A heterogeneous grating array and distributed multi-parameter sensing system

Abstract

The present invention provides a heterogeneous parallel-band grating array and a distributed multi-parameter sensing system, which belong to the field of optical fiber sensing technology. The heterogeneous parallel-band grating array includes: a prestressed grating array and a relaxed grating array, the prestressed grating array includes a first optical fiber and a plurality of prestressed broadband gratings and a plurality of prestressed narrowband gratings inscribed on the first optical fiber, and the relaxed grating array includes a second optical fiber and a plurality of relaxed broadband gratings and a plurality of relaxed narrowband gratings inscribed on the second optical fiber. The present invention obtains wavelength drift and quasi-static strain by jointly solving the prestressed grating array and the relaxed grating array, that is, it can realize the measurement of temperature and quasi-static strain. Vibration measurement is realized by using prestressed broadband gratings or relaxed broadband gratings, that is, it realizes the three-parameter measurement of a single optical cable, thereby improving the application prospects of the heterogeneous parallel-band grating array.

Description

Technical Field

[0001] The present invention relates to the field of grating sensing technology, and in particular to a heterogeneous and multi-parameter grating array and a distributed multi-parameter sensing system. Background Art

[0002] Distributed fiber optic sensing technology, utilizing the optical fiber itself as a sensor, enables continuous, distributed monitoring of environmental parameters within the area covered by the fiber. Combining sensing and transmission functions, it can obtain information on the spatial and temporal multidimensional distribution of physical quantities. Distributed fiber optic sensing primarily exploits three different scattering mechanisms within optical fibers: Rayleigh scattering, Raman scattering, and Brillouin scattering. The intensity and phase of Rayleigh scattered light are highly sensitive to external vibrations, leading to the development of distributed vibration sensing systems based on Rayleigh scattering intensity and phase demodulation. Stokes light from Raman scattering is only sensitive to temperature, while Stokes light is insensitive to temperature. This has led to the development of distributed temperature sensing systems based on Raman scattering. Brillouin scattering is sensitive to both temperature and strain, and the Brillouin frequency shift exhibits a linear relationship with changes in temperature and strain. This has led to the development of distributed strain sensing systems based on Brillouin scattering.

[0003] However, traditional distributed fiber optic sensing technology utilizes only a single scattering mechanism, resulting in a limited range of measurable parameters. In many cases, a single parameter cannot provide sufficient information about the measurement, leading to misjudgments and false alarms, which adversely impact modern industrial applications. In contrast, multi-parameter measurement provides more valuable information for effectively identifying fault events. Although multiple distributed fiber optic sensing devices can be deployed in field tests to obtain multi-parameter information, this significantly increases costs. Furthermore, the use of multiple separate devices occupies multiple optical fibers, making multi-parameter measurement impossible in scenarios with strict space requirements.

[0004] Therefore, there is an urgent need to provide a heterogeneous grating array and a distributed multi-parameter sensing system to realize single-fiber cable multi-parameter measurement and improve the application prospects of grating arrays. Summary of the Invention

[0005] In view of this, it is necessary to provide a heterogeneous grating array and a distributed multi-parameter sensing system to solve the technical problem in the existing technology that a single optical cable cannot measure multiple parameters.

[0006] On the one hand, in order to solve the above technical problems, the present invention provides a heterogeneous banded grating array, including a prestressed grating array and a relaxed grating array, wherein the prestressed grating array includes a first optical fiber and a plurality of prestressed broadband gratings and a plurality of prestressed narrowband gratings inscribed on the first optical fiber, and the relaxed grating array includes a second optical fiber and a plurality of relaxed broadband gratings and a plurality of relaxed narrowband gratings inscribed on the second optical fiber.

[0007] In a possible implementation, the plurality of prestressed narrowband gratings and the plurality of relaxed narrowband gratings constitute a plurality of narrowband grating pairs, and each narrowband grating pair includes a prestressed narrowband grating and a relaxed narrowband grating.

[0008] In a possible implementation, the plurality of prestressed broadband gratings and the plurality of prestressed narrowband gratings are staggered and equidistantly written, and the plurality of relaxed broadband gratings and the plurality of relaxed narrowband gratings are staggered and equidistantly written.

[0009] In a possible implementation, the 3dB bandwidth of the prestressed broadband grating and the relaxed broadband grating is 1548.71nm~1552.99nm, and the central wavelength of the prestressed narrowband grating and the relaxed narrowband grating is 1550.79nm.

[0010] On the other hand, the present invention also provides a distributed multi-parameter sensing system, including an optical signal generation module, a heterogeneous parallel grating array, and a signal processing module;

[0011] The optical signal generating module is used to generate a first tunable pulse light, a second tunable pulse light and a continuous intrinsic light;

[0012] The heterogeneous parallel-band grating array is used to generate a first reflected pulse light signal and a second reflected pulse light signal based on the first tunable pulse light and the second tunable pulse light;

[0013] The signal processing module is used to perform signal processing on the first reflected pulse light signal, the second reflected pulse light signal and the continuous intrinsic light to obtain vibration measurement results, temperature measurement results and quasi-static strain measurement results;

[0014] The heterogeneous parallel-band grating array is the heterogeneous parallel-band grating array described in any one of the possible implementations above.

[0015] In one possible implementation, the optical signal generation module includes a tunable laser, a first fiber coupler, an acousto-optic modulator, a second fiber coupler, a first circulator, and a second circulator;

[0016] The tunable laser is used to generate continuous frequency-sweep light and multiple trigger signals in a stepping mode;

[0017] The first optical fiber coupler is used to divide the continuous frequency sweep light into intrinsic light and measurement light;

[0018] The acousto-optic modulator is used to perform chopping processing on the measurement light in response to the trigger signal to generate an initial tunable pulse light;

[0019] The second optical fiber coupler is used to divide the initial tunable pulse light to generate the first tunable pulse light and the second tunable pulse light;

[0020] The first circulator is used to input the first tunable pulse light into the relaxed grating array;

[0021] The second circulator is used to input the second tunable pulse light into the prestressed grating array.

[0022] In a possible implementation, the optical signal generation module further includes a first amplifier provided between the second optical fiber coupler and the first circulator, and a second amplifier provided between the second optical fiber coupler and the second circulator;

[0023] The first amplifier is used to amplify the first tunable pulse light;

[0024] The second amplifier is used to amplify the second tunable pulse light.

[0025] In a possible implementation, the signal processing module includes a first photodetector, a third optical fiber coupler, a second photodetector, a balanced photodetector, and a data acquisition card;

[0026] The first photodetector is used to convert the first reflected pulse light signal into a first reflected pulse electrical signal;

[0027] The third optical fiber coupler is used to divide the second reflected pulse optical signal into a first sub-optical signal and a second sub-optical signal;

[0028] The second photodetector is used to convert the first sub-light signal into a first electrical signal;

[0029] The balanced photodetector is used to perform coherent beat frequency processing on the second sub-light signal and the continuous intrinsic light to generate a beat frequency signal, and perform signal conversion to generate a second electrical signal;

[0030] The data acquisition card is used to generate a temperature measurement result based on the first reflected pulse electrical signal, generate a quasi-static strain measurement result based on the first reflected pulse electrical signal and the first electrical signal, and generate a vibration measurement result based on the second electrical signal.

[0031] In a possible implementation, the distributed multi-parameter sensing system further includes a signal energy determination module, wherein the signal energy determination module is disposed between the heterogeneous parallel-band grating array and the signal processing module;

[0032] The signal energy determination module is configured to determine a first signal energy value of the first reflected pulsed optical signal and a second signal energy value of the second reflected pulsed optical signal, and determine a first narrowband optical signal and a first broadband optical signal in the first reflected pulsed optical signal based on the first signal energy value and an energy threshold, and determine a second narrowband optical signal and a second broadband optical signal in the second reflected pulsed optical signal based on the second signal energy value and the energy threshold;

[0033] The first photodetector is used to receive the first narrowband optical signal, the second photodetector is used to receive the second narrowband optical signal, and the balanced photodetector is used to receive the second broadband optical signal.

[0034] In a possible implementation, the data acquisition card is further configured to receive the multiple trigger signals, and generate temperature measurement results, vibration measurement results, and quasi-static strain measurement results based on the multiple trigger signals.

[0035] The beneficial effects of the present invention are as follows: the heterogeneous parallel-band grating array provided by the present invention, by configuring it to include a prestressed grating array and a relaxed grating array, since the wavelength drift of the relaxed grating array is only affected by temperature, while the wavelength drift of the prestressed grating array is affected by both temperature and quasi-static strain, the wavelength drift and quasi-static strain can be obtained by jointly solving the prestressed grating array and the relaxed grating array, that is, the measurement of temperature and quasi-static strain can be achieved. Furthermore, by configuring the prestressed grating array to include a prestressed broadband grating and the relaxed grating array to include a relaxed broadband grating, vibration measurement can be achieved based on the prestressed broadband grating or the relaxed broadband grating, that is, three-parameter measurement of a single optical cable is achieved, thereby improving the application prospects of the heterogeneous parallel-band grating array. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 A schematic structural diagram of an embodiment of a heterogeneous parallel grating array provided by the present invention;

[0038] Figure 2 A schematic structural diagram of an embodiment of the distributed multi-parameter sensing system provided by the present invention;

[0039] Figure 3 A schematic structural diagram of a specific embodiment of the distributed multi-parameter sensing system provided by the present invention;

[0040] Figure 4 A schematic diagram of the vibration coherence detection beat frequency results provided by the present invention;

[0041] Figure 5 This is a spectrum diagram obtained by the data acquisition card provided by the present invention. DETAILED DESCRIPTION

[0042] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0043] It should be understood that the schematic drawings are not drawn to scale. The flowcharts used in the present invention illustrate operations implemented according to some embodiments of the present invention. It should be understood that the operations of the flowcharts can be implemented out of sequence, and steps that have no logical contextual relationship can be reversed in order or implemented simultaneously. In addition, those skilled in the art, guided by the content of the present invention, can add one or more other operations to the flowcharts or remove one or more operations from the flowcharts. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in the form of software, or in one or more hardware modules or integrated circuits, or in different networks and / or processor systems and / or microcontroller systems.

[0044] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute a separate or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0045] The present invention provides a heterogeneous parallel grating array and a distributed multi-parameter sensing system, which are described below respectively.

[0046] Figure 1 A schematic structural diagram of an embodiment of a heterogeneous and multi-band grating array provided by the present invention is shown in FIG. Figure 1As shown, the heterogeneous banded grating array 100 includes: a prestressed grating array 110 and a relaxed grating array 120, the prestressed grating array 110 includes a first optical fiber 111 and a plurality of prestressed broadband gratings 112 and a plurality of prestressed narrowband gratings 113 inscribed on the first optical fiber 111, and the relaxed grating array 120 includes a second optical fiber 121 and a plurality of relaxed broadband gratings 122 and a plurality of relaxed narrowband gratings 123 inscribed on the second optical fiber 121.

[0047] The first optical fiber 111 and the second optical fiber 121 are both single-mode optical fibers.

[0048] The relaxed narrowband grating 123 is used to measure temperature, the prestressed narrowband grating 113 and the relaxed narrowband grating 123 are used together to measure quasi-static strain, and the prestressed broadband grating 112 or the relaxed broadband grating 122 is used to measure vibration.

[0049] Compared to the prior art, the heterogeneous parallel-band grating array 100 provided in an embodiment of the present invention includes a prestressed grating array 110 and a relaxed grating array 120. Since the wavelength drift of the relaxed grating array 120 is only affected by temperature, while the wavelength drift of the prestressed grating array 110 is affected by both temperature and quasi-static strain, the wavelength drift and quasi-static strain can be obtained by jointly solving the prestressed grating array 110 and the relaxed grating array 120, that is, the measurement of temperature and quasi-static strain can be achieved. Furthermore, by configuring the prestressed grating array 110 to include a prestressed broadband grating 112 and the relaxed grating array 120 to include a relaxed broadband grating 122, vibration measurement can be achieved based on the prestressed broadband grating 112 or the relaxed broadband grating 122, that is, three-parameter measurement of a single optical cable is achieved, thereby improving the application prospects of the heterogeneous parallel-band grating array 100.

[0050] Since the quasi-static strain can only be determined by the cooperation of the prestressed narrowband grating 113 and the relaxed narrowband grating 123, in order to achieve the measurement of the quasi-static strain of each detection point, in some embodiments of the present invention, multiple prestressed narrowband gratings 113 and multiple relaxed narrowband gratings 123 form multiple narrowband grating pairs, and each narrowband grating pair includes a prestressed narrowband grating 113 and a relaxed narrowband grating 123.

[0051] In the embodiment of the present invention, by arranging each prestressed narrowband grating 113 to have a corresponding relaxed narrowband grating 123 , quasi-static strain measurement of each detection point can be achieved.

[0052] To achieve full-field measurement of parameters, in some embodiments of the present invention, multiple prestressed broadband gratings 112 and multiple prestressed narrowband gratings 113 are staggered and equidistantly written, and multiple relaxed broadband gratings 122 and multiple relaxed narrowband gratings 123 are staggered and equidistantly written.

[0053] By staggering the writing of multiple prestressed broadband gratings 112 and multiple prestressed narrowband gratings 113, and staggering the writing of multiple relaxed broadband gratings 122 and multiple relaxed narrowband gratings 123, parameter measurement can be achieved over the entire range of the prestressed grating array 110 and the relaxed grating array 120. Furthermore, by staggering the writing of multiple prestressed broadband gratings 112 and multiple prestressed narrowband gratings 113 at equal intervals, the heterogeneous parallel-band grating array 100 can be fabricated by simply using an existing mask for writing, thereby reducing the difficulty of fabrication.

[0054] In a specific embodiment of the present invention, the 3dB bandwidth of the prestressed broadband grating 112 and the relaxed broadband grating 122 is 1548.71nm-1552.99nm, and the central wavelength of the prestressed narrowband grating 113 and the relaxed narrowband grating 123 is 1550.79nm.

[0055] In order to realize the practical application of heterogeneous and parallel grating arrays, the present invention also provides a distributed multi-parameter sensing system, such as Figure 2 As shown, the distributed multi-parameter sensing system 10 includes: an optical signal generating module 200, a heterogeneous and parallel grating array 100, and a signal processing module 300;

[0056] The optical signal generating module 200 is used to generate a first tunable pulse light, a second tunable pulse light and a continuous intrinsic light;

[0057] The heterogeneous parallel-band grating array 100 is used to generate a first reflected pulse light signal and a second reflected pulse light signal based on a first tunable pulse light and a second tunable pulse light;

[0058] The signal processing module 300 is used to perform signal processing on the first reflected pulse light signal, the second reflected pulse light signal, and the continuous intrinsic light to obtain vibration measurement results, temperature measurement results, and quasi-static strain measurement results;

[0059] The heterogeneous parallel-band grating array is the heterogeneous parallel-band grating array in any one of the above embodiments.

[0060] In the embodiment of the present invention, an optical signal generation module 200 is provided to provide a tunable pulse optical sequence for the heterogeneous parallel-belt grating array 100, and a signal processing module 300 is provided to process the reflected pulse optical signal generated by the heterogeneous parallel-belt grating array 100, thereby obtaining vibration measurement results and temperature measurement results, thereby realizing the practical measurement application of the heterogeneous parallel-belt grating array 100.

[0061] In existing technologies, the demodulation process for multi-parameter physical quantities typically involves assigning corresponding light sources to the multiple grating arrays measuring the multiple parameters. Distributed multi-parameter sensing systems based on weak grating arrays typically require a dual-light source optical path: a narrow-linewidth laser source for phase demodulation of dynamic vibrations, and a tunable or broadband light source for wavelength demodulation of temperature or strain. This dual-light source optical path presents the following technical issues: 1. The sensing system structure is complex and has low integration; 2. Synchronicity between the two light sources cannot be guaranteed, resulting in unreliable measurement results.

[0062] In order to solve the above technical problems, in some embodiments of the present invention, Figure 3 As shown, the optical signal generating module 200 includes: a tunable laser 210, a first fiber coupler 220, an acousto-optic modulator 230, a second fiber coupler 240, a first circulator 250 and a second circulator 260;

[0063] The tunable laser 210 is used to generate continuous frequency sweep light and multiple trigger signals in a stepping mode;

[0064] The first fiber coupler 220 is used to divide the continuous frequency sweep light into the intrinsic light and the measurement light;

[0065] The acousto-optic modulator 230 is used to chop the measurement light in response to the trigger signal to generate an initial tunable pulse light;

[0066] The second fiber coupler 240 is used to split the initial tunable pulse light to generate a first tunable pulse light and a second tunable pulse light;

[0067] The first circulator 250 is used to input the first tunable pulse light into the relaxed grating array;

[0068] The second circulator 260 is used to input the second tunable pulse light into the pre-stressed grating array.

[0069] Specifically, the wavelength scanning range of the tunable laser 210 is 1549-1552 nm, and the scanning step length is 1 GHz.

[0070] The embodiment of the present invention processes and divides the continuous frequency-sweeping light generated by the tunable laser 210 to generate a first tunable pulse light and a second tunable pulse light, which are used to measure temperature, quasi-static strain, and vibration, respectively. This realizes single-light-source multi-parameter measurement, improves the integration of the distributed multi-parameter sensing system 10, and ensures the synchronization of the first tunable pulse light and the second tunable pulse light, thereby improving the reliability of the temperature, quasi-static strain, and vibration measurement results.

[0071] It should be noted that the initial tunable pulse light generated by the acousto-optic modulator 230 is a pulse sequence, including a plurality of pulse signals with different frequencies, and the frequency differences between adjacent pulse signals are the same.

[0072] In the embodiment of the present invention, by setting the initial tunable pulse light to be a pulse sequence, wavelength division and frequency division multiplexing can be achieved, and the measurement accuracy and measurement range of the distributed multi-parameter sensing system 10 can be further improved.

[0073] In order to improve the signal strength of the first tunable pulse light and the second tunable pulse light, and to further improve the accuracy and precision of the measurement results, in some embodiments of the present invention, as Figure 3 As shown, the optical signal generating module 200 further includes a first amplifier 270 disposed between the second fiber coupler 240 and the first circulator 250 and a second amplifier 280 disposed between the second fiber coupler 240 and the second circulator 260;

[0074] The first amplifier 270 is used to amplify the first tunable pulse light;

[0075] The second amplifier 280 is used to amplify the second tunable pulse light.

[0076] In the embodiment of the present invention, by providing a first amplifier 270 and a second amplifier 280 to amplify the first tunable pulse light and the second tunable pulse light respectively, the signal strength of the first tunable pulse light and the second tunable pulse light can be improved, thereby further improving the measurement precision and accuracy of temperature, quasi-static strain and vibration measurement.

[0077] Specifically, the first amplifier 270 and the second amplifier 280 are both erbium-doped fiber amplifiers.

[0078] In some embodiments of the present invention, Figure 3 As shown, the signal processing module 300 includes: a first photodetector 310, a third fiber coupler 320, a second photodetector 330, a balanced photodetector 340 and a data acquisition card 350;

[0079] The first photodetector 310 is used to convert the first reflected pulse optical signal into a first reflected pulse electrical signal;

[0080] The third optical fiber coupler 320 is used to divide the second reflected pulse optical signal into a first sub-optical signal and a second sub-optical signal;

[0081] The second photodetector 330 is used to convert the first sub-optical signal into a first electrical signal;

[0082] The balanced photodetector 340 is used to perform coherent beat frequency processing on the second light sub-signal and the continuous intrinsic light to generate a beat frequency signal, and perform signal conversion to generate a second electrical signal;

[0083] The data acquisition card 350 is used to generate a temperature measurement result based on the first reflected pulse electrical signal, generate a quasi-static strain measurement result based on the first reflected pulse electrical signal and the first electrical signal, and generate a vibration measurement result based on the second electrical signal.

[0084] In the embodiment of the present invention, continuous intrinsic light is input into the balanced photodetector 340 , and a coherent beat signal is obtained based on the second light sub-signal and the continuous intrinsic light, thereby achieving vibration demodulation.

[0085] It should be noted that the embodiment of the present invention does not need to use a phase compensation algorithm when performing phase demodulation to obtain vibration measurement results. This is because: the phase difference values ​​obtained by demodulating different wavelengths are different. When the wavelength scanning range of the tunable laser 210 is 1549nm~1552nm, the phase synthesis error σ syn The maximum value is the deviation between the phase difference corresponding to a wavelength of 1549 nm and the phase difference corresponding to a wavelength of 1552 nm, as shown in the following formula:

[0086]

[0087] The maximum phase synthesis error is less than 0.2%, which is negligible. Therefore, the phase compensation algorithm is not used, and the phase differences at different wavelengths are directly spliced. The specific phase value solution algorithm is the same as the traditional heterodyne coherent detection demodulation algorithm. After denoising through a low-pass filter, the final dynamic vibration information can be obtained. The details are not described here.

[0088] Since the broadband and narrowband gratings overlap in bandwidth, the following results will occur: for a wavelength of 1549 nm, only the broadband grating has a reflection signal, so all beat frequency waveforms can be used for dynamic vibration demodulation; for a wavelength of 1550.12 nm, both the broadband and narrowband gratings have reflection signals, and only half of the beat frequency waveforms can be used for dynamic vibration demodulation. Therefore, it is necessary to automatically screen out the signals of the corresponding broadband gratings suitable for dynamic vibration demodulation.

[0089] Therefore, in order to ensure the accuracy of temperature, vibration, and quasi-static strain measurement results, in some embodiments of the present invention, Figure 2 As shown, the distributed multi-parameter sensing system 10 further includes a signal energy determination module 400 , which is disposed between the heterogeneous parallel-band grating array 100 and the signal processing module 300 ;

[0090] The signal energy determination module 400 is used to determine a first signal energy value of the first reflected pulse light signal and a second signal energy value of the second reflected pulse light signal, and to determine a first narrowband light signal and a first broadband light signal in the first reflected pulse light signal based on the first signal energy value and an energy threshold, and to determine a second narrowband light signal and a second broadband light signal in the second reflected pulse light signal based on the second signal energy value and the energy threshold.

[0091] The first photodetector 310 is used to receive the first narrowband optical signal, the second photodetector 330 is used to receive the second narrowband optical signal, and the balanced photodetector 340 is used to receive the second broadband optical signal.

[0092] It should be understood that: since the reflection intensity of the central wavelength of the narrowband grating is much higher than that of the broadband grating, the envelope amplitude of its coherent beat signal is also stronger than the beat signal corresponding to the broadband grating, such as Figure 4 As shown, the initial wavelength state of the tunable laser 210 can be set to 1550.79 nm for single wavelength scanning. After all beat signals are enveloped, beat signals above or equal to the energy threshold are signals corresponding to the narrowband grating, and beat signals below the energy threshold are signals corresponding to the broadband grating.

[0093] Because the tunable laser generates continuously swept light in a stepping mode, each sweep light has a different wavelength. Therefore, data acquisition card 350 needs to splice the signals of multiple wavelengths to obtain an overall spectral signal. To ensure reliable and accurate splicing, in some embodiments of the present invention, data acquisition card 350 is also configured to receive the multiple trigger signals and generate temperature, vibration, and quasi-static strain measurement results based on the multiple trigger signals.

[0094] In addition to obtaining the first reflected pulse electrical signal, the first electrical signal, and the second electrical signal, the data acquisition card 350 in the embodiment of the present invention also obtains multiple trigger signals. The multiple trigger signals represent the number of wavelength changes. Based on the multiple trigger signals, signal splicing of different wavelengths can be achieved, providing a splicing reference for vibration, temperature, and quasi-static strain measurement results, thereby improving the accuracy of vibration, temperature, and quasi-static strain measurement results.

[0095] In a specific embodiment of the present invention, Figure 5 As shown, Figure 5 (a) is the result of a single relaxed broadband grating and a single relaxed narrowband grating after being collected and spliced ​​by a data acquisition card. Figure 5 (b) is the total reflection spectrum result after all grating reflection signals are collected and spliced ​​by the data acquisition card.

[0096] In summary, the distributed multi-parameter sensing system provided by the embodiment of the present invention can realize distributed multi-parameter sensing through a single light source through a single light source optical path, and only three channels are required for detection, which greatly reduces the overall complexity and hardware cost of the distributed multi-parameter sensing system. At the same time, the detection light of different channels is separated by a fiber coupler, which avoids the accumulation of detection errors caused by long-term continuous switching of the optical switch. Furthermore, the temperature and quasi-static strain are measured based on the heterogeneous grating array, and the wavelength demodulation scheme of the center wavelength peak is used. Compared with the calculation of the overall spectral drift based on the cross-correlation of the chirped grating, the real-time performance and calculation efficiency are higher. For vibration measurement, the upper limit of the theoretical frequency response range of the system is improved due to the use of a single light source instead of a dual light source equidistant pulse combination sequence.

[0097] The above is a detailed introduction to a heterogeneous grating array and a distributed multi-parameter sensing system provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the ideas of the present invention, there may be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A heterogeneous banded grating array, characterized in that: The invention comprises a prestressed grating array and a relaxed grating array, wherein the prestressed grating array comprises a first optical fiber and a plurality of prestressed broadband gratings and a plurality of prestressed narrowband gratings inscribed on the first optical fiber, and the relaxed grating array comprises a second optical fiber and a plurality of relaxed broadband gratings and a plurality of relaxed narrowband gratings inscribed on the second optical fiber.

2. The heterogeneous banded grating array according to claim 1, wherein: The plurality of prestressed narrowband gratings and the plurality of relaxed narrowband gratings constitute a plurality of narrowband grating pairs, and each narrowband grating pair includes a prestressed narrowband grating and a relaxed narrowband grating.

3. The heterogeneous banded grating array according to claim 1, wherein: The plurality of prestressed broadband gratings and the plurality of prestressed narrowband gratings are staggered and equidistantly written, and the plurality of relaxed broadband gratings and the plurality of relaxed narrowband gratings are staggered and equidistantly written.

4. The heterogeneous banded grating array according to claim 1, wherein: The 3dB bandwidth of the prestressed broadband grating and the relaxed broadband grating is 1548.71nm~1552.99nm, and the central wavelength of the prestressed narrowband grating and the relaxed narrowband grating is 1550.79nm.

5. A distributed multi-parameter sensing system, characterized in that: It includes an optical signal generation module, a heterogeneous parallel grating array, and a signal processing module; The optical signal generating module is used to generate a first tunable pulse light, a second tunable pulse light and a continuous intrinsic light; The heterogeneous parallel-band grating array is used to generate a first reflected pulse light signal and a second reflected pulse light signal based on the first tunable pulse light and the second tunable pulse light; The signal processing module is used to perform signal processing on the first reflected pulse light signal, the second reflected pulse light signal and the continuous intrinsic light to obtain vibration measurement results, temperature measurement results and quasi-static strain measurement results; Wherein, the heterogeneous parallel-band grating array is the heterogeneous parallel-band grating array described in any one of claims 1-4.

6. The distributed multi-parameter sensing system according to claim 5, characterized in that: The optical signal generation module includes a tunable laser, a first fiber coupler, an acousto-optic modulator, a second fiber coupler, a first circulator, and a second circulator; The tunable laser is used to generate continuous frequency-sweep light and multiple trigger signals in a stepping mode; The first optical fiber coupler is used to divide the continuous frequency sweep light into intrinsic light and measurement light; The acousto-optic modulator is used to perform chopping processing on the measurement light in response to the trigger signal to generate an initial tunable pulse light; The second optical fiber coupler is used to divide the initial tunable pulse light to generate the first tunable pulse light and the second tunable pulse light; The first circulator is used to input the first tunable pulse light into the relaxed grating array; The second circulator is used to input the second tunable pulse light into the prestressed grating array.

7. The distributed multi-parameter sensing system according to claim 6, characterized in that: The optical signal generating module further includes a first amplifier disposed between the second optical fiber coupler and the first circulator and a second amplifier disposed between the second optical fiber coupler and the second circulator; The first amplifier is used to amplify the first tunable pulse light; The second amplifier is used to amplify the second tunable pulse light.

8. The distributed multi-parameter sensing system according to claim 7, characterized in that: The signal processing module includes a first photodetector, a third optical fiber coupler, a second photodetector, a balanced photodetector and a data acquisition card; The first photodetector is used to convert the first reflected pulse light signal into a first reflected pulse electrical signal; The third optical fiber coupler is used to divide the second reflected pulse optical signal into a first sub-optical signal and a second sub-optical signal; The second photodetector is used to convert the first sub-light signal into a first electrical signal; The balanced photodetector is used to perform coherent beat frequency processing on the second sub-light signal and the continuous intrinsic light to generate a beat frequency signal, and perform signal conversion to generate a second electrical signal; The data acquisition card is used to generate a temperature measurement result based on the first reflected pulse electrical signal, generate a quasi-static strain measurement result based on the first reflected pulse electrical signal and the first electrical signal, and generate a vibration measurement result based on the second electrical signal.

9. The distributed multi-parameter sensing system according to claim 8, characterized in that: The distributed multi-parameter sensing system further includes a signal energy determination module, wherein the signal energy determination module is disposed between the heterogeneous parallel-band grating array and the signal processing module; The signal energy determination module is configured to determine a first signal energy value of the first reflected pulsed optical signal and a second signal energy value of the second reflected pulsed optical signal, and determine a first narrowband optical signal and a first broadband optical signal in the first reflected pulsed optical signal based on the first signal energy value and an energy threshold, and determine a second narrowband optical signal and a second broadband optical signal in the second reflected pulsed optical signal based on the second signal energy value and the energy threshold; The first photodetector is used to receive the first narrowband optical signal, the second photodetector is used to receive the second narrowband optical signal, and the balanced photodetector is used to receive the second broadband optical signal.

10. The distributed multi-parameter sensing system according to claim 8, characterized in that: The data acquisition card is further configured to receive the multiple trigger signals and generate temperature measurement results, vibration measurement results, and quasi-static strain measurement results based on the multiple trigger signals.

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