CN107037583B

CN107037583B - Method, device and system for demodulating center wavelength and phase shift of phase shift grating

Info

Publication number: CN107037583B
Application number: CN201710356343.5A
Authority: CN
Inventors: 王义平; 何俊; 许金山
Original assignee: Shenzhen Photon Sensing Technology Co ltd
Current assignee: Shenzhen Photon Sensing Technology Co ltd
Priority date: 2017-05-19
Filing date: 2017-05-19
Publication date: 2023-08-08
Anticipated expiration: 2037-05-19
Also published as: CN107037583A

Abstract

The invention belongs to the field of optical fiber sensing, and particularly relates to a method, a device and a system for demodulating the center wavelength and the phase shift of a phase shift grating. The method or the device for simultaneously demodulating the center wavelength and the phase shift quantity of the phase shift grating provided by the invention calculates by utilizing the reflection spectrum data of the phase shift grating to be demodulated so as to obtain the center wavelength and the phase shift quantity of the phase shift grating to be demodulated, thereby solving the problem that the center wavelength and the phase shift quantity of the phase shift grating cannot be effectively demodulated, and further utilizing the response difference of the center wavelength and the phase shift quantity to the external physical quantity change to carry out sensing application.

Description

Method, device and system for demodulating center wavelength and phase shift of phase shift grating

Technical Field

The invention belongs to the field of optical fiber sensing, and particularly relates to a method, a device and a system for demodulating the center wavelength and the phase shift of a phase shift grating.

Background

The phase shift fiber grating is a non-uniform fiber grating, and is a special grating formed by introducing phase mutation in the axial refractive index modulation of the uniform grating. In recent years, phase shift fiber gratings have been widely studied and used in the fields of narrow band filters, fiber lasers, fiber sensors, and the like. The prior researches only analyze the influence of the magnitude and the position of the phase shift on the grating reflection spectrum, but the center wavelength and the magnitude of the phase shift are reversely deduced from the grating reflection spectrum without further researches.

One or more transmission windows with extremely narrow linewidth appear in the reflection spectrum of the phase-shift fiber grating, and the center wavelength of the phase-shift grating and the phase-shift amount of the phase-shift grating cannot be intuitively obtained due to the existence of the narrow-band transmission window. Therefore, the current method cannot effectively demodulate the center wavelength and the amount of phase shift of the demodulation phase shift optical fiber.

Disclosure of Invention

The invention provides a method, a device and a system for demodulating the center wavelength and the phase shift amount of a phase shift grating, and aims to solve the problem that the center wavelength and the phase shift amount of the phase shift grating cannot be effectively demodulated.

In order to solve the technical problems, the invention provides a method for demodulating the center wavelength and the phase shift of a phase shift grating, which comprises the following steps:

step A: calculating reflection spectrum data of the phase shift grating to be demodulated by using a peak searching algorithm to obtain peak wavelengths of reflection peaks in the reflection spectrum data of the phase shift grating to be demodulated;

and (B) step (B): calculating the peak value wavelength of each reflection peak in the reflection spectrum data of the phase shift grating to be demodulated by using a comparison algorithm to obtain the wavelength corresponding to the minimum value of the reflectivity of the narrow-band transmission peak between the maximum peak value wavelength of the reflectivity and the sub-maximum peak value wavelength of the reflectivity in the reflection spectrum data of the phase shift grating to be demodulated;

Step C: removing spectral data of a narrow-band transmission peak between the maximum peak-to-peak wavelength and the sub-maximum peak-to-peak wavelength of the reflectivity from the reflection spectral data of the phase shift grating to be demodulated by utilizing a clipping algorithm to obtain the reflection spectral data of the phase shift grating to be demodulated after clipping;

step D: performing data fitting on the reflection spectrum data of the phase shift grating to be demodulated after the cutting by using a data fitting algorithm to obtain a value of a preset parameter;

step E: respectively bringing the values of the preset parameters into a preset center wavelength calculation formula and a preset 3dB bandwidth calculation formula to calculate so as to obtain the center wavelength and the 3dB bandwidth of the phase shift grating to be demodulated;

step F: and carrying out phase shift analysis on the basis of the wavelength corresponding to the minimum reflectivity value of the narrow-band transmission peak, the center wavelength of the phase shift grating to be demodulated and the 3dB bandwidth to obtain the phase shift of the phase shift grating to be demodulated.

Further, when the data fitting algorithm in the step D adopts a quadratic function fitting algorithm, the step E further includes:

if the reflectivity maximum peak-to-peak wavelength lambdaa is larger than the reflectivity sub-maximum peak-to-peak wavelength lambdab in the reflection spectrum data of the phase shift grating to be demodulated after the cutting, searching the corresponding wavelength lambdax of the first reflectivity minimum point leftwards in the reflection spectrum by the reflectivity sub-maximum peak-to-peak wavelength lambdab, and searching the corresponding wavelength lambday of the first reflectivity minimum point rightwards in the reflection spectrum by the reflectivity maximum peak-to-peak wavelength lambdaa;

If the reflectivity maximum peak-to-peak wavelength lambdaa is smaller than the reflectivity sub-maximum peak-to-peak wavelength lambdab in the reflection spectrum data of the phase shift grating to be demodulated after the cutting, searching the corresponding wavelength lambdax of the first reflectivity minimum point leftwards in the reflection spectrum by the reflectivity maximum peak-to-peak wavelength lambdaa, and searching the corresponding wavelength lambday of the first reflectivity minimum point rightwards in the reflection spectrum by the reflectivity sub-maximum peak-to-peak wavelength lambdab;

and removing spectral data with a wavelength value smaller than lambdax in the reflection spectrum data of the cut phase shift grating to be demodulated, removing spectral data with a wavelength value larger than lambday in the reflection spectrum data of the cut phase shift grating to be demodulated, and taking the rest spectral data as the reflection spectrum data of the optimized cut phase shift grating to be demodulated.

Further, if the data fitting algorithm is a quadratic function fitting algorithm, the step D specifically includes:

performing data fitting on the reflection spectrum data of the phase shift grating to be demodulated after optimization and cutting by using the quadratic function fitting algorithm to obtain a quadratic term coefficient a, a primary term coefficient b and a constant term c;

or ；

if the data fitting algorithm is a gaussian function fitting algorithm, after the step C, the step D specifically includes:

Performing data fitting on the reflection spectrum data of the phase shift grating to be demodulated after the cutting by using the Gaussian function fitting algorithm to obtain an equation coefficient B, and a position parameter mu and a distribution discrete degree description parameter sigma of a mapping curve between the wavelength and the reflectivity generated by fitting

Further, if the quadratic function fitting algorithm is adopted in the step D, the step E specifically includes:

the quadratic term coefficient a, the first term coefficient b and the constant term c are respectively put into the first center wavelength calculation formula and the first 3dB bandwidth calculation formula to be calculated, so that the center wavelength lambdad and the 3dB bandwidth delta lambda of the phase shift grating to be demodulated are obtained; wherein the first center wavelength calculation formula is expressed as:

λ _d ＝-b/2a；

the first 3dB bandwidth calculation formula is expressed as:

or ；

if the gaussian fitting algorithm is adopted in the step D, the step E specifically includes:

the equation coefficient B, the position parameter mu and the distribution discrete degree description parameter sigma of the mapping curve between the wavelength and the reflectivity generated by fitting are respectively brought into the second center wavelength calculation formula and the second 3dB bandwidth calculation formula to be calculated, so that the center wavelength lambdad and the 3dB bandwidth delta lambda of the phase shift grating to be demodulated are obtained; wherein the second center wavelength calculation formula is expressed as:

λ _d ＝μ

The second 3dB bandwidth calculation formula is expressed as:

further, in the step F, the phase shift amount calculation formula of the phase shift grating to be demodulated is as follows:

wherein ,and (3) representing the phase shift quantity of the phase shift grating to be demodulated, wherein k represents the phase shift sensitivity, C represents an equation constant term, λc represents the wavelength corresponding to the minimum reflectivity value of the narrow-band transmission peak, λd represents the center wavelength of the phase shift grating to be demodulated, and Δλ represents the 3dB bandwidth.

The invention also provides a data processing device for demodulating the center wavelength and the phase shift amount of the phase shift grating, which comprises:

the peak searching algorithm module is used for calculating the reflection spectrum data of the phase shift grating to be demodulated by utilizing a peak searching algorithm to obtain the peak wavelength of each reflection peak in the reflection spectrum data of the phase shift grating to be demodulated;

the comparison algorithm module is used for calculating the peak value wavelength of each reflection peak in the reflection spectrum data of the phase shift grating to be demodulated by utilizing a comparison algorithm to obtain the wavelength corresponding to the minimum value of the reflectivity of the narrow-band transmission peak between the maximum peak value wavelength of the reflectivity and the sub-maximum peak value wavelength of the reflectivity in the reflection spectrum of the phase shift grating to be demodulated;

the clipping algorithm module is used for removing the spectral data of the narrow-band transmission peak between the maximum reflectivity peak value wavelength and the next maximum reflectivity peak value wavelength in the reflection spectrum data of the phase shift grating to be demodulated by using a clipping algorithm so as to obtain the reflection spectrum data of the phase shift grating to be demodulated after clipping;

The data fitting module is used for carrying out data fitting on the reflection spectrum data of the phase shift grating to be demodulated after the cutting by utilizing a data fitting algorithm so as to obtain a value of a preset parameter;

the data analysis module is used for respectively bringing the values of the preset parameters into a preset center wavelength calculation formula and a preset 3dB bandwidth calculation formula to calculate so as to obtain the center wavelength and the 3dB bandwidth of the phase shift grating to be demodulated;

and the phase shift amount analysis module is used for carrying out phase shift amount analysis on the basis of the wavelength corresponding to the minimum reflectivity value of the narrow-band transmission peak, the center wavelength of the phase shift grating to be demodulated and the 3dB bandwidth so as to obtain the phase shift amount of the phase shift grating to be demodulated.

Further, when the data fitting algorithm adopts a quadratic function fitting algorithm in the data fitting module, the clipping algorithm module is specifically configured to:

if the maximum peak-to-peak wavelength λa of the reflectivity in the reflection spectrum of the phase shift grating to be demodulated is larger than the sub-maximum peak-to-peak wavelength λb of the reflectivity, searching the corresponding wavelength λx of the first minimum point of reflectivity leftwards in the reflection spectrum by the sub-maximum peak-to-peak wavelength λb of the reflectivity, and searching the corresponding wavelength λy of the first minimum point of reflectivity rightwards in the reflection spectrum by the maximum peak-to-peak wavelength λa of the reflectivity;

If the maximum peak-to-peak wavelength λa of the reflectivity in the reflection spectrum of the phase shift grating to be demodulated is smaller than the sub-maximum peak-to-peak wavelength λb of the reflectivity, searching the corresponding wavelength λx of the first minimum point of reflectivity leftwards in the reflection spectrum by the maximum peak-to-peak wavelength λa of the reflectivity, and searching the corresponding wavelength λy of the first minimum point of reflectivity rightwards in the reflection spectrum by the sub-maximum peak-to-peak wavelength λb of the reflectivity;

removing spectral data with a wavelength value smaller than lambdax in the reflection spectrum of the phase shift grating to be demodulated, removing spectral data with a wavelength value larger than lambday in the reflection spectrum of the phase shift grating to be demodulated, and taking the rest spectral data as the reflection spectrum data of the phase shift grating to be demodulated after the cutting.

The invention also provides a system for demodulating the center wavelength and the phase shift amount of the phase shift grating, which comprises the data processing device; the system also comprises a light source unit, a phase shift grating unit, an optical coupling unit and a spectrum acquisition unit;

an output port of the light source unit is connected with a first port of the optical coupling unit;

the input port of the phase shift grating unit is connected with the second port of the optical coupling unit;

The third port of the optical coupling unit is connected with the input port of the spectrum acquisition unit;

the output port of the spectrum acquisition unit is connected with the input port of the data processing device;

the light source unit is used for emitting illumination light, and the illumination light is transmitted to the optical coupling unit;

the optical coupling unit is used for transmitting the irradiation light to the phase shift grating unit;

the phase shift grating unit is used for reflecting the irradiation light to form a reflection spectrum of the phase shift grating to be demodulated, and the reflection spectrum of the phase shift grating to be demodulated is transmitted to the optical coupling unit;

the optical coupling unit is further used for transmitting the reflection spectrum of the phase shift grating to be demodulated to the spectrum acquisition unit;

the spectrum acquisition unit is used for acquiring reflection spectrum data of the phase shift grating to be demodulated, and the reflection spectrum data are transmitted to the data processing device;

the data processing device is used for calculating by utilizing the reflection spectrum data of the phase shift grating to be demodulated so as to obtain the center wavelength and the phase shift quantity of the phase shift grating to be demodulated.

Further, the data processing device is further configured to transmit the obtained center wavelength and 3dB bandwidth of the phase shift grating to be demodulated to the spectrum acquisition unit;

The spectrum acquisition unit is further used for determining the wavelength range and the data acquisition precision of data acquisition by utilizing the center wavelength and the 3dB bandwidth of the phase shift grating to be demodulated.

Further, the data processing device is any one of an intelligent terminal, a DSP chip, an FPGA chip or a singlechip which is provided with data processing software.

Compared with the prior art, the invention has the beneficial effects that:

the method for simultaneously demodulating the center wavelength and the phase shift quantity of the phase shift grating provided by the invention utilizes the reflection spectrum data of the phase shift grating to be demodulated to calculate so as to obtain the center wavelength and the phase shift quantity of the phase shift grating to be demodulated, thereby solving the problem that the center wavelength and the phase shift quantity of the phase shift grating cannot be effectively demodulated, and further utilizing the response difference of the center wavelength and the phase shift quantity to the external physical quantity change to carry out sensing application.

Drawings

FIG. 1 is a flow chart of a method for demodulating the center wavelength and the phase shift of a phase shift grating simultaneously according to a first embodiment of the present invention;

FIG. 2 is a schematic diagram of a data processing apparatus for simultaneously demodulating the center wavelength and the phase shift of a phase shift grating according to a third embodiment of the present invention;

FIG. 3 is a schematic diagram of a data processing apparatus for simultaneously demodulating the center wavelength and the phase shift of a phase shift grating according to a fourth embodiment of the present invention;

FIG. 4 is a schematic diagram of a system for simultaneously demodulating the center wavelength and the phase shift of a phase shift grating according to a fifth embodiment of the present invention;

FIG. 5 is a schematic diagram of a system for simultaneously demodulating the center wavelength and the phase shift of a phase shift grating according to a sixth embodiment of the present invention;

FIG. 6 is a schematic diagram of a system for simultaneously demodulating the center wavelength and the phase shift of a phase shift grating according to a seventh embodiment of the present invention;

FIG. 7 is an original reflection spectrum of a phase shift grating in a phase shift grating demodulation process according to a seventh embodiment of the present invention;

FIG. 8 is a reflection spectrum of a phase shift grating after clipping during demodulation of the phase shift grating according to a seventh embodiment of the present invention;

FIG. 9 is an image of a data fitting equation during phase shift grating demodulation according to a seventh embodiment of the present invention;

FIG. 10 is a reflection spectrum of a phase shift grating obtained by numerical simulation during demodulation of the phase shift grating according to an eighth embodiment of the present invention;

FIG. 11 is a reflection spectrum of a phase shift grating after clipping during demodulation of the phase shift grating according to an eighth embodiment of the present invention;

fig. 12 is an image of a data fitting equation during phase shift grating demodulation according to an eighth embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

As a first embodiment of the present invention, as shown in fig. 1, the present invention provides a method for demodulating a center wavelength and a phase shift amount of a phase shift grating, which includes:

step S101: and calculating reflection spectrum data of the phase shift grating to be demodulated by using a peak searching algorithm to obtain peak wavelengths of reflection peaks in the reflection spectrum data of the phase shift grating to be demodulated.

Step S102: and calculating the peak value wavelength of each reflection peak in the reflection spectrum data of the phase shift grating to be demodulated by using a comparison algorithm to obtain the wavelength corresponding to the minimum value of the reflectivity of the narrow-band transmission peak between the maximum peak value wavelength of the reflectivity and the sub-maximum peak value wavelength of the reflectivity in the reflection spectrum data of the phase shift grating to be demodulated.

Step S103: and removing the spectral data of the narrow-band transmission peak between the maximum peak-to-peak wavelength and the sub-maximum peak-to-peak wavelength of the reflectivity from the reflection spectral data of the phase shift grating to be demodulated by utilizing a clipping algorithm to obtain the reflection spectral data of the phase shift grating to be demodulated after clipping.

Step S104: and performing data fitting on the reflection spectrum data of the phase shift grating to be demodulated after the cutting by using a data fitting algorithm to obtain the value of the preset parameter.

Step S105: and respectively carrying the values of the preset parameters into a preset center wavelength calculation formula and a preset 3dB bandwidth calculation formula to calculate so as to obtain the center wavelength and the 3dB bandwidth of the phase shift grating to be demodulated.

Step S106: and carrying out phase shift analysis on the basis of the wavelength corresponding to the minimum reflectivity value of the narrow-band transmission peak, the center wavelength of the phase shift grating to be demodulated and the 3dB bandwidth to obtain the phase shift of the phase shift grating to be demodulated.

In summary, according to the method provided by the first embodiment of the present invention, the reflection spectrum data of the phase shift grating to be demodulated is used to calculate to obtain the center wavelength and the phase shift amount of the phase shift grating to be demodulated, so that the problem that the center wavelength and the phase shift amount of the phase shift grating cannot be effectively demodulated is solved, and the response difference of the center wavelength and the phase shift amount to the external physical amount change can be used for sensing application.

As a second embodiment of the present invention, as shown in fig. 1, the present invention provides a method for demodulating a center wavelength and a phase shift amount of a phase shift grating, which includes:

Step S102: and calculating the peak value wavelength of each reflection peak in the reflection spectrum data of the phase shift grating to be demodulated by using a comparison algorithm to obtain the wavelength corresponding to the minimum value of the reflectivity of the narrow-band transmission peak between the maximum peak value wavelength of the reflectivity and the sub-maximum peak value wavelength of the reflectivity in the reflection spectrum data of the phase shift grating to be demodulated. In step S102, the comparison algorithm is any one of a bubbling ordering, a direct insertion ordering, or a selection ordering algorithm.

Step S103: and removing the spectral data of the narrow-band transmission peak between the maximum peak-to-peak wavelength and the sub-maximum peak-to-peak wavelength of the reflectivity from the reflection spectral data of the phase shift grating to be demodulated by utilizing a clipping algorithm to obtain the reflection spectral data of the phase shift grating to be demodulated after clipping. It should be noted that, when the data fitting algorithm adopted in the following step 104 is a quadratic function fitting algorithm, in this step S103, on the basis of obtaining the reflection spectrum data of the phase shift grating to be demodulated after being cut, further cutting operation is required to be performed on the reflection spectrum data of the phase shift grating to be demodulated after being cut, so as to obtain the reflection spectrum data of the phase shift grating to be demodulated after being cut. At this time, before step S104, the following steps are further included:

S103-1: if the reflectance maximum peak-to-peak wavelength λa is larger than the reflectance sub-maximum peak-to-peak wavelength λb in the reflectance spectrum data of the phase shift grating to be demodulated after the cutting, searching the corresponding wavelength λx of the first reflectance minimum point leftwards in the reflectance spectrum by the reflectance sub-maximum peak-to-peak wavelength λb, and searching the corresponding wavelength λy of the first reflectance minimum point rightwards in the reflectance spectrum by the reflectance maximum peak-to-peak wavelength λa;

or ,

s103-1: if the reflectance maximum peak-to-peak wavelength λa is smaller than the reflectance sub-maximum peak-to-peak wavelength λb in the reflectance spectrum data of the phase shift grating to be demodulated after the cutting, searching the corresponding wavelength λx of the first reflectance minimum point leftwards in the reflectance spectrum by the reflectance maximum peak-to-peak wavelength λa, and searching the corresponding wavelength λy of the first reflectance minimum point rightwards in the reflectance spectrum by the reflectance sub-maximum peak-to-peak wavelength λb.

S103-2: removing spectral data with a wavelength value smaller than lambdax in the reflection spectrum data of the cut phase shift grating to be demodulated, removing spectral data with a wavelength value larger than lambday in the reflection spectrum data of the cut phase shift grating to be demodulated, and taking the rest of spectral data as the reflection spectrum data of the optimized cut phase shift grating to be demodulated.

Step S104: and performing data fitting on the reflection spectrum data of the phase shift grating to be demodulated after the cutting by using a data fitting algorithm to obtain the value of the preset parameter. In step S104, the data fitting algorithm is any one of a quadratic function fitting algorithm and a gaussian function fitting algorithm. When the method is a Gaussian function fitting algorithm, carrying out data fitting on the reflection spectrum data of the phase shift grating to be demodulated after the cutting to obtain a value of a preset parameter; and when the method is a quadratic function fitting algorithm, performing data fitting on the reflection spectrum data of the phase shift grating to be demodulated after optimization and cutting to obtain the value of the preset parameter.

When the quadratic function fitting algorithm is adopted in step S104, step S104 specifically includes:

and carrying out data fitting on the reflection spectrum data of the phase shift grating to be demodulated after optimizing and cutting by using a quadratic function fitting algorithm so as to obtain a quadratic term coefficient a, a primary term coefficient b and a constant term c.

Further, after the quadratic coefficient a, the first quadratic coefficient b and the constant term c are obtained in step S104, a mapping formula (1) between the wavelength and the reflectivity may be further obtained as follows:

R＝aλ ² +bλ+c (1)

wherein R represents the reflectivity of the phase shift grating to be demodulated, lambda represents the wavelength, a represents the quadratic term coefficient, b represents the first order term coefficient, and c represents the constant term.

or ；

when the gaussian fitting algorithm is adopted in step S104, step S104 specifically includes:

and carrying out data fitting on the reflection spectrum data of the phase shift grating to be demodulated after the cutting by using a Gaussian function fitting algorithm to obtain a position parameter mu and a distribution discrete degree description parameter sigma of a mapping curve between the wavelength and the reflectivity generated by fitting, an equation coefficient A, an equation coefficient B and a constant term D.

Further, after the position parameter μ and the distribution dispersion degree description parameter σ of the mapping curve between the wavelength and the reflectance obtained in the fitting in step S104, the equation coefficient a, the equation coefficient B, and the constant term D, a mapping formula (2) between the wavelength and the reflectance may be further obtained as follows:

where R represents the reflectivity of the phase shift grating to be demodulated, λ represents the wavelength, μ represents the position parameter of the mapping curve between the wavelength and reflectivity generated by fitting (i.e., the position parameter of formula (2)), σ represents the distribution dispersion degree description parameter of the mapping curve between the wavelength and reflectivity generated by fitting (i.e., the distribution dispersion degree description parameter of formula (2)), A, B represents the equation coefficient, and D represents the constant term.

Step S105: and (3) respectively carrying the values of the preset parameters obtained in the step (S104) into a preset center wavelength calculation formula and a preset 3dB bandwidth calculation formula to calculate so as to obtain the center wavelength and the 3dB bandwidth of the phase shift grating to be demodulated.

It should be noted that, when the quadratic function fitting algorithm is adopted in step S104, the embodiment of the present invention further derives the first center wavelength calculation formula and the first 3dB bandwidth calculation formula by using the above-mentioned mapping formula (1) between the wavelength and the reflectivity. When the gaussian function fitting algorithm is adopted in step S104, the embodiment of the present invention further derives the second center wavelength calculation formula and the second 3dB bandwidth calculation formula by using the above-mentioned mapping formula (2) between the wavelength and the reflectivity.

When the quadratic function fitting algorithm is adopted in step S104, step S105 specifically includes:

the quadratic term coefficient a, the first term coefficient b and the constant term c are respectively brought into a first center wavelength calculation formula and a first 3dB bandwidth calculation formula to be calculated, so that the center wavelength lambdad and the 3dB bandwidth delta lambda of the phase shift grating to be demodulated are obtained; wherein, the first center wavelength calculation formula is expressed as:

λ _d ＝-b/2a；

the first 3dB bandwidth calculation formula is expressed as:

or ；

when the gaussian fitting algorithm is adopted in step S104, step S105 specifically includes:

the equation coefficient B, the position parameter mu and the distribution discrete degree description parameter sigma of the mapping curve between the wavelength and the reflectivity generated by fitting are respectively brought into a second center wavelength calculation formula and a second 3dB bandwidth calculation formula to be calculated, so that the center wavelength lambdad and the 3dB bandwidth delta lambda of the phase shift grating to be demodulated are obtained; wherein the second center wavelength calculation formula is expressed as:

λ _d ＝μ

The second 3dB bandwidth calculation formula is expressed as:

step S106: and carrying out phase shift analysis on the basis of the wavelength corresponding to the minimum reflectivity value of the narrow-band transmission peak, the center wavelength of the phase shift grating to be demodulated and the 3dB bandwidth to obtain the phase shift of the phase shift grating to be demodulated. The phase shift amount calculation formula of the phase shift grating to be demodulated is as follows:

wherein ,the method is characterized in that the method comprises the steps of representing the phase shift quantity of a phase shift grating to be demodulated, k represents the phase shift sensitivity, C represents an equation constant term, λc represents the wavelength corresponding to the minimum reflectivity value of a narrow-band transmission peak, λd represents the center wavelength of the phase shift grating to be demodulated, and Δλ represents the 3dB bandwidth.

It should be noted that, according to the phase shift amount of the phase shift grating to be demodulated obtained in step S106The phase shift amount of various phase shift gratings can be calculated in advance>Then, according to the magnitude of the phase shift amount of each phase shift grating, it is determined which data fitting algorithm is selected in step S104 to be appropriate, and for the phase shift amounts of different magnitudes, the accuracy that may be obtained by using different fitting algorithms is different.

In summary, according to the method provided by the second embodiment of the present invention, a series of steps including peak searching, wave cutting, fitting, calculating and the like are performed by using the reflection spectrum data of the phase shift grating to be demodulated, so as to obtain the center wavelength and the phase shift amount of the phase shift grating to be demodulated, so that real-time and rapid analysis of the phase shift grating can be realized, and the method has the characteristics of higher efficiency and stability. The method solves the problem that the central wavelength and the phase shift quantity of the phase shift grating cannot be effectively demodulated, and can further utilize the response difference of the central wavelength and the phase shift quantity to the external physical quantity change for sensing application.

As a third embodiment of the present invention, as shown in fig. 2, the present invention provides a data processing apparatus for demodulating a center wavelength and a phase shift amount of a phase shift grating, the apparatus comprising:

the peak searching algorithm module 101 is configured to calculate reflection spectrum data of the phase-shift grating to be demodulated by using a peak searching algorithm, so as to obtain peak wavelengths of reflection peaks in the reflection spectrum data of the phase-shift grating to be demodulated.

The comparison algorithm module 102 is configured to calculate each reflection peak-to-peak wavelength in the reflection spectrum data of the phase shift grating to be demodulated by using a comparison algorithm, so as to obtain a wavelength corresponding to a reflection minimum value of a narrow-band transmission peak between a reflection maximum peak-to-peak wavelength and a reflection sub-maximum peak-to-peak wavelength in the reflection spectrum data of the phase shift grating to be demodulated.

And the clipping algorithm module 103 is configured to remove, from the reflection spectrum data of the phase shift grating to be demodulated, the spectrum data of the narrow-band transmission peak between the maximum peak-to-peak wavelength of the reflectivity and the sub-maximum peak-to-peak wavelength of the reflectivity by using a clipping algorithm, so as to obtain the reflection spectrum data of the phase shift grating to be demodulated after clipping.

The data fitting module 104 is configured to perform data fitting on the reflection spectrum data of the phase shift grating to be demodulated after the filtering by using a data fitting algorithm to obtain a value of a preset parameter.

And the data analysis module 105 is configured to bring the values of the preset parameters into a preset center wavelength calculation formula and a preset 3dB bandwidth calculation formula, respectively, to perform calculation, so as to obtain the center wavelength and the 3dB bandwidth of the phase shift grating to be demodulated.

And the phase shift amount analysis module 106 is configured to perform phase shift amount analysis based on the wavelength corresponding to the minimum reflectance value of the narrowband transmission peak, the center wavelength of the phase shift grating to be demodulated, and the 3dB bandwidth, so as to obtain the phase shift amount of the phase shift grating to be demodulated.

In summary, according to the data processing device provided by the third embodiment of the present invention, the reflection spectrum data of the phase shift grating to be demodulated is utilized, and each module sequentially performs a series of operations such as peak searching, wave cutting, fitting, calculating, etc., so as to obtain the center wavelength and the phase shift amount of the phase shift grating to be demodulated, so that the real-time and rapid analysis of the phase shift grating can be realized, and the device has the characteristics of higher efficiency and stability. The method solves the problem that the central wavelength and the phase shift quantity of the phase shift grating cannot be effectively demodulated, and can further utilize the response difference of the central wavelength and the phase shift quantity to the external physical quantity change for sensing application.

As a fourth embodiment of the present invention, as shown in fig. 3, the present invention provides a data processing apparatus for demodulating a center wavelength and a phase shift amount of a phase shift grating, the apparatus comprising:

The comparison algorithm module 102 is configured to calculate each reflection peak-to-peak wavelength in the reflection spectrum data of the phase shift grating to be demodulated by using a comparison algorithm, so as to obtain a wavelength corresponding to a reflection minimum value of a narrow-band transmission peak between a reflection maximum peak-to-peak wavelength and a reflection sub-maximum peak-to-peak wavelength in the reflection spectrum data of the phase shift grating to be demodulated. The comparison algorithm in the comparison algorithm module 102 is any one of a bubbling ordering, a direct insertion ordering or a selection ordering algorithm.

And the clipping algorithm module 103 is configured to remove, from the reflection spectrum data of the phase shift grating to be demodulated, the spectrum data of the narrow-band transmission peak between the maximum peak-to-peak wavelength of the reflectivity and the sub-maximum peak-to-peak wavelength of the reflectivity by using a clipping algorithm, so as to obtain the reflection spectrum data of the phase shift grating to be demodulated after clipping. When the data fitting algorithm adopted in the data fitting module 104 is a quadratic function fitting algorithm, the clipping algorithm module 103 is further configured to:

If the reflectance maximum peak-to-peak wavelength λa is larger than the reflectance sub-maximum peak-to-peak wavelength λb in the reflectance spectrum data of the phase shift grating to be demodulated after the cutting, searching the corresponding wavelength λx of the first reflectance minimum point leftwards in the reflectance spectrum by the reflectance sub-maximum peak-to-peak wavelength λb, and searching the corresponding wavelength λy of the first reflectance minimum point rightwards in the reflectance spectrum by the reflectance maximum peak-to-peak wavelength λa;

or ,

if the reflectance maximum peak-to-peak wavelength λa is smaller than the reflectance sub-maximum peak-to-peak wavelength λb in the reflectance spectrum data of the phase shift grating to be demodulated after the cutting, searching the corresponding wavelength λx of the first reflectance minimum point leftwards in the reflectance spectrum by the reflectance maximum peak-to-peak wavelength λa, and searching the corresponding wavelength λy of the first reflectance minimum point rightwards in the reflectance spectrum by the reflectance sub-maximum peak-to-peak wavelength λb.

Removing spectral data with a wavelength value smaller than lambdax in the reflection spectrum data of the cut phase shift grating to be demodulated, removing spectral data with a wavelength value larger than lambday in the reflection spectrum data of the cut phase shift grating to be demodulated, and taking the rest of spectral data as the reflection spectrum data of the optimized cut phase shift grating to be demodulated.

The data fitting module 104 is configured to perform data fitting on the reflection spectrum data of the phase shift grating to be demodulated after the filtering by using a data fitting algorithm to obtain a value of a preset parameter. The data fitting algorithm employed in the data fitting module 104 is any one of a quadratic function fitting algorithm or a gaussian function fitting algorithm.

When 104 employs a quadratic function fitting algorithm, then the data fitting module 104 is specifically configured to:

Further, after the data fitting module 104 obtains the quadratic coefficient a, the first quadratic coefficient b and the constant term c, a mapping formula (1) between the wavelength and the reflectivity can be further obtained as follows:

R＝aλ ² +bλ+c (1)

or ,

when 104 employs a gaussian fitting algorithm, then the data fitting module 104 is specifically configured to:

Further, a position parameter μ and a distribution dispersion degree description parameter σ of a mapping curve between the wavelength and the reflectance generated by fitting, an equation coefficient a, an equation coefficient B, and a constant term D are obtained at 104

After that, 104 can further derive a mapping formula (2) between wavelength and reflectivity as follows:

The data analysis module 105 is configured to bring the values of the preset parameters into a preset center wavelength calculation formula and a preset 3dB bandwidth calculation formula, respectively, to perform calculation, so as to obtain a center wavelength and a 3dB bandwidth of the phase shift grating to be demodulated.

It should be noted that, when the quadratic function fitting algorithm is adopted in 104, the embodiment of the present invention further derives the first center wavelength calculation formula and the first 3dB bandwidth calculation formula by using the above-mentioned mapping formula (1) between the wavelength and the reflectivity. When a gaussian fitting algorithm is adopted in 104, the embodiment of the present invention further derives a second center wavelength calculation formula and a second 3dB bandwidth calculation formula by using the above-mentioned mapping formula (2) between wavelengths and reflectivities.

When a quadratic function fitting algorithm is employed in 104, then the data analysis module 105 is specifically configured to:

the quadratic term coefficient a, the first order term coefficient b and the constant term c are respectively brought into a first center wavelength calculation formula and a first 3dB bandwidth calculation formula to be calculated, so that the center wavelength lambdad and the 3dB bandwidth delta lambda of the phase shift grating to be demodulated are obtained, and the calculation formula is as follows:

λ _d ＝-b/2a (3)

or ,

when a gaussian fitting algorithm is employed at 104, then the data analysis module 105 is specifically configured to:

and respectively bringing the equation coefficient B, the position parameter mu and the distribution discrete degree description parameter sigma of the mapping curve between the wavelength and the reflectivity generated by fitting into a second center wavelength calculation formula and a second 3dB bandwidth calculation formula to calculate so as to obtain the center wavelength lambdad and the 3dB bandwidth delta lambda of the phase shift grating to be demodulated, wherein the calculation formula is as follows:

λ _d ＝μ (5)

and the phase shift amount analysis module 106 is configured to perform phase shift amount analysis based on the wavelength corresponding to the minimum reflectance value of the narrowband transmission peak, the center wavelength of the phase shift grating to be demodulated, and the 3dB bandwidth, so as to obtain the phase shift amount of the phase shift grating to be demodulated. In the phase shift amount analysis module 106, the phase shift amount calculation formula of the phase shift grating to be demodulated is as follows:

The phase shift amount of the phase shift grating to be demodulated obtained in 106The phase shift amount of various phase shift gratings can be calculated in advance>Then, according to the phase shift amount of each phase shift grating, it is determined 104 which data fitting algorithm is suitable, and for different phase shift amounts, the accuracy that may be obtained by using different fitting algorithms is different. In this embodiment, the phase shift amount analysis module 106 obtains the phase shift amount +.>Feedback to the data fitting module 104 so that the data fitting module 104 feeds back the amount of phase shift +.>And (3) automatically performing optimization judgment, and finally automatically selecting a proper data fitting algorithm for calculation.

In summary, according to the data processing device provided by the fourth embodiment of the present invention, the reflection spectrum data of the phase shift grating to be demodulated is utilized, and each module sequentially performs a series of operations such as peak searching, wave cutting, fitting, calculating, etc., so as to obtain the center wavelength and the phase shift amount of the phase shift grating to be demodulated, so that the real-time and rapid analysis of the phase shift grating can be realized, and the device has the characteristics of higher efficiency and stability. The method solves the problem that the central wavelength and the phase shift quantity of the phase shift grating cannot be effectively demodulated, and can further utilize the response difference of the central wavelength and the phase shift quantity to the external physical quantity change for sensing application.

As a fifth embodiment of the present invention, as shown in fig. 4, a system for demodulating center wavelength and phase shift of a phase shift grating is provided, and the system includes the data processing apparatus 10 described above; the system further comprises a light source unit 20, an optical coupling unit 30, a phase shift grating unit 40 and a spectrum acquisition unit 50.

An output port of the light source unit 20 is connected with a first port of the light coupling unit 30; an input port of the phase shift grating unit 40 is connected to a second port of the optical coupling unit 30; the third port of the optical coupling unit 30 is connected with the input port of the spectrum acquisition unit 50; the output port of the spectrum acquisition unit 50 is connected to the input port of the data processing device 10.

A light source unit 20 for emitting illumination light, which is transmitted to the light coupling unit 30;

an optical coupling unit 30 for transmitting the irradiation light to the phase shift grating unit 40;

a phase shift grating unit 40 for reflecting the irradiation light to form a reflection spectrum of a phase shift grating to be demodulated, the reflection spectrum of the phase shift grating to be demodulated being transmitted to the optical coupling unit 30;

the optical coupling unit 30 is further configured to transmit the reflection spectrum of the phase shift grating to be demodulated to the spectrum acquisition unit 50;

the spectrum acquisition unit 50 is used for acquiring reflection spectrum data of the phase shift grating to be demodulated, and the reflection spectrum data are transmitted to the data processing device 10;

The data processing device 10 is configured to calculate, using the reflection spectrum data of the phase shift grating to be demodulated, to obtain a center wavelength and a phase shift amount of the phase shift grating to be demodulated.

In summary, the system provided by the fifth embodiment of the present invention includes the data processing device, and the data processing device uses reflection spectrum data of the phase shift grating to be demodulated, and each module sequentially performs a series of operations such as peak searching, wave cutting, fitting, calculating, etc., so as to obtain a center wavelength and a phase shift amount of the phase shift grating to be demodulated. Therefore, the system adopting the data processing device can realize real-time and rapid analysis of the phase shift grating and has the characteristics of higher efficiency and stability. The method solves the problem that the central wavelength and the phase shift quantity of the phase shift grating cannot be effectively demodulated, and can further utilize the response difference of the central wavelength and the phase shift quantity to the external physical quantity change for sensing application. Meanwhile, the system further comprises a light source unit, an optical coupling unit, a phase shift grating unit and a spectrum acquisition unit, and the connecting structure among the elements is simple, so that the manufacturing cost is reduced, and the flexibility is higher.

As a sixth embodiment of the present invention, as shown in fig. 5, a system for demodulating center wavelength and phase shift of a phase shift grating according to the present invention includes the data processing apparatus 10 described above; the system further comprises a light source unit 20, an optical coupling unit 30, a phase shift grating unit 40 and a spectrum acquisition unit 50. The connection structure of each element in the system is as follows:

An output port of the light source unit 20 is connected with a first port of the light coupling unit 30; an input port of the phase shift grating unit 40 is connected to a second port of the optical coupling unit 30; the third port of the optical coupling unit 30 is connected with the input port of the spectrum acquisition unit 50; an output port of the spectrum acquisition unit 50 is connected with an input port of the data processing device 10; and an input port of the spectrum acquisition unit 50 is connected to an output port of the data processing device 10.

The light path transmission process among the elements in the system is as follows:

the light source unit 20 emits illumination light, which is transmitted to the light coupling unit 30. The light source unit 20 is any one of an stimulated spontaneous emission grating light source, a super-continuum light source, a tunable laser, or a scanning laser.

And an optical coupling unit 30 for transmitting the irradiation light to the phase shift grating unit 40. The optical coupling unit 30 is any one of a grating circulator, a star-type grating coupler, or a tree-type grating coupler.

The phase shift grating unit 40 is configured to reflect the above-mentioned irradiation light to form a reflection spectrum of the phase shift grating to be demodulated, and the reflection spectrum of the phase shift grating to be demodulated is transmitted to the optical coupling unit 30. The phase shift grating unit 40 is any one of a quartz grating, a plastic grating, or a waveguide grating having a phase shift.

The optical coupling unit 30 is further configured to shunt the reflection spectrum of the phase-shift grating to be demodulated, and transmit the reflection spectrum of one of the phase-shift grating to be demodulated to the spectrum acquisition unit 50.

The spectrum acquisition unit 50 is configured to acquire reflection spectrum data of the phase shift grating to be demodulated, and the reflection spectrum data is transmitted to the data processing device 10. The spectrum acquisition unit 50 is any one of a diffraction grating spectrometer, a prism spectrometer, an interference spectrometer, a micro spectrometer, or a grating demodulator.

The data processing device 10 is configured to calculate, using the reflection spectrum data of the phase shift grating to be demodulated, to obtain a center wavelength and a phase shift amount of the phase shift grating to be demodulated. The data processing device 10 is any one of an intelligent terminal, a DSP chip, an FPGA chip, or a single chip microcomputer in which data processing software is installed.

The data processing device 10 is further configured to transmit the center wavelength and the 3dB bandwidth of the obtained phase shift grating to be demodulated to the spectrum acquisition unit 50;

the spectrum acquisition unit 50 is further configured to determine a wavelength range and data acquisition accuracy of data acquisition by using a center wavelength and a 3dB bandwidth of the phase shift grating to be demodulated, so as to perform regulation in real time.

The invention can realize the double-parameter sensing of the center wavelength and the phase shift quantity of the phase shift grating, and the sensing application is carried out by utilizing the response difference of the center wavelength and the phase shift quantity to the external physical quantity change. It is worth to say that although there are studies reporting that the sensing application is performed by using the narrow-band transmission peak of the phase-shift grating, the center wavelength of the phase-shift grating is different from the narrow-band transmission peak of the phase-shift grating.

In summary, the system provided by the sixth embodiment of the present invention includes the data processing device, and the device uses the reflection spectrum data of the phase shift grating to be demodulated, and each module sequentially performs a series of operations such as peak searching, wave cutting, fitting, calculating, etc., so as to obtain the center wavelength and the phase shift amount of the phase shift grating to be demodulated. Therefore, the system adopting the data processing device can realize real-time and rapid analysis of the phase shift grating, simply and efficiently calculate the center wavelength and the phase shift amount of the phase shift grating, and has the characteristic of being more stable. The method solves the problem that the central wavelength and the phase shift quantity of the phase shift grating cannot be effectively demodulated, and can further utilize the response difference of the central wavelength and the phase shift quantity to the external physical quantity change for sensing application. Meanwhile, the system further comprises a light source unit, an optical coupling unit, a phase shift grating unit and a spectrum acquisition unit, and the connecting structure among the elements is simple, so that the manufacturing cost is reduced.

As a seventh embodiment of the present invention, as shown in fig. 6, the present embodiment provides a system for knowing the center wavelength and the amount of phase shift of a phase shift grating. The system adopts a computer as a data processing device 10, a low-bias full-broadband stimulated spontaneous emission (ASE) light source unit 20, an optical fiber circulator as an optical coupling unit 30, a phase-shift fiber grating written by a femtosecond laser line-by-line method as a phase-shift grating unit 40 and a spectrometer (OSA) as a spectrum acquisition unit 50. First, the first port b1 of the optical fiber circulator is connected with the output port a of the light source, and the second port b2 of the optical fiber circulator is connected with the phase shift grating input port c. The third port b3 of the optical fiber circulator is connected with the input port d1 of the spectrometer, and the output port d2 of the spectrometer is connected with the input port e of the computer. The emergent light of the light source is conducted into the phase shift grating through the optical fiber circulator, reflected by the phase shift grating, conducted into the spectrometer through the optical fiber circulator again, and the spectrum signal of the phase shift grating is received and collected by the spectrometer. In order to reduce interference signals of reflected light, the optical fiber at the tail end of the phase shift grating is treated to a certain extent, and the reflection of the end face of the optical fiber is reduced.

The spectrum data collected by the spectrometer is led into a computer through an output port d2 of the spectrometer to obtain the original reflection spectrum of the phase shift grating. Fig. 7 is a reflection spectrum of the phase shift grating used in the present embodiment. And manually searching the peak value of the reflection spectrum, manually searching the peak value wavelength of the maximum reflectivity in the reflection spectrum of the phase shift grating, and manually searching the peak value wavelength of the sub-maximum reflectivity in the reflection spectrum of the phase shift grating to obtain the maximum reflectivity peak value wavelength of λa= 1549.96, wherein the corresponding reflectivity is 0.99, the sub-maximum reflectivity peak value wavelength of λb= 1549.34, and the corresponding reflectivity is 0.59. After the peak positions are determined, an extraction of the wavelength corresponding to the minimum reflectance of the narrowband transmission peak between the two peaks is performed, in this example at λc= 1549.59. Then, the spectral data between the reflectance maximum peak-to-peak wavelength λa= 1549.96 and the reflectance next-to-maximum peak-to-peak wavelength λb= 1549.34 is cut off, and as shown in fig. 8, the phase shift grating reflection spectrum after the narrow-band transmission peak spectral data is removed is obtained. As shown in fig. 9, to perform gaussian fitting on the data after clipping, an image of the fitting equation (i.e., a mapping curve between wavelength and reflectivity generated by fitting) is shown as a smoother line in fig. 9, and after fitting, substantially the expression of the mapping curve between wavelength and reflectivity (i.e., a mapping equation between wavelength and reflectivity) is shown as follows:

And (3) carrying out data analysis on the mapping formula (8) between the wavelength and the reflectivity to deduce that the center wavelength and the phase shift are calculated by adopting the formula (5) and the formula (6). Finally, the center wavelength demodulation formula (5) (i.e. the second center wavelength calculation formula) and the 3dB bandwidth demodulation formula (6) (i.e. the second 3dB bandwidth calculation formula) are calculated to obtain the center wavelength λd=1549.77 of the phase shift grating, and the 3dB bandwidth Δλ=0.84. This is substantially consistent with the phase shift grating design center wavelength λ0=1550, 3db bandwidth Δλ0=0.92.

In summary, the system provided by the seventh embodiment of the present invention can effectively demodulate the center wavelength and the amount of phase shift of the phase shift grating.

As an eighth embodiment of the present invention, the present embodiment provides a data processing apparatus that simulates a phase shift grating spectrum by software as input data to the data processing apparatus, and thus does not require a light source unit, an optical coupling unit, a phase shift grating unit, and a spectrum acquisition unit. Through numerical simulation, the phase shift grating spectrum data can be conveniently simulated by means of a phase shift grating simulation program. By setting the parameters of the phase shift grating, any spectrum type of the phase shift grating can be simulated. As shown in fig. 10, to set the center wavelength λ0= 1550.11, the phase shift amount is set to be Is a phase shift grating reflection spectrum of (c). Manual peak searching is carried out on a reflection spectrum of the phase shift grating, the peak wavelength of each peak in the spectrum is shown in FIG. 10, wherein the peak wavelength λa=λ3 of the maximum reflectivity peak in the reflection spectrum, and the next maximum reflectivity peak in the reflection spectrumThe peak wavelength λb=λ2, and the wavelength λc corresponding to the reflectance minimum of the narrow-band transmission peak between the reflectance maximum peak wavelength and the reflectance next-maximum peak wavelength in the reflection spectrum are shown in fig. 10. In this example, a quadratic fitting method is used to fit the data, due to λb<And searching the wavelength lambday corresponding to the first minimum value of the reflectivity at the right side of the maximum peak-to-peak wavelength lambdaa, and the wavelength lambdax corresponding to the first minimum value of the reflectivity at the left side of the sub-maximum peak-to-peak wavelength lambdab. A schematic has also been marked in fig. 10.

The spectrum data on the right side of the wavelength lambday corresponding to the first minimum value to the right of the first minimum value in the reflection spectrum of the phase shift grating is cut off, so that the spectrum data on the right side of the wavelength lambday corresponding to the first minimum value to the left of the reflection rate sub-peak wavelength lambdab in the reflection spectrum of the phase shift grating is obtained, and the spectrum shown in fig. 11 is obtained. Performing secondary fitting on the rest data of the reflection spectrum of the phase shift grating to obtain values of preset parameters, so that a mapping formula between the wavelengths and the reflectivities according to the values of the preset parameters is as follows:

R＝-51.19λ ² +158711.4λ-1.23e8 (9)

Then, the formula (3) and the formula (4) can be finally derived from the formula (9). From the center wavelength demodulation formula (3) (i.e., the first center wavelength calculation formula) and the 3dB bandwidth demodulation formula (4) (i.e., the first 3dB bandwidth calculation formula), the center wavelength λd=1550.21 and the 3dB bandwidth Δλ=0.21 of the phase shift grating are calculated, which substantially coincides with the design center wavelength λ0=1550.11 and the 3dB bandwidth Δλ0=0.18 of the phase shift grating.

In summary, the device provided by the eighth embodiment of the present invention can effectively demodulate the center wavelength and the amount of phase shift of the phase shift grating.

The existing optical fiber sensing demodulation technology and method mainly aim at uniform optical fiber gratings, the detection range is larger than 100nm, the precision is higher than 1pm, the multi-pass rapid scanning can be realized, the demodulation instrument with high precision and large range is usually expensive, the prior art is not suitable for demodulating the phase-shift optical fiber gratings, and therefore the phase-shift optical fiber gratings are difficult to be applied to optical fiber sensing on a large scale, and the method, the device or the system provided by the invention are more suitable for demodulating the phase-shift optical fiber gratings, and the method is simple, convenient and flexible, the structure of the device or the system is simple and flexible, the manufacturing cost is low, and the method is more suitable for large-scale application.

The foregoing description of the preferred embodiment of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.

Claims

1. A method of demodulating a center wavelength and a phase shift amount of a phase shift grating, the method comprising:

Step D: performing data fitting on the reflection spectrum data of the phase shift grating to be demodulated after the cutting by using a quadratic function fitting algorithm to obtain a value of a preset parameter;

or, performing data fitting on the reflection spectrum data of the phase shift grating to be demodulated after the cutting by using a Gaussian function fitting algorithm to obtain a value of a preset parameter;

step E: respectively bringing the values of the preset parameters into a preset center wavelength calculation formula and a preset 3dB bandwidth calculation formula to calculate so as to obtain the center wavelength and the 3dB bandwidth of the phase shift grating to be demodulated; specifically, the calculation process is as follows:

carrying out calculation by using a quadratic function fitting algorithm by taking a quadratic term coefficient a, a primary term coefficient b and a constant term c into a first center wavelength calculation formula and a first 3dB bandwidth calculation formula respectively to obtain the center wavelength lambdad and the 3dB bandwidth delta lambda of the phase shift grating to be demodulated; wherein the first center wavelength calculation formula is expressed as:

λ _d ＝-b/2a；

the first 3dB bandwidth calculation formula is expressed as:

or, using a Gaussian function fitting algorithm to bring the equation coefficient B, the position parameter mu and the distribution discrete degree description parameter sigma of the mapping curve between the wavelength and the reflectivity generated by fitting into a second center wavelength calculation formula and a second 3dB bandwidth calculation formula to calculate so as to obtain the center wavelength lambdad and the 3dB bandwidth delta lambda of the phase shift grating to be demodulated; wherein the second center wavelength calculation formula is expressed as:

λ _d ＝μ；

The second 3dB bandwidth calculation formula is expressed as:

2. The method of claim 1, wherein when said step D employs a quadratic function fitting algorithm, then said step E is preceded by the further step of:

3. The method of claim 2, wherein if the quadratic function fitting algorithm is adopted in the step D, the step D specifically includes:

performing data fitting on the reflection spectrum data of the phase shift grating to be demodulated after optimization and cutting by using the quadratic function fitting algorithm to obtain the quadratic term coefficient a, the primary term coefficient b and the constant term c;

if the step D adopts the gaussian fitting algorithm, the step D specifically includes:

and performing data fitting on the reflection spectrum data of the phase shift grating to be demodulated after the cutting by using the Gaussian function fitting algorithm to obtain the equation coefficient B, the position parameter mu of a mapping curve between the wavelength and the reflectivity generated by fitting and the distribution discrete degree description parameter sigma.

4. The method according to claim 1, wherein in the step F, the phase shift amount of the phase shift grating to be demodulated is calculated as follows:

5. A data processing apparatus for demodulating a center wavelength and a phase shift amount of a phase shift grating, the apparatus comprising:

the comparison algorithm module is used for calculating the peak value wavelength of each reflection peak in the reflection spectrum data of the phase shift grating to be demodulated by utilizing a comparison algorithm to obtain the wavelength corresponding to the minimum value of the reflectivity of the narrow-band transmission peak between the maximum peak value wavelength of the reflectivity and the sub-maximum peak value wavelength of the reflectivity in the reflection spectrum data of the phase shift grating to be demodulated;

The data fitting module is used for carrying out data fitting on the reflection spectrum data of the phase shift grating to be demodulated after the cutting by utilizing a quadratic function fitting algorithm so as to obtain the value of a preset parameter;

the data analysis module is used for respectively bringing the values of the preset parameters into a preset center wavelength calculation formula and a preset 3dB bandwidth calculation formula to calculate so as to obtain the center wavelength and the 3dB bandwidth of the phase shift grating to be demodulated; specifically, the calculation process is as follows:

λ _d ＝-b/2a；

the first 3dB bandwidth calculation formula is expressed as:

λ _d ＝μ；

The second 3dB bandwidth calculation formula is expressed as:

6. The apparatus of claim 5, wherein when a quadratic function fitting algorithm is employed in the data fitting module, then the clipping algorithm module is further configured to:

7. A system for demodulating the center wavelength and the amount of phase shift of a phase shift grating, said system comprising a data processing apparatus according to claim 5 or 6; the system also comprises a light source unit, a phase shift grating unit, an optical coupling unit and a spectrum acquisition unit;

8. The system of claim 7, wherein:

the data processing device is further used for transmitting the obtained center wavelength and 3dB bandwidth of the phase shift grating to be demodulated to the spectrum acquisition unit;

9. The system of claim 7, wherein the data processing device is any one of a smart terminal, a DSP chip, an FPGA chip, or a single chip microcomputer with data processing software installed.