Wavelength deviation compensation method and system for rapid analysis of wavelength of far-end fiber grating

Abstract

A wavelength deviation compensation method for rapid analysis of the wavelength of a far-end fiber grating. The method comprises: emitting pulsed light into an optical fiber within a wavelength interval in a wavelength-stepped manner; obtaining the central wavelength and time delay data of each fiber grating on an entire optical fiber link, and a time delay value at the maximum wavelength on the link; and performing correction and compensation for a wavelength analysis result of the fiber grating. A time delay is obtained by means of step pulses, and the analyzed wavelength of a fiber grating is corrected and compensated for, thereby improving the accuracy of wavelength analysis. Further disclosed is a wavelength deviation compensation system for rapid analysis of the wavelength of a far-end fiber grating.

Description

Wavelength deviation compensation method and system for rapid resolution of remote fiber Bragg grating wavelength Technical Field

[0001] The present invention belongs to the field of optical fiber sensing, and in particular relates to a wavelength deviation compensation method and system for rapid wavelength resolution of a remote optical fiber grating. Background Art

[0002] In the fiber Bragg grating wavelength demodulation system of the scanning laser, when the fast scanning laser resolves the wavelength of the distant fiber Bragg grating sensor, the round-trip time of the light through the optical fiber will cause the detected distant fiber Bragg grating wavelength to be untrue and deviate from the actual wavelength. The higher the laser scanning rate and the farther the fiber Bragg grating is from the demodulation device, the greater the difference between the resolved wavelength and the actual wavelength.

[0003] Based on the above shortcomings, this proposal is proposed.

[0004] Summary of the Invention

[0005] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a wavelength deviation compensation method and system for rapid resolution of remote fiber Bragg grating wavelengths, which obtains time delay by stepping pulses, corrects and compensates the wavelength resolved by the fiber Bragg grating, and improves the accuracy of wavelength resolution.

[0006] Technical solution: To achieve the above purpose, the technical solution of the present invention is as follows:

[0007] A wavelength deviation compensation method for rapid resolution of far-end fiber Bragg grating wavelength, comprising:

[0008] Launching pulsed light into the optical fiber in a wavelength-stepping manner within a wavelength range;

[0009] Obtain the central wavelength and delay data of each fiber Bragg grating on the entire optical fiber link, as well as the time delay value at the maximum wavelength on the link;

[0010] Correction compensation is made to the results of fiber Bragg grating wavelength analysis.

[0011] Furthermore, the wavelength stepping method includes:

[0012] Setting a number of wavelength emission points within the wavelength range;

[0013] When emitting pulse light at each wavelength emission point, it lasts for a preset time width.

[0014] Furthermore, the time width is on the order of ns;

[0015] And / or, the time width is 5-10ns.

[0016] Furthermore, the wavelength step is no greater than the amplitude of the 3dB bandwidth of the fiber grating.

[0017] Furthermore, the wavelength of the wavelength emission point is set to λ m , the time point T of the maximum signal at wavelength m ,but:

[0018] λ m When the emitted pulse light is injected into the optical fiber, the m－1 ,λ m+1 The wavelength with the maximum signal is recorded at that time;

[0019] When T m =T m－1 =T m+1 When the central wavelength of the grating is determined to be λ m , that is, the central wavelength is λ m The time delay of the fiber Bragg grating leaving the demodulation device is T m .

[0020] Furthermore, the correction and compensation for the results of fiber Bragg grating wavelength analysis include:

[0021] In the wavelength range, the wavelength λ of each wavelength emission point is m The wavelength theoretically resolved at the demodulation end is recorded as the first resolution wavelength λ' m , the first analytical wavelength λ' m is the center wavelength λ m and wavelength deviation λ 偏差 The sum of m =λ m +λ 偏差 ;

[0022] Each of the first resolution wavelengths λ'm corresponds to the actual central wavelength λm of the fiber Bragg grating sensor and is used as the actual input value of the demodulation end for resolution to obtain the second resolution wavelength λ".

[0023] The absolute value of the difference between the first and second analytical wavelengths is compared with the minimum difference Δλ between adjacent wavelengths of the fiber grating sensor. If the absolute value of the difference is not greater than Δλ, the final output wavelength λ is the second analytical wavelength λ" minus the wavelength deviation λ. 偏差 , recorded as λ=λ"-λ 偏差 .

[0024] Furthermore, the starting end of the wavelength range is λs and the ending end is λe. When the wavelength of the laser changes from λs to λe within the time ΔT, the first resolution wavelength is:

[0025] λ' m =λ m +Tm ×(λe-λs) / ΔT;

[0026] Where T m ×(λe-λs) / ΔT is the wavelength deviation caused by time delay.

[0027] Furthermore, if the maximum central wavelength λp on the optical fiber link is close to λe, when the laser scans to the final wavelength λe, the semiconductor optical amplifier is turned off and the off time is kept as T p Then start the next round of laser scanning and turn off the semiconductor optical amplifier to maintain time, with the cycle time being ΔT+T p cycle.

[0028] Furthermore, a wavelength deviation compensation system for rapid resolution of remote fiber Bragg grating wavelength comprises:

[0029] Semiconductor scanning laser, used to generate wavelength-scanning laser;

[0030] a controller for controlling the semiconductor optical amplifier to be turned on or off to generate pulsed light and controlling the scanning of the wavelength of the semiconductor scanning laser;

[0031] A semiconductor optical amplifier receives instructions from a controller to generate pulsed laser light and turn on / off the scanning laser light injected into the optical fiber;

[0032] A data processor, used for time measurement and data processing;

[0033] Fiber Bragg grating sensor, connected in series to the optical fiber link.

[0034] Beneficial effect: The present invention realizes the detection of the time delay of each fiber Bragg grating sensor returning to the demodulation device end by means of a step pulse. The obtained time delay can be used to make a correct correction to the fiber Bragg grating wavelength resolution, thereby achieving the purpose of accurate measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic diagram of the overall process of the present invention;

[0036] FIG2 is a schematic diagram of the periodicity of the pulse wave emitted by the present invention;

[0037] FIG3 is a schematic diagram of the structure of the analysis system of the present invention. DETAILED DESCRIPTION

[0038] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0039] The terms used in this disclosure are for the purpose of describing particular embodiments only and are not intended to limit the disclosure. As used in this disclosure and the appended claims, the singular forms "a," "an," "the," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0040] The specific implementation of the present invention is further described in detail below with reference to the accompanying drawings and examples.

[0041] As shown in FIG1 , a wavelength deviation compensation method for rapid resolution of far-end fiber Bragg grating wavelength includes:

[0042] Pulsed light is emitted into the optical fiber in a wavelength-stepping manner within a wavelength range. The center wavelength and time delay data of each fiber Bragg grating (FBG) sensor along the entire optical fiber link, as well as the time delay value at the link's maximum wavelength, are obtained. Corrections are then made to the fiber Bragg grating wavelength resolution results. By using the pulse-stepping method, the time delay between each fiber Bragg grating sensor and the demodulation device is detected. The resulting time delay allows for correct corrections to the fiber Bragg grating wavelength resolution, achieving accurate measurement.

[0043] Among them, the wavelength stepping method includes: the wavelength step is not greater than the amplitude setting of the 3dB bandwidth of the fiber grating, and a number of wavelength emission points are set within the wavelength range; when emitting pulse light at each wavelength emission point, a semiconductor optical amplifier is used as an optical switch to control the continuous preset time width, and the time width is in the order of ns. Preferably, the time width is 5-10ns.

[0044] As shown in FIG2, the wavelength of the wavelength emission point is set to λ m , the time point T of the maximum signal at wavelength m , then: m When the emitted pulse light is injected into the optical fiber, the m－1 ,λ m+1 The wavelength with the maximum signal is recorded at the time; λ m－1 is λ m The wavelength of the last emission point corresponds to the time point of the maximum signal T m－1 ,λ m+1 is λ mThe wavelength of the next emission point corresponds to the time point of the maximum signal T m+1 ;

[0045] When T m =T m－1 =T m+1 When the central wavelength of the grating is determined to be λ m Nearby, so it is determined to be λ m , that is, the central wavelength is λ m The time delay of the fiber Bragg grating leaving the demodulation device is T m .

[0046] Correction and compensation for the results of fiber Bragg grating wavelength analysis include:

[0047] In the wavelength range, the wavelength λ of each wavelength emission point is m The wavelength theoretically resolved at the demodulation end is recorded as the first resolution wavelength λ' m , the first analytical wavelength λ' m is the center wavelength λm and the wavelength deviation λ 偏差 The sum of m =λ m +λ 偏差 ;

[0048] The starting end of the wavelength range is λs, and the ending end is λe. When the wavelength of the laser changes from λs to λe within the time ΔT, the first resolution wavelength is:

[0049] λ' m =λ m +T m ×(λe-λs) / ΔT;

[0050] Where T m ×(λe-λs) / ΔT is the wavelength deviation λ caused by time delay 偏差 .

[0051] Each of the first resolution wavelengths λ'm corresponds to the actual center wavelength λm of the fiber Bragg grating sensor and is analyzed as the actual input value of the demodulation end, that is, the wavelength value including the deviation value is used as the reference for analysis, thereby obtaining the second resolution wavelength λ".

[0052] The absolute value of the difference between the first and second analytical wavelengths is compared with the minimum difference Δλ between adjacent fiber Bragg grating sensor wavelengths. If the absolute value of the difference is not greater than Δλ, the final output wavelength is the second analytical wavelength minus the wavelength deviation, that is, λ = λ" - λ 偏差That is, when the central wavelength resolved by the demodulator is λ", if |λ"-λ'm|≤Δλ (Δλ is the minimum difference between adjacent wavelengths of the fiber Bragg grating sensor), then the final actual output wavelength should be λ"-Tm×(λe-λs) / ΔT.

[0053] By further emitting light pulses at each step from λs to λe, the center wavelength and delay data of each fiber Bragg grating on the entire optical fiber link are obtained, and the delay value Tp at the maximum wavelength on the link is found, and the corresponding center wavelength is λp.

[0054] If the maximum central wavelength λp on the optical fiber link is close to λe, when the laser scans to the final wavelength λe, the semiconductor optical amplifier is turned off and kept off for a time of T p Then start the next round of laser scanning and turn off the semiconductor optical amplifier to maintain time, with the cycle time being ΔT+T p The purpose is to solve the problem that the fiber Bragg grating cannot be measured near λe due to time delay.

[0055] A wavelength deviation compensation system for rapid wavelength resolution of a remote fiber Bragg grating (FBG) comprising:

[0056] Semiconductor scanning laser, used to generate wavelength-scanning laser;

[0057] A controller, controlling the on or off of the semiconductor optical amplifier to generate pulsed light and controlling the scanning of the wavelength of the semiconductor scanning laser;

[0058] A semiconductor optical amplifier receives instructions from a controller to generate pulsed laser light and turn on / off the scanning laser light injected into the optical fiber;

[0059] A data processor, used for time measurement and data processing;

[0060] Fiber Bragg grating sensor, connected in series to the optical fiber link.

[0061] It also includes a three-port optical circulator for connecting a photodetector, a semiconductor optical amplifier, and a fiber Bragg grating sensor.

[0062] It should be understood that although the terms "first," "second," and "third" may be used in this disclosure to describe various types of information, such information should not be limited to these terms. These terms are merely used to distinguish information of the same type from one another. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information.

[0063] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention.

[0064] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A wavelength deviation compensation method for rapid resolution of the wavelength of a distal fiber grating, characterized in that: Pulse light is emitted into the optical fiber in a wavelength-stepping manner within a wavelength range; The central wavelength and time delay data of each fiber grating on the entire optical fiber link are obtained, as well as the time delay value at the maximum wavelength on the link; The result of the wavelength resolution of the fiber grating is corrected and compensated.

2. A wavelength deviation compensation method for rapid analysis of the wavelength of a distal fiber grating according to claim 1, characterized in that: The wavelength-stepping manner includes: A number of wavelength emission points are set within the wavelength range; When emitting pulse light at each of the wavelength emission points, a preset time width is maintained.

3. A wavelength deviation compensation method for rapid resolution of the wavelength of a distal fiber grating according to claim 2, characterized in that: The time width is in the order of ns; And / or, the time width is 5 - 10 ns.

4. A wavelength deviation compensation method for rapid analysis of the wavelength of a distal fiber grating according to claim 1 or 2, characterized in that: The wavelength step is not greater than the amplitude of the 3dB bandwidth of the fiber grating.

5. A wavelength deviation compensation method for rapid analysis of the wavelength of a distal fiber grating according to claim 1, characterized in that: Set the wavelength of the wavelength emission point to λ m , the time point T of the maximum signal at the wavelength m , then: λ m When the emitted pulsed light is injected into the optical fiber, record the time for the wavelength λ m－1 and λ m+1 at which there is a maximum signal; When T m = T m－1 = T m+1 it is determined that the central wavelength of this grating is λ m , that is, the central wavelength is λ m and the time delay value of the fiber grating with the central wavelength of λ m .

6. A wavelength deviation compensation method for rapid analysis of the wavelength of a distal fiber grating according to claim 1, characterized in that: Correcting and compensating the result of the wavelength resolution of the fiber grating includes: Within the wavelength range, the wavelength λ of each wavelength emission point m The wavelength theoretically analyzed at the demodulation end is denoted as the first analyzed wavelength λ'm. The first analyzed wavelength λ'm is the sum of the central wavelength λm and the wavelength value deviation λ 偏差 , denoted as λ'm = λ m + λ 偏差 ; Each of the first resolved wavelengths λ'm is respectively corresponding to the actual central wavelength λm of the fiber grating sensor, and is used as the actual input value at the demodulation end for resolution to obtain the second resolved wavelength λ''; Compare the absolute value of the difference between the first analysis wavelength and the second analysis wavelength with the minimum difference Δλ adjacent to the wavelength of the fiber grating sensor. If the absolute value of the difference is not greater than Δλ, the finally output wavelength λ is the second analysis wavelength λ"minus the wavelength value deviation λ 偏差 , denoted as λ = λ" - λ 偏差 .

7. A wavelength deviation compensation method for rapid analysis of the wavelength of a distal fiber grating according to claim 6, characterized in that: The starting end of the wavelength range is λs, and the ending end is λe. When the wavelength of the laser changes from λs to λe within ΔT time, the first resolved wavelength is: λ'm = λm + Tm×(λe - λs) / ΔT; where Tm×(λe-λs) / ΔT is the wavelength value deviation λ caused by time delay 偏差 .

8. A wavelength deviation compensation method for rapid analysis of the wavelength of a distal fiber grating according to claims 1-7, characterized in that: If the maximum central wavelength λp on the optical fiber link is close to λe, when the laser scans to the last wavelength λe, the semiconductor optical amplifier is turned off, and after maintaining the off time for Tp, the next round of laser scanning and the off time of the semiconductor optical amplifier are maintained, and the cycle time is ΔT + Tp for cycling.

9. A wavelength deviation compensation system for rapid resolution of the wavelength of a remote fiber grating, characterized in that: It includes: A semiconductor scanning laser for generating wavelength-scanned laser light; A controller for controlling the turning on or off of the semiconductor optical amplifier to generate pulse light, and controlling the wavelength scanning of the semiconductor scanning laser; A semiconductor optical amplifier for receiving the instruction of the controller to generate pulsed laser light and turn on / off the scanned laser light injected into the optical fiber; A data processor for time measurement and data processing; A fiber grating sensor connected in series on the optical fiber link.

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