferometer cavity under specific temperature conditions.

[0080] S142: Using known refractive index data at different temperatures, based on the thermo-optical effect formula... The fitting coefficients are then used to interpolate the refractive index data for all temperature points within the solution range. Among these, The refractive index is a function of temperature. Thermo-optical effect constant, The first coefficient of the thermo-optical effect, The second coefficient of the thermo-optical effect, The first temperature coefficient of the thermo-optical effect. The second temperature coefficient of the thermo-optic effect.

[0081] S143: Using refractive index data at all temperature points within the solution range, and based on the three Sellmeier formulas, fit the coefficients and interpolate the refractive index data at all wavenumbers within the spectral observation wavenumber range. The three Sellmeier formulas are:

[0082]

[0083] in, For light wavenumber The square of the refractive index, As the first parameter, For the second parameter, As the third parameter, The fourth parameter, The fifth parameter, This is the sixth parameter.

[0084] S144: Based on the numerical solution of the equation set, calculate the peak position of the Fabry interferometer cavity in the Fourier frequency domain amplitude spectrum with and without dispersion effect at all temperature points within the solution range, and thus obtain the numerical result of the dispersion compensation curve.

[0085] The numerical solution system of equations is as follows:

[0086]

[0087]

[0088] in, The position of the peak of the Fabry-Perot interferometer in the Fourier frequency domain amplitude spectrum when there is no dispersion effect; The position of the peak of the Fabry-Perot interferometer in the Fourier frequency domain amplitude spectrum when there is a dispersive effect; For materials at characteristic light wavenumbers The refractive index at that point; The characteristic light wave value, For the physical length variable of the Fabry-Perot interferometer cavity, The refractive index of a material with respect to the wavenumber of light The derivative value at that point, Wavelength, The refractive index is the material's refractive index.

[0089] Specifically, the dispersion compensation curve follows a compensation model:

[0090]

[0091] in, The first fitting coefficient, The second fitting coefficient, The third fitting coefficient, The fourth fitting coefficient.

[0092] First, the dispersion compensation curve Linear fitting was performed on the numerical results, and the fitting results are as follows: Figure 4 As shown in (a), the fitted curve is The maximum fitting error reached 31.6 μm at this point. To further improve the accuracy of the fitting model, observation revealed that the residual distribution approximates the distribution model of a checkmark function. Therefore, a checkmark function term was introduced into the linear fitting formula, and this residual compensation term was substituted into the linear fitting formula. By combining like terms, the empirical fitting model formula described in this invention was obtained. This empirical fitting model was then used to refit the compensation curve. The numerical results were fitted, and the fitting results are as follows: Figure 4 As shown in (b), the fitted curve is:

[0093] .

[0094] Furthermore, to verify the applicability of the fitting model, numerical simulations and fitting analyses were performed on germanium cavity and zinc sulfide cavity Fabry-Perot sensors under the same interferometric cavity physical length, light source bandwidth, and wavelength conditions. The compensation curve for the germanium cavity is as follows: The compensation curve for the zinc sulfide cavity is as follows: In the fitting residual results, the maximum residual for the silicon cavity is 7.46 nm, the maximum residual for the germanium cavity is 10.06 nm, and the maximum residual for the zinc sulfide cavity is 14.02 nm. These maximum residuals are all less than half a characteristic wavelength and will not cause the demodulation method to fail due to a jump, thus demonstrating the applicability of the fitting model.

[0095] Specifically, step S5 includes: taking the characteristic wavenumber. The two nearest peaks are designated as the first peak. Second peak The wrapped phase value at the characteristic wavenumber is calculated according to the phase formula. :

[0096] .

[0097] Specifically, step S6 includes: according to and Calculate the rough order of interference fringes The formula is:

[0098]

[0099] in, This represents the initial phase of the interference fringes on the sensor.

[0100] Specifically, step S7 includes: […]. Rounding is performed to obtain the precise fringe order. Calculate the characteristic wavenumber Precise optical path difference at the location The formula is:

[0101] .

[0102] like Figure 5 As shown, Figure 5 (a) Figure 5 (b) and Figure 5 As shown in (c), the demodulation results of the method of the present invention are compared with those of the dispersion-free compensation method. Temperature tests ranging from -40℃ to 100℃ were conducted using three sensors, and the spectra of the three sensors were collected and demodulated. The results show that after eliminating the influence of dispersion effects on sensor temperature measurement, the results obtained by the present method are completely consistent with those of the traditional method in the non-phase-jump part. The traditional method results in phase jumps every 60 to 80℃, while this method does not have this problem. Experiments demonstrate that the method of the present invention has the ability to overcome the phase jump problem caused by the dispersion effect of the Fabry-Perot cavity material.

[0103] Figure 6 The diagram shows an interferometric spectral signal acquisition and demodulation system according to an embodiment of the present invention, including: SLD light source 1, single-mode optical fiber 2, optical fiber coupler 3, optical fiber Fabry-Perot temperature sensor 4, temperature chamber 5, spectrometer 6, spectrometer-host computer transmission line 7, host computer 8, and host computer-temperature chamber control line 9.

[0104] In this system, the broadband light emitted by the SLD light source 1 is transmitted via single-mode fiber 2, through fiber optic coupler 3, and then enters the fiber optic Fabry-Perot temperature sensor 4. The sensor is placed in a temperature chamber 5. The sensor's sensitive diaphragm deforms with changes in the external temperature, causing a change in the length of the Fabry-Perot cavity. The light signal modulated by the Fabry-Perot sensor returns to the fiber optic coupler 3, passes through the single-mode fiber, and enters the spectrometer 6. The spectrometer collects interference signals containing temperature information and transmits them to the host computer 8 for demodulation via the spectrometer-host computer transmission line 7. At the same time, the host computer can control the temperature of the temperature chamber via the host computer-temperature chamber control line 9 to provide different external temperatures for the sensor.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0106] It should be noted that the embodiments of this disclosure can be implemented using hardware, software, or a combination of both. The hardware portion can be implemented using dedicated logic; the software portion can be stored in memory and executed by a suitable instruction execution system, such as a microprocessor or dedicated-design hardware. Those skilled in the art will understand that the above-described devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code provided on a programmable memory or a data carrier such as an optical or electronic signal carrier.

[0107] Furthermore, although the operation of the methods of this disclosure is described in a specific order in the accompanying drawings, this does not require or imply that these operations must be performed in that specific order, or that all the operations shown must be performed to achieve the desired result. Rather, the steps depicted in the flowcharts may be performed in a different order. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps. It should also be noted that the features and functions of two or more devices according to this disclosure may be embodied in one device. Conversely, the features and functions of one device described above may be further divided and embodied by multiple devices.

[0108] While this disclosure has been described with reference to several specific embodiments, it should be understood that this disclosure is not limited to the specific embodiments disclosed. This disclosure is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A fiber optic Fabry-Perot temperature demodulation method based on interferometric spectral frequency domain dispersion compensation, characterized in that, Includes the following steps: S1: Establish a dispersion simulation model and numerically solve the dispersion compensation function; S2: Acquire the interference spectrum signal of the fiber optic Fabry-Perot temperature sensor under test, and perform Fourier spectrum analysis to obtain the Fourier frequency domain signal amplitude spectrum; S3: Extract the peak of the amplitude spectrum of the Fourier frequency domain signal to obtain the value of the dispersive interference cavity; S4: Calculate the value of the dispersion-free state after compensation based on the dispersion compensation function and the value of the dispersive interference cavity; S5: Based on the value of the non-dispersion signal after compensation and the amplitude spectrum of the Fourier frequency domain signal, bandpass filtering and inverse Fourier transform are performed to obtain the interference fringes of a single interference cavity. S6: Calculate the enclosed phase and coarse interference fringe order of the single interference cavity; S7: The precise fringe order is calculated from the coarse interference fringe order, and the precise optical path difference is calculated from the precise fringe order and the enclosed phase.

2. The fiber Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation of interferometric spectrum according to claim 1, characterized in that, Step S1 includes: S11: Place the fiber optic Fabry-Perot temperature sensor under test in a temperature environment and collect the interference spectrum signal; S12: Perform a mapping transformation on the wavenumber of the interference spectrum signal, and construct the mapped spectrum using the transformed wavenumber and the original intensity; S13: Demodulate the signal of the mapped spectrum using the spectral demodulation method to determine the physical length of the interference cavity; S14: Solve the dispersion compensation function based on the mapped spectrum and the physical length of the interference cavity.

3. The fiber Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation of interferometric spectra according to claim 2, characterized in that, The required temperature environment necessitates that the refractive index data be known within the spectral observation wavenumber range.

4. The fiber Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation of interferometric spectrum according to claim 2, characterized in that, The spectral demodulation method includes: S131: Perform Fourier spectrum analysis on the interference spectrum signal, find the peak on the amplitude spectrum, and use the peak position as the rough optical path difference of the interference cavity; S132: Bandpass filtering is applied to the position of the interference cavity in the Fourier spectrum signal, and inverse Fourier transform is performed to obtain the interference fringes of a single interference cavity. S133: Calculate the coarse fringe order of the filtered interference fringes by dividing the coarse optical path difference by the peak wavelength of the filtered interference fringes; S134: Round the coarse fringe order to obtain the precise fringe order, and multiply it by the peak wavelength to obtain the physical length of the interference cavity.

5. The fiber Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation of interferometric spectrum according to claim 4, characterized in that, The numerical solution includes: S141: Calculate the length of the interference cavity at all temperature points within the solution range based on the linear expansion formula; S142: Using known refractive index data at different temperatures, fit the coefficients and interpolate the refractive index data at all temperature points within the solution range according to the thermo-optical effect formula; S143: Using the refractive index data at all temperature points within the solution range, and according to the three Sellmeier formulas, fit the coefficients and interpolate the refractive index data at all wavenumbers within the spectral observation wavenumber range. S144: Based on the numerical solution of the equations, calculate the peak position of the Fabry-Perot interferometer cavity in the Fourier frequency domain amplitude spectrum at all temperature points within the solution range with and without dispersion effect, thereby obtaining the numerical result of the dispersion compensation function.

6. The fiber Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation of interferometric spectrum according to claim 5, characterized in that, The numerical solution system of equations is as follows: in, The position of the peak of the Fabry-Perot interferometer in the Fourier frequency domain amplitude spectrum when there is no dispersion effect; The position of the peak of the Fabry-Perot interferometer in the Fourier frequency domain amplitude spectrum when there is a dispersive effect; For materials at characteristic light wavenumbers The refractive index at that point; The characteristic light wave value, For the physical length variable of the Fabry-Perot interferometer cavity, The refractive index of a material with respect to the wavenumber of light The derivative value at that point, Wavelength, The refractive index is the material's refractive index.

7. The fiber Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation of interferometric spectrum according to claim 6, characterized in that, The dispersion compensation function follows a compensation model: in, The first fitting coefficient, The second fitting coefficient, The third fitting coefficient, The fourth fitting coefficient.

8. The fiber optic Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation of interferometric spectra according to claim 6, characterized in that, Step S6 includes: taking the two nearest peaks near the characteristic wavenumber of the interference fringes, and recording them as the first peak. Second peak The wrapped phase value at the characteristic wavenumber is calculated according to the phase formula. : 。 9. The fiber optic Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation of interferometric spectra according to claim 8, characterized in that, Step S6 also includes: according to and Calculate the rough order of interference fringes The formula is: in, This represents the initial phase of the interference fringes on the sensor.

10. The fiber Fabry-Perot temperature demodulation method based on frequency domain dispersion compensation of interferometric spectrum according to claim 9, characterized in that, Step S7 includes: ... Rounding is performed to obtain the precise fringe order. The precise optical path difference at the characteristic wavenumber was calculated. The formula is: 。

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