CN118329090B - Optical fiber grating signal high-speed measurement method and system based on double-edge filtering - Google Patents

Abstract

The invention relates to the technical field of fiber bragg grating demodulation, and provides a fiber bragg grating signal high-speed measurement method and a system based on double-edge filtering, wherein the method comprises the following steps: inputting a first optical signal with a first preset wavelength at a first port of the fiber grating, inputting a second optical signal with a second preset wavelength at a second port of the fiber grating, collecting the first optical intensity signal output by the first port of the fiber grating and the second optical intensity signal output by the second port, calculating characteristic parameters of the fiber grating based on the first optical intensity signal and the second optical intensity signal, and calculating the center wavelength of the fiber grating according to a characteristic parameter curve of the fiber grating. The invention does not need to adjust the wavelength of the optical signal input into the fiber grating in the formal measurement stage of the center wavelength of the fiber grating, simplifies the measurement flow, has simple processing flow of the measurement result, does not need to process a large amount of spectrum data, and improves the measurement speed.

Description

A high-speed measurement method and system for fiber grating signals based on double-edge filtering

Technical Field

The invention relates to the technical field of fiber Bragg grating demodulation, and in particular to a fiber Bragg grating signal high-speed measurement method and system based on double-edge filtering.

Background Art

Fiber Bragg grating sensors reflect changes in external physical parameters through changes in the central wavelength. By demodulating the wavelength information, changes in parameters such as temperature, vibration, movement, and strain can be obtained. Therefore, in the fiber Bragg grating sensing system, the demodulation of the fiber Bragg grating sensor wavelength is particularly important, and the demodulation speed of the fiber Bragg grating sensor wavelength also determines the response speed of the fiber Bragg grating sensor.

At present, there are two main methods for measuring fiber Bragg grating signals from the perspective of optical signal acquisition. One is to collect a wide range of spectra, find fiber Bragg grating features from the collected spectral data, and calculate the change in the central wavelength of the fiber Bragg grating; the other is to convert the change in the central wavelength of the fiber Bragg grating into a change in low-dimensional features such as a single light intensity through filtering, matching and other means, and calculate the change in the central wavelength based on their corresponding relationship. Among them, the former requires the collection of a wide range of spectral data, which will result in a low demodulation rate of the central wavelength of the fiber Bragg grating, and cannot meet the measurement requirements of high-speed signals; while the latter requires accurate measurement of light intensity, which is easily affected by external factors and has low accuracy.

Summary of the invention

In order to solve the above technical problem or at least partially solve the above technical problem, the present invention provides a high-speed measurement method and system for fiber Bragg grating signals based on double-edge filtering.

One aspect of the present invention provides a high-speed measurement method for fiber Bragg grating signals based on double-edge filtering, the method comprising:

S1. Input a first optical signal of a first preset wavelength to a first port of a fiber Bragg grating, and input a second optical signal of a second preset wavelength to a second port of a fiber Bragg grating, wherein the first preset wavelength and the second preset wavelength are respectively:

λ ₁ =λ ₀ +Δλ

λ ₂ =λ ₀ -Δλ

Wherein, λ ₀ represents the initial center wavelength of the fiber grating, Δλ represents the preset wavelength difference, λ ₁ represents the first preset wavelength, and λ ₂ represents the second preset wavelength;

S2, collecting a first light intensity signal output from a first port of the fiber Bragg grating and a second light intensity signal output from a second port, and calculating characteristic parameters of the fiber Bragg grating based on the first light intensity signal and the second light intensity signal, the first light intensity signal is the sum of the reflected light intensity of the first light signal passing through the fiber Bragg grating and the transmitted light intensity of the second light signal passing through the fiber Bragg grating, the second light intensity signal is the sum of the reflected light intensity of the second light signal passing through the fiber Bragg grating and the transmitted light intensity of the first light signal passing through the fiber Bragg grating, the calculation model of the characteristic parameters is:

or

Wherein, R represents the characteristic parameter, _P1 represents the first light intensity signal, and _P2 represents the second light intensity signal;

S3. Acquire a characteristic parameter curve of the fiber Bragg grating, and calculate the current center wavelength of the fiber Bragg grating based on the characteristic parameter curve, wherein the characteristic parameter curve is a relationship curve between the center wavelength of the fiber Bragg grating and the characteristic parameter.

Furthermore, before executing step S1, the method further includes:

Inputting an optical signal with a sequentially changing wavelength into the first port or the second port of the fiber Bragg grating, obtaining the reflected light intensity of the fiber Bragg grating corresponding to the optical signals with different wavelengths, so as to collect the reflection spectrum curve of the fiber Bragg grating;

Acquire the initial center wavelength and half-maximum full width of the fiber grating based on the reflection spectrum curve of the fiber grating;

The wavelength difference is calculated according to the full width at half maximum of the fiber grating, and the calculation formula is as follows:

Wherein, FWHM represents the full width at half maximum of the fiber Bragg grating.

Further, after calculating the wavelength difference according to the half-width at half maximum of the fiber grating, the method further includes:

S11, inputting a first optical signal of a first preset wavelength into a first port of the fiber Bragg grating, and inputting a second optical signal of a second preset wavelength into a second port of the fiber Bragg grating;

S12, controlling the fiber Bragg grating to change the central wavelength to the target central wavelength, and obtaining a first light intensity signal output from the first port of the fiber Bragg grating and a second light intensity signal output from the second port;

S13, calculating a characteristic parameter corresponding to the target central wavelength according to the first light intensity signal and the second light intensity signal corresponding to the target central wavelength;

S14, selecting a different target central wavelength and repeatedly performing the operations of step S12-step S13 to obtain a plurality of different groups of data sampling points, each group of data sampling points including a different target central wavelength and a characteristic parameter corresponding to the corresponding target central wavelength;

S15, fitting a relationship curve between the central wavelength of the fiber Bragg grating and the change of the characteristic parameter according to the multiple groups of different data sampling points to obtain the characteristic parameter curve.

Furthermore, the wavelength range of the target central wavelength is [λ ₀ -Δλ,λ ₀ +Δλ].

Another aspect of the present invention further provides a high-speed measurement system for fiber Bragg grating signals based on double-edge filtering, the system comprising:

The first optical signal transmitting device is used to transmit a first optical signal of a first preset wavelength, wherein the first preset wavelength is:

λ ₁ =λ ₀ +Δλ

Wherein, λ ₀ represents the initial center wavelength of the fiber grating, Δλ represents the preset wavelength difference, and λ ₁ represents the first preset wavelength;

A first circulator, wherein a first port of the first circulator is connected to the first optical signal transmitting device, and a second port of the first circulator is connected to a first port of a fiber Bragg grating, and is used to input the first optical signal into the first port of the fiber Bragg grating;

The second optical signal transmitting device is used to transmit a second optical signal of a second preset wavelength, wherein the second preset wavelength is:

λ ₂ =λ ₀ -Δλ

Wherein, λ ₂ represents the second preset wavelength;

A second circulator, wherein a first port of the second circulator is connected to the second optical signal transmitting device, and a second port of the second circulator is connected to a second port of the fiber Bragg grating, and is used to input the second optical signal to the second port of the fiber Bragg grating;

a first photoelectric conversion device, connected to the third port of the first circulator, for receiving, through the first circulator, reflected light of the first optical signal passing through the fiber grating and transmitted light of the second optical signal passing through the fiber grating, and converting the optical signals into electrical signals to obtain a first light intensity signal;

A second photoelectric conversion device is connected to the third port of the second circulator, and is used for receiving the reflected light of the second optical signal passing through the fiber grating and the transmitted light of the first optical signal passing through the fiber grating through the second circulator, and converting the optical signal into an electrical signal to obtain a second light intensity signal.

Furthermore, the system further comprises:

The demodulation processing device is used to receive the first light intensity signal and the second light intensity signal, and calculate the characteristic parameter of the fiber Bragg grating based on the first light intensity signal and the second light intensity signal, and the calculation model of the characteristic parameter R is:

or

Wherein, R represents the characteristic parameter, _P1 represents the first light intensity signal, and _P2 represents the second light intensity signal;

The demodulation processing device is also used to obtain the characteristic parameter curve of the fiber Bragg grating, and calculate the current center wavelength of the fiber Bragg grating based on the characteristic parameter curve, wherein the characteristic parameter curve is a relationship curve between the center wavelength of the fiber Bragg grating and the characteristic parameter.

Furthermore, the first optical signal transmitting device and the second optical signal transmitting device are tunable laser transmitters.

The high-speed measurement method and system of fiber Bragg grating signals based on double-edge filtering provided by the present invention utilizes the bidirectional transmission characteristics of optical fiber, and simultaneously inputs a first optical signal of a first preset wavelength and a second optical signal of a second preset wavelength at both ends of the fiber Bragg grating. In the measurement stage of the center wavelength of the fiber Bragg grating, it is not necessary to adjust the wavelength of the optical signal input to the fiber Bragg grating, which simplifies the measurement process and greatly improves the measurement speed. Moreover, the characteristic parameters calculated based on the first light intensity signal output from the first port and the second light intensity signal output from the second port only need to perform division and logarithm operations to calculate the current center wavelength of the fiber Bragg grating, so that the processing flow of the measurement results is simple, and there is no need to process a large amount of spectral data. The conversion of the characteristic parameters to the center wavelength of the fiber Bragg grating only needs to perform a few addition and multiplication operations according to the requirements for measurement accuracy, which puts less pressure on the computing device and can be deployed on edge devices with low computing power, further improving the measurement speed.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

FIG1 is a schematic diagram of the structure of a high-speed measurement system for fiber Bragg grating signals based on double-edge filtering provided by an embodiment of the present invention;

FIG2 is a graph showing the corresponding relationship between the reflection spectrum of the fiber Bragg grating and the optical signal provided by an embodiment of the present invention;

FIG3 is a graph showing the corresponding relationship between the transmission spectrum of a fiber Bragg grating and an optical signal provided by an embodiment of the present invention;

FIG4 is a graph showing the variation of the light intensity signal output by the fiber Bragg grating according to the embodiment of the present invention with the central wavelength;

FIG5 is a characteristic parameter curve of a fiber Bragg grating according to an embodiment of the present invention;

FIG6 is a schematic flow chart of a high-speed measurement method for fiber Bragg grating signals based on double-edge filtering provided in an embodiment of the present invention.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

In the prior art, the demodulation corresponding to the central wavelength of the fiber Bragg grating is usually performed by utilizing the reflection characteristics of the fiber Bragg grating, and determining the central wavelength of the fiber Bragg grating based on the peak value in the reflection spectrum of the fiber Bragg grating. The present invention utilizes the bidirectional transmission characteristics of the optical fiber, inputs the optical signal at both ends of the fiber Bragg grating at the same time and receives the light intensity signal output from both ends of the fiber Bragg grating, forms a bidirectional measurement optical path of the optical fiber, locates the waveform characteristics of the fiber Bragg grating reflection spectrum through the bidirectional measurement signal, and realizes the high-speed measurement of the fiber Bragg grating signal.

FIG1 shows a schematic structural diagram of a high-speed fiber Bragg grating signal measurement system based on double-edge filtering according to an embodiment of the present invention. The principle of high-speed fiber Bragg grating signal measurement provided by the present invention will be described in detail below in conjunction with FIG1 .

As shown in FIG1 , the fiber Bragg grating signal high-speed measurement system based on double-edge filtering provided in an embodiment of the present invention includes: a first circulator 10 and a second circulator 20, a fiber Bragg grating 01 is connected between the second port of the first circulator 10 and the second port of the second circulator 20, the first port of the first circulator 10 is connected to a first optical signal transmitting device 11, and the third port is connected to a first photoelectric conversion device 12, the first port of the second circulator 20 is connected to a second optical signal transmitting device 21, and the third port is connected to a second photoelectric conversion device 22.

It should be noted that, in order to facilitate identification of different optical signals, in the embodiment of the present invention, a dotted line is used to represent the first optical signal emitted by the first optical signal emitting device 11, and a solid line is used to represent the second optical signal emitted by the second optical signal emitting device 21. Corresponding to the signal emitting device, a dotted line is used to represent the light intensity signal received by the first photoelectric conversion device 12, and a solid line is used to represent the light intensity signal received by the second photoelectric conversion device 22.

As can be seen from the optical path diagram in FIG1 , when measuring the signal of the fiber Bragg grating 01, the first optical signal emitted by the first optical signal transmitting device 11 enters the first end of the fiber Bragg grating 01 through the first port and the second port of the first circulator 10, and a portion of the first optical signal is received by the first photoelectric conversion device 12 through the third port of the first circulator 10 due to the reflection of the grating, while another portion of the first optical signal is received by the second photoelectric conversion device 22 through the second port and the third port of the second circulator 20 through the grating. Similarly, the second optical signal emitted by the second optical signal transmitting device 21 enters the second end of the fiber Bragg grating 01 through the first port and the second port of the second circulator 20, and a portion of the first optical signal is received by the second photoelectric conversion device 22 through the third port of the second circulator 20 due to the reflection of the grating, while another portion of the second optical signal is received by the first photoelectric conversion device 12 through the second port and the third port of the second circulator 20 through the grating.

Further, the light intensity signal received by the first photoelectric conversion device 12 is the sum of the reflection spectrum of the first optical signal transmitting device 11 and the transmission spectrum of the second optical signal transmitting device 21, and the light intensity signal received by the second photoelectric conversion device 22 is the sum of the reflection spectrum of the second optical signal transmitting device 21 and the transmission spectrum of the first optical signal transmitting device 11. In a specific embodiment of the present invention, the first photoelectric conversion device 12 and the second photoelectric conversion device 22 can both be photodiodes.

Furthermore, the first photoelectric conversion device 12 and the second photoelectric conversion device 22 convert the received optical signal into an electrical signal and output it to the demodulation processing device, so that the demodulation processing device can analyze and calculate to obtain the current center wavelength of the fiber Bragg grating 01. In the subsequent description of the present invention, _P1 is used to represent the first light intensity signal, which characterizes the signal strength of the first light signal, and _P2 is used to represent the second light intensity signal, which characterizes the signal strength of the second light signal.

Further, Fig. 2 shows the corresponding relationship between the reflection spectrum of the fiber Bragg grating 01 and the first optical signal and the second optical signal. Fig. 3 shows the corresponding relationship between the transmission spectrum of the fiber Bragg grating 01 and the first optical signal and the second optical signal.

As can be seen from FIG. 2 and FIG. 3, when the central wavelength of the fiber Bragg grating 01 is the initial central wavelength, 1/2 of the first optical signal is reflected by the fiber Bragg grating 01 back to the first photoelectric conversion device 12, and the other 1/2 is transmitted by the fiber Bragg grating 01 to the second photoelectric conversion device 22. 1/2 of the second optical signal emitted by the second optical signal transmitting device 21 is reflected by the fiber Bragg grating 01 back to the second photoelectric conversion device 22, and the other 1/2 is transmitted by the fiber Bragg grating 01 to the first photoelectric conversion device 12. At this time, the first optical signal received by the first photoelectric conversion device 12 and the second optical signal received by the second photoelectric conversion device 22 are the same, as shown in FIG. 4 at the intersection of the first light intensity signal and the second light intensity signal.

Further, when the central wavelength of the fiber Bragg grating 01 is smaller than the initial central wavelength, the second optical signal generated by the second optical signal transmitting device 21 is closer to the central wavelength of the fiber Bragg grating 01, so the optical signal intensity of the first optical signal reflected from the fiber Bragg grating 01 to the first photoelectric conversion device 12 is reduced, and the optical signal intensity transmitted from the fiber Bragg grating 01 to the second photoelectric conversion device 22 is enhanced, and the corresponding optical signal intensity of the second optical signal transmitted from the fiber Bragg grating 01 to the first photoelectric conversion device 12 is reduced, and the optical signal intensity reflected from the fiber Bragg grating 01 to the second photoelectric conversion device 22 is enhanced. The superposition of the two makes the signal intensity of the first light intensity signal smaller than the signal intensity of the second light intensity signal, and as the central wavelength of the fiber Bragg grating 01 gradually decreases, the signal intensity of the first light intensity signal becomes smaller and smaller, and the signal intensity of the second light intensity signal becomes stronger and stronger, as shown in the curve part on the left side of the dotted line perpendicular to the x-axis shown in FIG4.

Further, when the center wavelength of the fiber Bragg grating 01 is greater than the initial center wavelength, the first optical signal generated by the first optical signal transmitting device 11 is closer to the center wavelength of the fiber Bragg grating 01, so the intensity of the optical signal of the first optical signal reflected from the fiber Bragg grating 01 to the first photoelectric conversion device 12 is enhanced, and the intensity of the optical signal transmitted from the fiber Bragg grating 01 to the second photoelectric conversion device 22 is reduced, and the intensity of the optical signal of the corresponding second optical signal transmitted from the fiber Bragg grating 01 to the first photoelectric conversion device 12 is enhanced, and the intensity of the optical signal reflected from the fiber Bragg grating 01 to the second photoelectric conversion device 22 is reduced. At this time, the signal intensity of the first light intensity signal is greater than the signal intensity of the second light intensity signal, and as the center wavelength of the fiber Bragg grating 01 gradually increases, the signal intensity of the first light intensity signal becomes larger and larger, and the signal intensity of the second light intensity signal becomes smaller and smaller, as shown in the curve part on the right side of the dotted line perpendicular to the x-axis shown in FIG4.

From the above analysis, it can be seen that the high-speed measurement system for fiber Bragg grating signals based on double-edge filtering in the embodiment of the present invention can transmit optical signals of different wavelengths through the first optical signal transmitting device 11 and the second optical signal transmitting device 21, and the light intensity signals received by the first photoelectric conversion device 12 and the second photoelectric conversion device 22, and determine the characteristic parameters and characteristic parameter curves based on the light intensity signals received by the first photoelectric conversion device 12 and the second photoelectric conversion device 22, and analyze and calculate the current center wavelength of the fiber Bragg grating 01 based on the characteristic parameters and the characteristic parameter curve.

Specifically, in the fiber Bragg grating signal high-speed measurement system based on double-edge filtering provided by the present invention:

The first optical signal transmitting device 11 is used to transmit a first optical signal of a first preset wavelength, where the first preset wavelength is:

λ ₁ =λ ₀ +Δλ (1)

Wherein, λ ₀ represents the initial center wavelength of the fiber grating 01, Δλ represents the preset wavelength difference, and λ ₁ represents the first preset wavelength;

A first circulator 10, wherein a first port of the first circulator 10 is connected to the first optical signal transmitting device 11, and a second port of the first circulator 10 is connected to a first port of a fiber Bragg grating 01, and is used to input the first optical signal to the first port of the fiber Bragg grating 01;

The second optical signal transmitting device 21 is used to transmit a second optical signal of a second preset wavelength, where the second preset wavelength is:

λ ₂ =λ ₀ -Δλ (2)

Wherein, λ ₂ represents the second preset wavelength;

A second circulator 20, wherein a first port of the second circulator 20 is connected to the second optical signal transmitting device 21, and a second port of the second circulator 20 is connected to a second port of the fiber Bragg grating 01, and is used to input the second optical signal to the second port of the fiber Bragg grating 01;

A first photoelectric conversion device 12, which is connected to the third port of the first circulator 10, and is used to receive the reflected light of the first optical signal passing through the fiber grating 01 and the transmitted light of the second optical signal passing through the fiber grating 01 through the first circulator 10, and convert the optical signals into electrical signals to obtain a first light intensity signal;

A second photoelectric conversion device 22 is connected to the third port of the second circulator 20, and is used for receiving the reflected light of the second optical signal passing through the fiber grating 01 and the transmitted light of the first optical signal passing through the fiber grating 01 through the second circulator 20, and converting the optical signal into an electrical signal to obtain a second light intensity signal.

Further, in a preferred embodiment of the present invention, the preset wavelength difference Δλ satisfies the following calculation formula:

Wherein, FWHM represents the full width at half maximum of the fiber Bragg grating 01. The full width at half maximum of the fiber Bragg grating 01 describes the spectral width at half the peak intensity in the grating reflection or transmission spectrum. When the central wavelength of the fiber Bragg grating 01 is the initial central wavelength, if the wavelength of the first optical signal is λ ₁ =λ ₀ +Δλ, at this time, the reflected light intensity and the transmitted light intensity of the first optical signal passing through the fiber Bragg grating 01 are half each, and the second optical signal also satisfies the above rule.

Furthermore, since the first light intensity signal and the second light intensity signal show a regular change trend with the change of the central wavelength of the fiber Bragg grating 01, the optical path characteristics of the fiber Bragg grating 01 signal high-speed measurement system based on double-edge filtering in the embodiment of the present invention set the characteristic parameters of the system as follows:

Wherein, R represents the characteristic parameter, _P1 represents the first light intensity signal, and _P2 represents the second light intensity signal. The corresponding relationship between the characteristic parameter and the central wavelength of the fiber Bragg grating 01 can be obtained by calibration, as shown in FIG5 , which shows the corresponding relationship between the current central wavelength of the fiber Bragg grating 01 and the characteristic parameter.

Furthermore, based on the characteristic parameter curve shown in FIG5 and the characteristic parameters measured and calculated in actual applications, the current center wavelength of the optical fiber can be obtained in real time. Therefore, the high-speed measurement system for fiber Bragg grating 01 signals based on double-edge filtering provided in an embodiment of the present invention also includes a demodulation processing device, and the demodulation processing device at least includes a control module, a calculation module and a storage module. The control module is used to control the first optical signal transmitting device 11 and the first optical signal transmitting device 22 to transmit optical signals, and the calculation module calculates the center wavelength of the fiber Bragg grating according to the acquired light intensity signal. The storage device is used to store the characteristic parameter curve, so as to obtain the characteristic parameter curve of the fiber Bragg grating 01 from the storage medium when measuring the current center wavelength of the fiber Bragg grating 01.

Specifically, the demodulation processing device provided in the embodiment of the present invention is used to receive a first light intensity signal and a second light intensity signal, and calculate characteristic parameters of the fiber Bragg grating 01 based on the first light intensity signal and the second light intensity signal. The calculation model diagram of the characteristic parameters is shown in formula (4).

The demodulation processing device is also used to obtain the characteristic parameter curve of the fiber Bragg grating 01, and calculate the current central wavelength of the fiber Bragg grating 01 based on the characteristic parameter curve, wherein the characteristic parameter curve is a relationship curve between the central wavelength of the fiber Bragg grating 01 and the characteristic parameter.

Furthermore, in a preferred embodiment of the present invention, the first optical signal transmitting device 11 and the second optical signal transmitting device 21 are tunable laser transmitters. The first optical signal output by the first optical signal transmitting device 11 is a narrow line width light with a wavelength of λ ₀ +Δλ, and the second optical signal output by the first optical signal transmitting device 11 is a narrow line width light with a wavelength of λ ₀ -Δλ.

The fiber Bragg grating 01 signal high-speed measurement system based on double-edge filtering provided by the embodiment of the present invention has a simple system structure and has no other optoelectronic devices except a tunable laser and a photodiode, which greatly reduces the system complexity and improves the system reliability.

Based on the above principle, another aspect of the embodiment of the present invention further provides a high-speed measurement method of fiber Bragg grating 01 signal based on double-edge filtering, as shown in FIG6 , the method specifically includes:

S1. Input a first optical signal of a first preset wavelength to a first port of the fiber Bragg grating 01, and input a second optical signal of a second preset wavelength to a second port of the fiber Bragg grating 01, wherein the first preset wavelength and the second preset wavelength are respectively:

λ ₁ =λ ₀ +Δλ (1)

λ ₂ =λ ₀ -Δλ (2)

Wherein, λ ₀ represents the initial center wavelength of the fiber grating 01, Δλ represents the preset wavelength difference, Δλ ₁ represents the first preset wavelength, and λ ₂ represents the second preset wavelength;

S2, collecting a first light intensity signal output from the first port of the fiber Bragg grating 01 and a second light intensity signal output from the second port, and calculating characteristic parameters of the fiber Bragg grating 01 based on the first light intensity signal and the second light intensity signal, the first light intensity signal is the sum of the reflected light intensity of the first light signal passing through the fiber Bragg grating 01 and the transmitted light intensity of the second light signal passing through the fiber Bragg grating 01, the second light intensity signal is the sum of the reflected light intensity of the second light signal passing through the fiber Bragg grating 01 and the transmitted light intensity of the first light signal passing through the fiber Bragg grating 01, and the calculation model of the characteristic parameters is:

Wherein, R represents the characteristic parameter, _P1 represents the first light intensity signal, and _P2 represents the second light intensity signal;

S3, obtaining a characteristic parameter curve of the fiber Bragg grating 01, and calculating the current central wavelength of the fiber Bragg grating 01 based on the characteristic parameter curve, wherein the characteristic parameter curve is a relationship curve between the central wavelength of the fiber Bragg grating 01 and the characteristic parameter.

The high-speed measurement method of the fiber Bragg grating 01 signal based on double-edge filtering provided in the embodiment of the present invention does not need to adjust the wavelength of the optical signal input to the fiber Bragg grating 01 during the formal measurement stage of the central wavelength of the fiber Bragg grating 01, thereby simplifying the measurement process, and the processing process of the measurement results is simple, without the need to process a large amount of spectral data, thereby improving the measurement speed.

It should be noted that the high-speed measurement method of the fiber Bragg grating 01 signal based on double-edge filtering provided in the embodiment of the present invention can be implemented by the high-speed measurement system of the fiber Bragg grating 01 signal based on double-edge filtering provided in the above embodiment, and can also be implemented by other systems that can perform the corresponding functions, and the present invention is not limited to this.

Furthermore, the high-speed measurement method of the fiber Bragg grating 01 signal based on double-edge filtering provided by the embodiment of the present invention also includes the process of determining the initial center wavelength and half-maximum full width of the fiber Bragg grating 01, and thus the method also includes:

S01, inputting an optical signal with a sequentially changing wavelength into the first port or the second port of the optical fiber Bragg grating 01, obtaining the reflected light intensity of the optical fiber Bragg grating 01 corresponding to the optical signals with different wavelengths, so as to collect a reflection spectrum curve of the optical fiber Bragg grating 01;

Specifically, when a tunable laser is used to scan the reflection spectrum of the fiber Bragg grating 01, the output wavelength of the laser is gradually adjusted to cover the entire wavelength range of the reflection spectrum of the fiber Bragg grating 01. In this process, the light waves emitted by the laser are sent into the fiber Bragg grating 01, and the fiber Bragg grating 01 reflects the light waves of a specific wavelength back, and these reflected light waves are detected and recorded. By recording the intensity of the reflected light at different wavelengths, the reflection spectrum of the fiber Bragg grating can be plotted.

S02, obtaining the initial central wavelength and half-maximum full width of the fiber Bragg grating 01 based on the reflection spectrum curve of the fiber Bragg grating 01;

S03, calculating the wavelength difference according to the half-width at half maximum of the fiber Bragg grating 01, the calculation formula is as follows:

Wherein, FWHM represents the full width at half maximum of the fiber Bragg grating 01.

The use of the half-width at half maximum of the fiber Bragg grating 01 to calculate the preset wavelength difference is a preferred embodiment of the present invention. In actual applications, the preset wavelength difference calculated by formula (4) may be different due to factors such as detection errors.

Furthermore, the high-speed measurement method of fiber Bragg grating 01 signal based on double-edge filtering provided by the embodiment of the present invention also includes a process of calibrating and fitting the characteristic parameter curve. Specifically, the method also includes:

S11, inputting a first optical signal of a first preset wavelength into a first port of the fiber Bragg grating 01, and inputting a second optical signal of a second preset wavelength into a second port of the fiber Bragg grating 01;

S12, controlling the fiber Bragg grating 01 to change the central wavelength to the target central wavelength, and obtaining a first light intensity signal output from the first port and a second light intensity signal output from the second port of the fiber Bragg grating 01;

It should be noted that, during the calibration process, the central wavelength of the fiber Bragg grating 01 can be changed by changing the external environmental characteristics of the fiber Bragg grating 01. Taking vibration as an example, by using a standard vibration table to apply different degrees of excitation to the fiber Bragg grating 01, the central wavelength of the fiber Bragg grating 01 is changed to determine the performance of the fiber Bragg grating at each point within the range and whether measurement can be achieved within the full range.

S13, calculating a characteristic parameter corresponding to the target central wavelength according to the first light intensity signal and the second light intensity signal corresponding to the target central wavelength;

S14, selecting a different target central wavelength and repeatedly performing the operations of step S12-step S13 to obtain a plurality of different groups of data sampling points, each group of data sampling points including a different target central wavelength and a characteristic parameter corresponding to the corresponding target central wavelength;

S15, fitting a relationship curve between the central wavelength of the fiber Bragg grating 01 and the characteristic parameter according to the multiple groups of different data sampling points to obtain the characteristic parameter curve.

It should be noted that, according to different accuracy requirements, different fitting forms can be used to fit the characteristic parameter curve.

Further, in a specific embodiment of the present invention, the central wavelength λ of the fiber Bragg grating 01 is composed of the initial central wavelength λ ₀ and the wavelength variation Δλ′, that is:

λ＝λ ₀ +Δλ' (5)

According to different requirements for measurement accuracy, different fitting methods can be used to fit the relationship between characteristic parameters and central wavelength. When the first-order polynomial fitting method is used, the relationship between characteristic parameters and central wavelength can be expressed as:

λ＝-0.1499R+λ ₀ (6)

At this time, the characteristic parameter curve is a straight line as shown in FIG5 . After data testing, the root mean square error RMSE at this time is 0.017307.

Of course, when a higher-precision calculation result is required, a higher-order polynomial fitting method can be used. When a ninth-order polynomial fitting method is used, the RMSE is only 0.00012.

Further, it can be seen from the accompanying drawings that in the embodiment of the present invention, sampling can be performed within the wavelength range of [λ ₀ -Δλ, λ ₀ +Δλ]. Therefore, controlling the fiber grating 01 to change the central wavelength to the target central wavelength includes: controlling the fiber grating 01 to change the central wavelength to the target central wavelength within the wavelength range of [λ ₀ -Δλ, λ ₀ +Δλ].

The high-speed measurement method of fiber Bragg grating 01 signal based on double-edge filtering proposed in the present invention can measure the signal at high speed after simple initial parameter measurement. Its maximum measurement speed depends only on the sampling speed of the photodiode, which can usually reach hundreds or even thousands of MHz.

For the method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the embodiments of the present invention are not limited by the order of the actions described, because according to the embodiments of the present invention, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily required by the embodiments of the present invention.

The high-speed measurement method and system of the fiber Bragg grating 01 signal based on double-edge filtering provided in this embodiment utilizes the bidirectional transmission characteristics of the optical fiber, and simultaneously inputs a first optical signal of a first preset wavelength and a second optical signal of a second preset wavelength at both ends of the fiber Bragg grating. In the measurement stage of the center wavelength of the fiber Bragg grating, it is not necessary to adjust the wavelength of the optical signal input to the fiber Bragg grating, which simplifies the measurement process and greatly improves the measurement speed. Moreover, the characteristic parameters calculated based on the first light intensity signal output from the first port and the second light intensity signal output from the second port only need to perform division and logarithm operations to calculate the current center wavelength of the fiber Bragg grating, so that the processing flow of the measurement results is simple, and there is no need to process a large amount of spectral data. The conversion of the characteristic parameters to the center wavelength of the fiber Bragg grating only needs to perform a few addition and multiplication operations according to the requirements for measurement accuracy, which puts less pressure on the computing device and can be deployed on edge devices with low computing power, further improving the measurement speed.

In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present invention and form different embodiments. For example, any one of the claimed embodiments may be used in any combination.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (5)

1. The method for measuring the fiber bragg grating signal at high speed based on double-edge filtering is characterized by comprising the following steps:

S1, inputting a first optical signal with a first preset wavelength at a first port of the fiber grating, and inputting a second optical signal with a second preset wavelength at a second port of the fiber grating, wherein the first preset wavelength and the second preset wavelength are respectively as follows:

λ₁＝λ₀+Δλ

λ₂＝λ₀-Δλ

wherein lambda ₀ represents the initial center wavelength of the fiber grating, delta lambda represents a preset wavelength difference value, lambda ₁ represents a first preset wavelength, and lambda ₂ represents a second preset wavelength;

S2, collecting a first light intensity signal output by a first port of the fiber grating and a second light intensity signal output by a second port of the fiber grating, calculating characteristic parameters of the fiber grating based on the first light intensity signal and the second light intensity signal, wherein the first light intensity signal is the sum of the reflected light intensity of the first light signal passing through the fiber grating and the transmitted light intensity of the second light signal passing through the fiber grating, the second light intensity signal is the sum of the reflected light intensity of the second light signal passing through the fiber grating and the transmitted light intensity of the first light signal passing through the fiber grating, and the calculation model of the characteristic parameters is as follows:

Or (b)

Wherein R represents a characteristic parameter, P ₁ represents a first light intensity signal, and P ₂ represents a second light intensity signal;

s3, acquiring a characteristic parameter curve of the fiber bragg grating, and calculating the current center wavelength of the fiber bragg grating based on the characteristic parameter curve, wherein the characteristic parameter curve is a relation curve of the center wavelength of the fiber bragg grating along with the characteristic parameter change: wherein,

The obtaining the characteristic parameter curve of the fiber bragg grating comprises the following steps:

S11, inputting a first optical signal with a first preset wavelength at a first port of the fiber grating, and inputting a second optical signal with a second preset wavelength at a second port of the fiber grating;

s12, controlling the fiber grating to change the central wavelength to the target central wavelength, and acquiring a first light intensity signal output by a first port and a second light intensity signal output by a second port of the fiber grating;

S13, calculating characteristic parameters corresponding to the target center wavelength according to the first light intensity signal and the second light intensity signal corresponding to the target center wavelength;

S14, selecting different target center wavelengths, and repeatedly executing the operations of the steps S12-S13 to obtain a plurality of groups of different data sampling points, wherein each group of data sampling points comprises different target center wavelengths and characteristic parameters corresponding to the corresponding target center wavelengths;

And S15, fitting a relation curve of the central wavelength of the fiber bragg grating along with the characteristic parameter change according to the plurality of groups of different data sampling points to obtain the characteristic parameter curve.

2. The method according to claim 1, characterized in that before performing step S1, the method further comprises:

Inputting optical signals with sequentially changed wavelengths into a first port or a second port of the fiber bragg grating, and obtaining the reflected light intensities of the fiber bragg grating corresponding to the optical signals with different wavelengths so as to acquire the reflection spectrum curve of the fiber bragg grating;

Acquiring initial center wavelength and full width at half maximum of the fiber bragg grating based on the reflection spectrum curve of the fiber bragg grating;

Calculating the wavelength difference according to the full width at half maximum of the fiber bragg grating, wherein the calculation formula is as follows:

wherein FWHM represents the full width at half maximum of the fiber grating.

3. The method of claim 2, wherein the target center wavelength has a wavelength range of [ lambda ₀-Δλ,λ₀ + delta lambda ].

4. A dual-edge filtering-based fiber bragg grating signal high-speed measurement system, the system comprising:

the first optical signal transmitting device is used for transmitting a first optical signal with a first preset wavelength, and the first preset wavelength is as follows:

λ₁＝λ₀+Δλ

Wherein lambda ₀ represents the initial center wavelength of the fiber grating, delta lambda represents a preset wavelength difference value, and lambda ₁ represents a first preset wavelength;

The first port of the first circulator is connected with the first optical signal transmitting device, and the second port of the first circulator is connected with the first port of the fiber bragg grating and is used for inputting the first optical signal to the first port of the fiber bragg grating;

the second optical signal transmitting device is used for transmitting a second optical signal with a second preset wavelength, and the second preset wavelength is as follows:

λ₂＝λ₀-Δλ

wherein λ ₂ represents a second preset wavelength;

The first port of the second circulator is connected with the second optical signal transmitting device, and the second port of the second circulator is connected with the second port of the fiber bragg grating and is used for inputting the second optical signal to the second port of the fiber bragg grating;

the first photoelectric conversion device is connected with the third port of the first circulator and is used for receiving reflected light of a first optical signal passing through the fiber bragg grating and transmitted light of a second optical signal passing through the fiber bragg grating through the first circulator and converting the optical signals into electric signals so as to obtain first light intensity signals;

The second photoelectric conversion device is connected with the third port of the second circulator and is used for receiving reflected light of a second optical signal passing through the fiber bragg grating and transmitted light of a first optical signal passing through the fiber bragg grating through the second circulator and converting the optical signal into an electric signal so as to obtain a second light intensity signal;

the demodulation processing equipment is used for receiving the first light intensity signal and the second light intensity signal, calculating the characteristic parameters of the fiber grating based on the first light intensity signal and the second light intensity signal, and the calculation model of the characteristic parameters R is as follows:

Or (b)

Wherein R represents a characteristic parameter, P ₁ represents a first light intensity signal, and P ₂ represents a second light intensity signal;

the demodulation processing equipment is also used for acquiring a characteristic parameter curve of the fiber grating and calculating the current center wavelength of the fiber grating based on the characteristic parameter curve, wherein the characteristic parameter curve is a relation curve of the center wavelength of the fiber grating along with the change of the characteristic parameter; wherein,

The obtaining the characteristic parameter curve of the fiber bragg grating comprises the following steps:

S11, inputting a first optical signal with a first preset wavelength at a first port of the fiber grating, and inputting a second optical signal with a second preset wavelength at a second port of the fiber grating;

s12, controlling the fiber grating to change the central wavelength to the target central wavelength, and acquiring a first light intensity signal output by a first port and a second light intensity signal output by a second port of the fiber grating;

S13, calculating characteristic parameters corresponding to the target center wavelength according to the first light intensity signal and the second light intensity signal corresponding to the target center wavelength;

S14, selecting different target center wavelengths, and repeatedly executing the operations of the steps S12-S13 to obtain a plurality of groups of different data sampling points, wherein each group of data sampling points comprises different target center wavelengths and characteristic parameters corresponding to the corresponding target center wavelengths;

And S15, fitting a relation curve of the central wavelength of the fiber bragg grating along with the characteristic parameter change according to the plurality of groups of different data sampling points to obtain the characteristic parameter curve.

5. The system of claim 4, wherein the first optical signal emitting device and the second optical signal emitting device are tunable laser emitters.