Wavelength deviation compensation method and system for fast resolution of remote fiber Bragg grating wavelength

Abstract

The present invention discloses a wavelength deviation compensation method for rapid resolution of far-end fiber Bragg grating wavelengths, including emitting pulse light into an optical fiber in a wavelength stepping manner within a wavelength interval; obtaining the central wavelength and time 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; and making corrections and compensations to the results of the fiber Bragg grating wavelength resolution. The time delay is obtained by stepping pulses, and the wavelength resolved by the fiber Bragg grating is corrected and compensated to improve the accuracy of the wavelength resolution.

Description

Technical Field

[0001] The invention belongs to the field of optical fiber sensing, and in particular relates to a wavelength deviation compensation method and system for rapid resolution of far-end optical fiber grating wavelength. 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 fiber Bragg grating sensor at the far end, the round-trip time of the light through the optical fiber will cause the detected wavelength of the distant fiber Bragg grating to be untrue and deviate from the real 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 real one.

[0003] Based on the above shortcomings, this solution is proposed. Summary of the invention

[0004] 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 a remote fiber Bragg grating wavelength, which obtains time delay by means of step pulses, corrects and compensates the wavelength resolved by the fiber Bragg grating, and improves the accuracy of wavelength resolution.

[0005] Technical solution: To achieve the above purpose, the technical solution of the present invention is as follows:

[0006] A wavelength deviation compensation method for rapid resolution of far-end fiber Bragg grating wavelength, comprising:

[0007] Launching pulsed light into the optical fiber in a wavelength stepping manner within a wavelength range;

[0008] Obtain the central wavelength and delay data of each fiber grating on the entire optical fiber link, as well as the time delay value at the maximum wavelength on the link;

[0009] Correction compensation is made to the results of fiber Bragg grating wavelength analysis.

[0010] Furthermore, the wavelength stepping method includes:

[0011] Setting a certain number of wavelength emission points within the wavelength range;

[0012] When emitting pulse light at each wavelength emission point, it lasts for a preset time width.

[0013] Furthermore, the time width is in the order of ns;

[0014] And / or, the time width is 5-10ns.

[0015] Furthermore, the wavelength step is not greater than the amplitude of the 3dB bandwidth of the fiber grating.

[0016] Furthermore, the wavelength of the wavelength emission point is set to λm, and the time point of the maximum signal at the wavelength is Tm, then:

[0017] When the pulse light emitted by λm is injected into the optical fiber, －1 ,λm +1 The wavelength with the maximum signal records the time;

[0018] When Tm=Tm －1 =Tm +1 When the central wavelength of the grating is determined to be λm, the time delay value of the fiber grating with a central wavelength of λm leaving the demodulation device is Tm.

[0019] Furthermore, the correction and compensation for the result of the fiber Bragg grating wavelength analysis includes:

[0020] In the wavelength range, the wavelength λm of each wavelength emission point is theoretically resolved at the demodulation end as the first resolved wavelength λ'm, which is the sum of the center wavelength λm and the wavelength value deviation λ 偏差 The sum of λ'm = λ m +λ 偏差 ;

[0021] Each of the first resolution wavelengths λ'm corresponds to the actual central wavelength λm of the fiber grating sensor and is analyzed as the actual input value of the demodulation end to obtain the second resolution wavelength λ".

[0022] The absolute value of the difference between the first resolution wavelength and the second resolution wavelength is compared with the minimum difference Δλ of the 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 resolution wavelength λ" minus the wavelength deviation λ 偏差 , recorded as λ=λ"-λ 偏差 .

[0023] Furthermore, the starting end of the wavelength interval 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:

[0024] λ'm=λm+Tm×(λe-λs) / ΔT;

[0025] Where Tm×(λe-λs) / ΔT is the wavelength deviation caused by time delay.

[0026] Furthermore, 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 the off time is maintained for Tp before the next round of laser scanning and the semiconductor optical amplifier is turned off for the holding time, with a cycle time of ΔT+Tp.

[0027] Furthermore, a wavelength deviation compensation system for rapid resolution of far-end fiber Bragg grating wavelength comprises:

[0028] Semiconductor scanning laser, used to generate wavelength scanning laser;

[0029] A controller, 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;

[0030] A semiconductor optical amplifier receives instructions from a controller to generate pulsed laser and turn on / off the scanning laser injected into the optical fiber;

[0031] A data processor, used for time measurement and data processing;

[0032] Fiber Bragg grating sensor, connected in series on the optical fiber link.

[0033] Beneficial effect: The present invention realizes the detection of the time delay of each fiber grating sensor returning to the demodulation device end by means of step pulse. Through the obtained time delay, the fiber grating wavelength analysis can be correctly corrected, thereby achieving the purpose of accurate measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Attached Figure 1 It is a schematic diagram of the overall process of the present invention;

[0035] Attached Figure 2 This is a schematic diagram of the periodicity of the pulse wave emitted by the present invention;

[0036] Attached Figure 3 It is a schematic diagram of the structure of the analysis system of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all 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.

[0038] The terms used in the present disclosure are for the purpose of describing specific embodiments only and are not intended to limit the present disclosure. The singular forms "a", "said" and "the" used in the present disclosure and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0039] The specific implementation of the present invention is further described in detail below in conjunction with the drawings and examples.

[0040] As attached Figure 1 As shown, a wavelength deviation compensation method for rapid resolution of far-end fiber Bragg grating wavelength includes:

[0041] Pulse light is emitted into the optical fiber in a wavelength stepping manner within a wavelength range; 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, are obtained; and corrections and compensations are made to the results of the fiber Bragg grating wavelength analysis. By means of step pulses, the time delay of each fiber Bragg grating sensor returning to the demodulation device end is detected. Through the obtained time delay, the fiber Bragg grating wavelength analysis can be correctly corrected, thereby achieving the purpose of accurate measurement.

[0042] 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 ns order. Preferably, the time width is 5-10ns.

[0043] As attached Figure 2 As shown, the wavelength of the wavelength emission point is set to λm, and the time point of the maximum signal at the wavelength is Tm. Then: when the pulse light emitted by λm is injected into the optical fiber, the effect on λm －1 ,λm +1 The wavelength with the maximum signal is recorded at the time; λm －1 is the wavelength of the last emission point on λm, and the corresponding time point of the maximum signal is Tm －1 ,λm +1 is the wavelength of the next emission point of λm, and the corresponding time point of the maximum signal is Tm +1 ;

[0044] When Tm=Tm －1 =Tm +1 When the central wavelength of the grating is determined to be near λm, it is determined to be λm, that is, the time delay value of the fiber grating with a central wavelength of λm leaving the demodulation device is Tm.

[0045] Corrections and compensations for the results of fiber Bragg grating wavelength analysis include:

[0046] In the wavelength range, the wavelength λm of each wavelength emission point is theoretically resolved at the demodulation end as the first resolved wavelength λ'm, which is the sum of the center wavelength λm and the wavelength value deviation λ 偏差 The sum of λ'm = λ m +λ 偏差 ;

[0047] The starting end of the wavelength interval 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:

[0048] λ'm=λm+Tm×(λe-λs) / ΔT;

[0049] Where Tm×(λe-λs) / ΔT is the wavelength deviation λ caused by time delay 偏差 .

[0050] Each of the first analytical wavelengths λ'm corresponds to the actual central 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 analyzed as a reference, so as to obtain the second analytical wavelength λ".

[0051] The absolute value of the difference between the first resolution wavelength and the second resolution wavelength is compared with the minimum difference Δλ of the adjacent wavelengths of the fiber grating sensor. If the absolute value of the difference is not greater than Δλ, the final output wavelength is the second resolution 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 grating sensor), then the final actual output wavelength should be λ"-Tm×(λe-λs) / ΔT.

[0052] By further emitting light pulses at each step from λs→λe, the central 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 central wavelength is λp.

[0053] If the maximum center 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 the off time is kept for Tp before the next round of laser scanning and the semiconductor optical amplifier is turned off for the holding time, with a cycle time of ΔT+Tp. The purpose is to solve the problem that the fiber Bragg grating near λe cannot be measured due to time delay.

[0054] A wavelength deviation compensation system for rapid resolution of remote fiber grating wavelength, comprising:

[0055] Semiconductor scanning laser, used to generate wavelength scanning laser;

[0056] A controller, 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;

[0057] A semiconductor optical amplifier receives instructions from a controller to generate pulsed laser and turn on / off the scanning laser injected into the optical fiber;

[0058] A data processor, used for time measurement and data processing;

[0059] Fiber Bragg grating sensor, connected in series on the optical fiber link.

[0060] It also includes a three-port optical circulator for connecting a photodetector, a semiconductor optical amplifier, and a fiber grating sensor.

[0061] It should be understood that although the terms first, second, third, etc. may be used in the present disclosure to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present disclosure, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information.

[0062] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the 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 orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0063] 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 principle 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 far-end fiber Bragg grating wavelength, characterized in that: Launching pulsed light into the optical fiber in a wavelength stepping manner within a wavelength range; Obtaining the central wavelength and time delay data of each fiber grating sensor on the entire optical fiber link, as well as the time delay value at the maximum wavelength on the link; Make corrections and compensations to the results of fiber Bragg grating wavelength analysis; Corrections and compensations for the results of fiber Bragg grating wavelength analysis include: In the wavelength range, the wavelength λ of each wavelength emission point m The wavelength theoretically resolved at the demodulation end is recorded as the first resolved 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 ; Each of the first analytical wavelengths λ' ｍ Corresponding to the actual central wavelength λ of the fiber Bragg grating sensor ｍ , and is analyzed as the actual input value of the demodulation end to obtain the second analytical wavelength λ"; The absolute value of the difference between the first resolution wavelength and the second resolution wavelength is compared with the minimum difference Δλ of the 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 resolution wavelength λ" minus the wavelength deviation λ 偏差 , recorded as λ=λ"-λ 偏差。 2. The wavelength deviation compensation method for rapid wavelength resolution of a remote fiber Bragg grating according to claim 1, characterized in that: The wavelength stepping method includes: Setting a plurality of wavelength emission points within the wavelength interval; When emitting pulse light at each wavelength emission point, it lasts for a preset time width.

3. The wavelength deviation compensation method for rapid wavelength resolution of a remote fiber Bragg grating according to claim 2, characterized in that: The time width is in the order of ns.

4. The wavelength deviation compensation method for rapid wavelength resolution of a remote fiber Bragg grating according to claim 2, characterized in that: The time width is 5-10ns.

5. A wavelength deviation compensation method for rapid resolution of far-end fiber Bragg grating wavelength according to claim 1 or 2, characterized in that: The wavelength step is no greater than the amplitude of the 3dB bandwidth of the fiber grating.

6. The wavelength deviation compensation method for rapid wavelength resolution of a remote fiber Bragg grating according to claim 1, characterized in that: Set the wavelength of the emission point to λ m The time point of the maximum signal at the wavelength is T m ,but: λ m When the emitted pulse light is injected into the optical fiber, m－1 , m＋1 The wavelength with the maximum signal records the time; When T m =T m－1 =T m＋1 When the central wavelength of this 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； λ m－1 is m The wavelength of the last emission point corresponds to the time point of the maximum signal T m－1 ,λ m＋1 is m The wavelength of the next emission point corresponds to the time point of the maximum signal T m＋1。 7. The wavelength deviation compensation method for rapid wavelength resolution of a remote fiber Bragg grating according to claim 1, characterized in that: The starting point of the wavelength range is λ ｓ , the termination end is λ ｅ , when the laser wavelength changes from λ ｓ To ｅ In the process, the first analytical wavelength is: λ' ｍ =λ ｍ ++D ｍ ×(λ) ｅ -l ｓ ) / ΔT; Where T ｍ ×(λ ｅ -λ ｓ ) / ΔT is the wavelength deviation λ caused by time delay 偏差 .

8. The wavelength deviation compensation method for rapid wavelength resolution of a remote fiber Bragg grating according to claim 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 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 the time, with the cycle time as ΔT+T p cycle.

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