DFB-FL sensor state monitoring method and system

Abstract

The present application relates to the field of optical fiber sensor monitoring technology, and specifically to a DFB-FL sensor state monitoring method and system. The DFB-FL sensor state monitoring system includes: a DFB-FL sensor system, a first coupler, a first detection optical path, and a second detection optical path; the first coupler divides the optical signal output by the optical isolator in the DFB-FL sensor system into a first optical signal and a second optical signal; the first detection optical path divides the first optical signal into a third optical signal and a fourth optical signal, and detects a first voltage signal corresponding to the third optical signal; the second detection optical path generates an FBG optical signal corresponding to the fourth optical signal, and detects a second voltage signal corresponding to the FBG optical signal; the DFB-FL sensor state monitoring method includes: obtaining a first voltage signal and a second voltage signal; and determining the state of the DFB-FL sensor based on the first voltage signal and the second voltage signal.

Description

Technical Field

[0001] The present application relates to the field of optical fiber sensor monitoring technology, and in particular to a DFB-FL sensor state monitoring method and system. Background Art

[0002] Fiber optic sensors use optical fibers as sensitive or transmission elements, and have the advantages of being non-electrical, strong in anti-electromagnetic interference, high sensitivity, high temperature resistance, and corrosion resistance. DFB-FL is a single longitudinal mode laser based on rare earth doped optical fiber (such as erbium, thulium, ytterbium, etc.) integrated with a phase shift grating. Its core structure is to use ultraviolet light to write a Bragg grating with a π phase shift in the germanium-doped photosensitive optical fiber area, and use rare earth ions as the gain medium. Under the action of pump light, DFB-FL generates laser light that matches the Bragg wavelength of the phase shift grating, with the characteristics of narrow linewidth, low phase noise, and easy multiplexing, which is very suitable for dynamic monitoring.

[0003] Acoustic wave, vibration, strain and other sensors based on DFB-FL have the characteristics of high sensitivity, high signal-to-noise ratio and strong anti-interference ability, and have been widely used in hydrophone and acoustic sensing, power equipment monitoring, structural health monitoring, seismic detection, natural disaster monitoring and oil and gas exploration. When DFB-FL is used as a sensor, it is necessary to apply axial pre-tension through the sensitivity enhancement packaging structure (depending on the packaging design and sensitivity requirements) to improve its response to small strains.

[0004] However, there are two problems in the related technology: First, due to creep, temperature cycling or vibration of the packaging material, the pre-tension gradually decreases or even disappears, resulting in a decrease in sensor sensitivity or failure. Second, in order to reduce costs, ordinary single-mode optical fibers are usually fused at both ends of the DFB-FL, and the tensile strength of the fusion point is significantly lower than that of the original optical fiber. Under the combined effect of pre-tension and environmental stress, the fusion point is prone to breakage, resulting in loss of sensor function. For the aforementioned problems, there was no abnormality in the demodulation of the sensor's back-end instrument, but the sensor had failed.

[0005] Therefore, it is urgent to propose a new method for real-time monitoring of the operating status of the DFB-FL sensor to solve the above technical problems. Summary of the invention

[0006] To solve the above problems, the embodiments of the present application provide a DFB-FL sensor status monitoring method and system, which can monitor the fracture of welding points and the reduction of pre-tension in the DFB-FL sensor, and reduce the losses caused by the failed sensors in long-term operation.

[0007] In some embodiments, a DFB-FL sensor state monitoring method is provided, which is applied to a DFB-FL sensor state monitoring system, and the DFB-FL sensor state monitoring system includes: a DFB-FL sensor system, including an optical isolator; a first coupler, optically connected to the optical isolator, configured to divide an optical signal output by the optical isolator into a first optical signal and a second optical signal; a first detection optical path, optically connected to an optical outlet of the first coupler, configured to divide the first optical signal into a third optical signal and a fourth optical signal, and detect a first voltage signal corresponding to the third optical signal; a second detection optical path, optically connected to an optical outlet of the first detection optical path, configured to generate an FBG optical signal corresponding to the fourth optical signal, and detect a second voltage signal corresponding to the FBG optical signal; the DFB-FL sensor state monitoring method includes: acquiring a first voltage signal and a second voltage signal; and determining a state of the DFB-FL sensor based on the first voltage signal and the second voltage signal.

[0008] By adopting the DFB-FL sensor state monitoring method provided in the embodiment of the present application, the state of the DFB-FL sensor is determined through the first voltage signal and the second voltage signal to determine whether the DFB-FL sensor has problems such as the first welding point breaking, the second welding point breaking and the pre-tension reduction, thereby facilitating the early warning of the DFB-FL sensor.

[0009] Optionally, the DFB-FL sensor includes a DFB-FL, a first welding point and a second welding point, the first welding point and the second welding point are respectively located at two ends of the DFB-FL, the first welding point is close to the optical isolator, and the second welding point is far away from the optical isolator; the DFB-FL has a pre-tension; based on the first voltage signal and the second voltage signal, the state of the DFB-FL sensor is determined, including: when the first voltage signal is a first preset value, the state of the DFB-FL sensor is determined to be a first state; the first state indicates that the first welding point of the DFB-FL sensor is broken; when the second voltage signal is a second preset value, the state of the DFB-FL sensor is determined to be a second state; the second state indicates that the second welding point of the DFB-FL sensor is broken or the pre-tension is reduced.

[0010] Optionally, the first preset value is 0; the range of the second preset value is [-α, α], where α is a preset parameter.

[0011] In some embodiments, a DFB-FL sensor state monitoring system is provided, including: a DFB-FL sensor system, including an optical isolator; a first coupler, optically connected to the optical isolator, configured to divide an optical signal output by the optical isolator into a first optical signal and a second optical signal; a first detection optical path, optically connected to an optical outlet of the first coupler, configured to divide the first optical signal into a third optical signal and a fourth optical signal, and detect a first voltage signal corresponding to the third optical signal; a second detection optical path, optically connected to an optical outlet of the first detection optical path, configured to generate an FBG optical signal corresponding to the fourth optical signal, and detect a second voltage signal corresponding to the FBG optical signal; a detection module, communicatively connected to the first detection optical path and the second detection optical path; the detection module is configured to obtain a first voltage signal and a second voltage signal; and the state of the DFB-FL sensor is determined based on the first voltage signal and the second voltage signal.

[0012] It can be understood that the beneficial effects that can be achieved by the technical solution provided by the above-mentioned DFB-FL sensor state monitoring system can refer to the beneficial effects in the DFB-FL sensor state monitoring method and any of its optional implementations, and will not be repeated here.

[0013] Optionally, the first detection optical path includes: a second coupler, optically connected to the light outlet of the first coupler, configured to divide the first optical signal into a third optical signal and a fourth optical signal; a first photodetector, optically connected to the second coupler, configured to detect a first analog signal corresponding to the third optical signal; and a first analog-to-digital converter, communicatively connected to the first photodetector, configured to convert the first analog signal into a first voltage signal.

[0014] Optionally, the first coupler includes a first input end and a first output end, and the first coupler has a first splitting ratio; the first input end is optically connected to the optical isolator; the second coupler includes a second input end, a second output end and a third output end, and the second coupler has a second splitting ratio; the second input end is optically connected to the first output end; the third optical signal outputs the second coupler through the second output end, and the fourth optical signal outputs the second coupler through the third output end; the third output end is optically connected to the second detection optical path; the second output end is optically connected to the first photodetector to detect the first analog signal corresponding to the third optical signal.

[0015] Optionally, the second detection optical path includes: an FBG wide-bandwidth optical fiber, optically connected to the light outlet of the first detection optical path, and configured to generate an FBG optical signal corresponding to the fourth optical signal; a second photodetector, optically connected to the light outlet of the FBG wide-bandwidth optical fiber, and configured to detect a second analog signal corresponding to the FBG optical signal; and a second analog-to-digital converter, communicatively connected to the second photodetector, and configured to convert the second analog signal into a second voltage signal.

[0016] Optionally, the second detection optical path also includes: a ring fiber optic device, including a first interface, a second interface and a third interface; the first interface is optically connected to the light outlet of the first detection optical path; the FBG wide-bandwidth optical fiber is optically connected to the second interface; the second photodetector is optically connected to the third interface, and is configured to detect the optical signal output by the third interface.

[0017] Optionally, the DFB-FL sensor state monitoring system also includes: a DFB-FL sensor, including a distributed feedback fiber laser and a sensitivity enhancement packaging structure; both ends of an active fiber segment having a DFB grating in the distributed feedback fiber laser are fixed on the sensitivity enhancement packaging structure, and a pre-tension is applied to the active fiber segment along the axis; the sensitivity enhancement packaging structure is configured to increase the sensitivity of the DFB grating to physical variables.

[0018] Optionally, the DFB-FL sensor uses a single-mode optical fiber as an optical transmission medium; the two ends of the active optical fiber segment are respectively fused with the single-mode optical fiber to form a first fusion point and a second fusion point; the detection module is configured to determine the state of the DFB-FL sensor based on the first voltage signal and the second voltage signal, including: when the first voltage signal is a first preset value, determining that the state of the DFB-FL sensor is a first state; the first state indicates that the first fusion point of the DFB-FL sensor is broken; when the second voltage signal is a second preset value, determining that the state of the DFB-FL sensor is a second state; the second state indicates that the second fusion point of the DFB-FL sensor is broken or the pre-tension is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] Figure 1 A structural block diagram of a DFB-FL sensor state monitoring system provided in an embodiment of the present application;

[0021] Figure 2 A schematic diagram of the first structure of the DFB-FL sensor state monitoring system provided in an embodiment of the present application;

[0022] Figure 3 A schematic diagram of the structure of the DFB-FL sensor provided in an embodiment of the present application;

[0023] Figure 4 A schematic diagram of a first detection optical path provided in an embodiment of the present application;

[0024] Figure 5 A second structural schematic diagram of the DFB-FL sensor state monitoring system provided in an embodiment of the present application;

[0025] Figure 6 A schematic diagram of a second detection optical path provided in an embodiment of the present application;

[0026] Figure 7 A first flow chart of a DFB-FL sensor state monitoring method provided in an embodiment of the present application;

[0027] Figure 8 This is a second flow chart of the DFB-FL sensor state monitoring method provided in an embodiment of the present application.

[0028] Reference numerals:

[0029] 1. DFB-FL sensor status monitoring system;

[0030] 11. DFB-FL sensor system; 111. optical isolator; 112. pump light source; 113. wavelength division multiplexing module; 114. transmission optical fiber; 115. DFB-FL sensor; 1151. DFB grating; 1152. sensitivity enhancement packaging structure; 1153. single-mode optical fiber; 1154. first fusion point; 1155. second fusion point;

[0031] 12, first coupler; 121, first input end; 122, first output end; 123, fourth output end;

[0032] 13, first detection optical path; 131, second coupler; 1311, second input end; 1312, second output end; 1313, third output end; 132, first photodetector; 133, first analog-to-digital converter;

[0033] 14, second detection optical path; 141, FBG wide bandwidth optical fiber; 142, second photodetector; 143, second analog-to-digital converter; 144, ring optical fiber device; 1441, first interface; 1442, second interface; 1443, third interface;

[0034] 15. Detection module;

[0035] 16. Demodulation module; 161. Optical path component; 162. Third photodetector; 163. Third analog-to-digital converter. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be described clearly below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments of the present application, other embodiments obtained by ordinary technicians in this field without making creative work all belong to the protection scope of the present application.

[0037] In the following, the terms "first", "second", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0038] In addition, in the present application, directional terms such as "upper", "lower", "inner" and "outer" are defined relative to the orientation of the components schematically placed in the drawings. It should be understood that these directional terms are relative concepts. They are used for relative description and clarification, and they can change accordingly according to the changes in the orientation of the components placed in the drawings.

[0039] Fiber optic sensors use optical fibers as sensitive or transmission elements, and have the advantages of being non-electrical, strong in anti-electromagnetic interference, high sensitivity, high temperature resistance, and corrosion resistance. Distributed Feedback Fiber Laser (DFB-FL) is a single longitudinal mode laser based on rare earth doped optical fiber (such as erbium, thulium, ytterbium, etc.) integrated with a phase shift grating. Its core structure is to use ultraviolet light to write a Bragg grating with a π phase shift in the germanium-doped photosensitive optical fiber region, and use rare earth ions as the gain medium. Under the action of pump light, DFB-FL generates laser light that matches the Bragg wavelength of the phase shift grating, and has the characteristics of narrow linewidth, low phase noise, and easy multiplexing, which is very suitable for dynamic monitoring.

[0040] Acoustic wave, vibration, strain and other sensors based on DFB-FL have the characteristics of high sensitivity, high signal-to-noise ratio and strong anti-interference ability, and have been widely used in hydrophone and acoustic sensing, power equipment monitoring, structural health monitoring, seismic detection, natural disaster monitoring and oil and gas exploration. When DFB-FL is used as a sensor, it is necessary to apply axial pre-tension through the sensitivity enhancement packaging structure (depending on the packaging design and sensitivity requirements) to improve its response to small strains.

[0041] However, there are two problems in the related technology: First, due to creep of packaging materials, temperature cycles or vibration, the pre-tension gradually decreases or even disappears, resulting in decreased sensitivity or failure of the sensor. Second, in order to reduce costs, the two ends of the DFB-FL are usually fused with ordinary single-mode optical fibers, and the tensile strength of the fusion point is significantly lower than that of the original optical fiber. Under the combined effect of pre-tension and environmental stress, the fusion point is prone to breakage, resulting in loss of sensor function.

[0042] For the above two problems, there is no abnormality in the demodulation of the sensor's back-end instrument, but the sensor has failed.

[0043] In order to solve the above technical problems, the embodiments of the present application provide a DFB-FL sensor status monitoring method and system, which can realize the early warning of pre-tension reduction, the detection of the first weld point fracture and the second weld point fracture, thereby ensuring the effectiveness of the long-term operation of the DFB-FL sensor and avoiding the losses caused by abnormal operation of the sensor.

[0044] Figure 1 This is a structural block diagram of the DFB-FL sensor state monitoring system provided in an embodiment of the present application. Figure 2 A first structural schematic diagram of a DFB-FL sensor state monitoring system provided in an embodiment of the present application.

[0045] Combination Figure 1 As shown, the DFB-FL sensor state monitoring system 1 includes: a DFB-FL sensor system 11, a first coupler 12, a first detection optical path 13, a second detection optical path 14 and a detection module 15. Figure 2 As shown, the DFB-FL sensor system 11 includes an optical isolator 111. The first coupler 12 is optically connected to the optical isolator 111 and is configured to divide the optical signal output by the optical isolator 111 into a first optical signal and a second optical signal. The first detection optical path 13 is optically connected to the optical outlet of the first coupler 12 and is configured to divide the first optical signal into a third optical signal and a fourth optical signal, and detect a first voltage signal corresponding to the third optical signal. The second detection optical path 14 is optically connected to the optical outlet of the first detection optical path 13 and is configured to generate a FBG (Fiber Bragg Grating) optical signal corresponding to the fourth optical signal and detect a second voltage signal corresponding to the FBG optical signal. The detection module 15 is communicatively connected to the first detection optical path 13 and the second detection optical path 14. The detection module 15 is configured to obtain a first voltage signal and a second voltage signal; based on the first voltage signal and the second voltage signal, determine the state of the DFB-FL sensor 115.

[0046] The DFB-FL sensor state monitoring system 1 provided in the embodiment of the present application is used to separate part of the light output by the DFB-FL sensor 115 (i.e., the light output by the optical isolator) to determine the state of the DFB-FL sensor 115. Specifically, by detecting the first voltage signal corresponding to the separated light, it is possible to determine whether the DFB-FL sensor 115 has a problem of a front-end weld point break based on the presence or absence of the first voltage signal. By detecting the second voltage signal corresponding to the FBG optical signal corresponding to the separated light, it is possible to determine whether the DFB-FL sensor 115 has a problem of a rear-end weld point break or a reduction in pre-tension based on the magnitude of the second voltage signal.

[0047] Specifically, the optical isolator is configured to prevent the back-reflected light from entering the DFB-FL sensor system 11 to reduce the problems of laser instability and damage to the pump light source 112 .

[0048] Optionally, combined Figure 1 As shown, the DFB-FL sensor state monitoring system 11 further includes a demodulation module 16 . The demodulation module 16 is optically connected to the first coupler 12 and is configured to demodulate the second optical signal to obtain a physical quantity detected by the DFB-FL sensor system 11 .

[0049] Optionally, combined Figure 2 As shown, the DFB-FL sensor system 11 further includes: a pump light source 112, a wavelength division multiplexing module 113, a transmission optical fiber 114 and a DFB-FL sensor 115. The pump light source 112 is configured to provide gain for the laser output by the DFB-FL sensor 115. The wavelength division multiplexing module 113 is configured to separate / couple the pump light from the signal light. The transmission optical fiber 114 is configured to conduct the pump light and the laser signal. The DFB-FL sensor 115 is configured to generate a narrow line width laser through a built-in grating structure (such as a phase-shifted fiber grating), and convert external physical quantities (strain, temperature, vibration) into laser wavelength shift.

[0050] Specifically, the pump light source 112 is configured to provide light energy to excite rare earth ions in a doped optical fiber (such as an erbium-doped optical fiber) to cause them to transition to a high energy state, thereby forming a population inversion and providing gain for laser generation. Exemplarily, the pump light source 112 is a 980nm pump light source or a 1480nm pump light source.

[0051] The wavelength division multiplexing module 113 is a 980nm / 1550nm wavelength division multiplexing module or a 1480nm / 1550nm wavelength division multiplexing module.

[0052] Specifically, the pump light source 112 emits a 980nm or 1480nm wavelength pump light, which enters the wavelength division multiplexing module 113 through the 980nm or 1480nm end of the wavelength division multiplexing module 113, and then is output from the COM end of the wavelength division multiplexing module 113, passes through the transmission optical fiber 114, and enters the DFB-FL sensor 115 (because the DFB-FL sensor 115 is provided with a pre-tension of 0.2N-1N, the DFB-FL wavelength increases by about 0.2-1nm compared with the original wavelength). The DFB-FL sensor 115 emits laser light to propagate back along the optical fiber. When the DFB-FL sensor 115 senses external sound waves, vibrations, dynamic strains and other information, the wavelength of the laser emitted by the DFB-FL sensor 115 changes. The return light emitted by the DFB-FL sensor 115 enters the WDM, then is output through the 1550nm end and enters the optical isolator 111. The isolation direction of the optical isolator 111 is in the opposite direction of the return light emitted by the DFB-FL sensor 115 to prevent the scattered light in the rear optical path from affecting the light output of the DFB-FL sensor 115.

[0053] Figure 3 This is a schematic diagram of the structure of the DFB-FL sensor provided in an embodiment of the present application.

[0054] Optionally, combined Figure 3 As shown, the DFB-FL sensor 115 includes a distributed feedback fiber laser and a sensitivity enhancement packaging structure 1152; both ends of the active fiber segment having a DFB grating 1151 in the distributed feedback fiber laser are fixed on the sensitivity enhancement packaging structure 1152, and a pre-tension is applied to the active fiber segment along the axis; the sensitivity enhancement packaging structure 1152 is configured to increase the sensitivity of the DFB grating 1151 to physical variables.

[0055] In this embodiment, the sensitivity enhancement packaging structure 1152 is provided to improve the sensitivity of the DFB-FL to the physical quantity to be measured, thereby improving the accuracy of the demodulated physical quantity.

[0056] Optionally, combined Figure 3 As shown, the value range of the pre-tension force F is 0.2N to 1N. Exemplarily, the specific value of the pre-tension force is 0.2N, 0.6N or 1N.

[0057] Optionally, continue to refer to Figure 3, the DFB-FL sensor 115 uses a single-mode optical fiber 1153 as an optical transmission medium; the two ends of the active optical fiber segment are respectively fused with the single-mode optical fiber 1153 to form a first fusion point 1154 and a second fusion point 1155; the detection module 15 is configured to determine the state of the DFB-FL sensor 115 based on the first voltage signal and the second voltage signal, including: when the first voltage signal is a first preset value, determining that the state of the DFB-FL sensor 115 is a first state; the first state indicates that the first fusion point 1154 of the DFB-FL sensor 115 is broken; when the second voltage signal is a second preset value, determining that the state of the DFB-FL sensor 115 is a second state; the second state indicates that the second fusion point 1155 of the DFB-FL sensor 115 is broken or the pre-tension is reduced.

[0058] In this embodiment, the abnormality detection of the sensor state is implemented by the first voltage signal and the second voltage signal, thereby reducing the loss caused by the abnormal operation of the sensor.

[0059] Figure 4 A schematic diagram of a first detection optical path provided in an embodiment of the present application.

[0060] Optionally, combined Figure 4 As shown, the first detection optical path 13 includes: a second coupler 131, a first photodetector 132 and a first analog-to-digital converter 133. The second coupler 131 is optically connected to the light outlet of the first coupler 12, and the second coupler 131 is configured to divide the first optical signal into a third optical signal and a fourth optical signal. The first photodetector 132 is optically connected to the second coupler 131, and the first photodetector 132 is configured to detect a first analog signal corresponding to the third optical signal. The first analog-to-digital converter 133 is communicatively connected to the first photodetector 132, and the first analog-to-digital converter 133 is configured to convert the first analog signal into a first voltage signal.

[0061] In this embodiment, the second coupler 131, the first photodetector 132 and the first analog-to-digital converter 133 are used to detect the first voltage signal corresponding to the third optical signal, so as to determine whether the DFB-FL has a front-end welding point breakage problem.

[0062] Optionally, continue to refer to Figure 4The first coupler 12 includes a first input terminal 121 and a first output terminal 122, and the first coupler 12 has a first splitting ratio; the first input terminal 121 is optically connected to the optical isolator 111; the second coupler 131 includes a second input terminal 1311, a second output terminal 1312 and a third output terminal 1313, and the second coupler 131 has a second splitting ratio; the second input terminal 1311 is optically connected to the first output terminal 122; the third optical signal is output from the second coupler 131 through the second output terminal 1312, and the fourth optical signal is output from the second coupler 131 through the third output terminal 1313; the third output terminal 1313 is optically connected to the second detection optical path 14; the second output terminal 1312 is optically connected to the first photodetector 132 to detect the first analog signal corresponding to the third optical signal.

[0063] In this embodiment, the first optical signal is divided into a third optical signal and a fourth optical signal, and the third optical signal outputted from the second output terminal 1312 is detected by the first photodetector 132 connected to the second output terminal 1312, so as to detect whether the weld point of the DFB-FL sensor 115 is broken. In addition, the fourth optical signal is outputted to the second detection optical path 14 through the third output terminal 1313, so as to generate an FBG optical signal corresponding to the fourth optical signal, and detect the second voltage signal corresponding to the FBG optical signal, so as to further detect whether the weld point of the DFB-FL sensor 115 is broken and whether there is a problem of reduced pre-tension.

[0064] Specifically, the first splitting ratio is M 1 =B / A≥1, that is, B≥A. Figure 4 As shown, the first optical signal is B% of the optical signal output by the optical isolator 111, and the second optical signal is A% of the optical signal output by the optical isolator 111, that is, the intensity of the first optical signal is greater than or equal to the intensity of the second optical signal to ensure the validity of the acquired first voltage signal and the second voltage signal. For example, A%=20% and B%=80%.

[0065] The second splitting ratio is M 2 =D / C≥1, that is, D≥C. Figure 4 As shown, the third optical signal is C% of the first optical signal, and the fourth optical signal is D% of the first optical signal, that is, the intensity of the third optical signal is less than or equal to the intensity of the fourth optical signal. For example, set C%=30% and D%=70%.

[0066] Specifically, combined Figure 4 As shown, the first coupler 12 further includes a fourth output terminal 123, which is optically connected to the demodulation module 16. The second optical signal outputs the first coupler 12 through the fourth output terminal 123 to enter the demodulation module 16 to be demodulated to obtain a physical quantity corresponding to the fourth optical signal.

[0067] Figure 5 A second structural schematic diagram of the DFB-FL sensor state monitoring system provided in an embodiment of the present application.

[0068] Combination Figure 5 As shown, the demodulation module 16 includes: an optical path component 161, a third photodetector 162 and a third analog-to-digital converter 163. After the second optical signal enters the demodulation module 16, it first enters the optical path component 161 to generate a return light signal corresponding to the second optical signal, and the return light signal enters the third photodetector 162 to convert the return light signal into a third analog signal. The third analog signal enters the third analog-to-digital converter 163 for data acquisition to obtain a third voltage signal, and then the signal is demodulated by a demodulation algorithm based on FPGA to restore the measured physical information.

[0069] The optical path component 161 includes a Michelson interferometer optical component or a 3×3 coupler optical component. When the FPGA-based demodulation algorithm is a PGC (phase carrier demodulation) demodulation algorithm, the optical path component 161 is a Michelson interferometer optical component, and when the FPGA-based demodulation algorithm is an NPS (symmetric demodulation) demodulation algorithm, the optical path component 161 is a 3×3 coupler optical component.

[0070] It should be understood that in the embodiment of the present application, an analog-to-digital converter can be provided to realize analog-to-digital conversion of the first voltage signal, the second voltage signal, and the third voltage signal (eg, Figure 2 As shown in FIG. 1 ), three analog-to-digital converters (a first analog-to-digital converter 133, a second analog-to-digital converter 143, and a third analog-to-digital converter 163) may also be provided to respectively implement analog-to-digital conversion of the first voltage signal, the second voltage signal, and the third voltage signal (as shown in FIG. Figure 5 As shown), the present application does not limit the number of analog-to-digital converters, as long as they can realize analog-to-digital conversion of the first voltage signal, the second voltage signal, and the third voltage signal.

[0071] Specifically, if we use Figure 2 As shown, the first analog-to-digital converter 133, the second analog-to-digital converter 143 and the third analog-to-digital converter 163 are multiplexed into the same analog-to-digital converter to improve system integration and reduce system footprint.

[0072] Figure 6 A schematic diagram of a second detection optical path provided in an embodiment of the present application.

[0073] Optionally, combined Figure 6As shown, the second detection optical path 14 includes: a FBG wide bandwidth optical fiber 141, a second photodetector 142, and a second analog-to-digital converter 143. The FBG wide bandwidth optical fiber 141 is optically connected to the light outlet of the first detection optical path 13, and the FBG wide bandwidth optical fiber 141 is configured to generate a FBG optical signal corresponding to the fourth optical signal. The second photodetector 142 is optically connected to the light outlet of the FBG wide bandwidth optical fiber 141, and the second photodetector 142 is configured to detect a second analog signal corresponding to the FBG optical signal. The second analog-to-digital converter 143 is communicatively connected to the second photodetector 142, and the second analog-to-digital converter 143 is configured to convert the second analog signal into a second voltage signal.

[0074] In this embodiment, after the fourth optical signal enters the FBG wide bandwidth optical fiber 141, FBG return light (ie, FBG optical signal) is generated, and the intensity of the FBG return light is detected to determine whether the DFB-FL sensor 115 has a fusion point break and a pre-tension reduction problem.

[0075] Optionally, combined Figure 6 As shown, the second detection optical path 14 also includes: a ring optical fiber 144. The ring optical fiber 144 includes a first interface 1441, a second interface 1442 and a third interface 1443; the first interface 1441 is optically connected to the light outlet of the first detection optical path 13. The FBG wide bandwidth optical fiber 141 is optically connected to the second interface 1442. The second photodetector 142 is optically connected to the third interface 1443, and is configured to detect the optical signal output by the third interface 1443 to generate a second analog signal.

[0076] In this embodiment, by setting up the annular fiber optic device 144, the FBG wide-bandwidth fiber 141, and the second photodetector 142, the fourth optical signal is converted into the corresponding FBG optical signal, and the second analog signal corresponding to the FBG optical signal is detected, thereby facilitating the monitoring of the state of the DFB-FL sensor 115 based on the second voltage signal, so as to determine whether the DFB-FL sensor 115 has problems of melting point breakage and reduced pre-tension.

[0077] Table 1 is a table showing the relationship between the abnormal state of the DFB-FL sensor 115 and the first voltage signal and the second voltage signal. In combination with the following Table 1 and the first voltage signal and the second voltage signal obtained in the DFB-FL sensor state monitoring system 1 provided in the embodiment of the present application, the abnormal detection of the DFB-FL sensor 115 in the present application is described.

[0078] Table 1

[0079] ;

[0080] The value range of α is [0, 0.5].

[0081] When the first welding point 1154 is not broken and the DFB-FL sensor 115 operates normally, the first voltage signal is not 0. When the first welding point 1154 is broken, the first voltage signal is 0.

[0082] According to the optical and physical properties of DFB-FL, when the axial tension on DFB-FL is FN, the wavelength of DFB-FL changes by Δλ 拉 ≈Fnm. If the bandwidth of the FBG wide bandwidth optical fiber 141 is bnm, the pre-tension F is set to F>b / 2N. When the pre-tension F>b / 2N, the wavelength of the DFB-FL is sufficiently different from the central wavelength of the FBG wide bandwidth optical fiber 141, exceeding the reflection bandwidth of the FBG wide bandwidth optical fiber 141, resulting in the second photodetector 142 not being able to detect the reflected light, so the output voltage second voltage signal is in the interval [-α, α], that is, approximately equal to 0. In the case of the second fusion point 1155 being broken, the pre-tension F=0N, resulting in the wavelength change of the DFB-FL Δλ 拉 ≈0nm, that is, the DFB-FL wavelength coincides with the FBG center wavelength, the FBG wide-bandwidth optical fiber 141 will reflect the wavelength optical signal matching its bandwidth, and the second voltage signal is not within the interval [-α, α].

[0083] Therefore, when the second welding point 1155 is not broken and the DFB-FL sensor 115 operates normally, the second voltage signal is within the interval [-α, α]. When the second welding point 1155 is broken, the second voltage signal is not within the interval [-α, α].

[0084] Combined with the above description, it can be seen that when the pre-tension is reduced so that the wavelength of DFB-FL coincides with the central wavelength of FBG, the second voltage signal may not be within the interval [-α, α]. When the axial pre-tension of DFB-FL is FN, the wavelength of DFB-FL changes Δλ 拉 ≈Fnm, if it is set that an early warning is generated when the axial pre-tension of the DFB-FL becomes F / 2N, then the bandwidth of the FBG wide-bandwidth optical fiber 141 is required to be greater than or equal to 2Fnm.

[0085] When the axial pretension of the DFB-FL is greater than F / 2N, the second voltage signal is within the interval [-α, α]. When the axial pretension of the DFB-FL is less than or equal to F / 2N, the second voltage signal is not within the interval [-α, α].

[0086] Optionally, the preset pre-tension of the DFB-FL is F / 2N, requiring the bandwidth of the FBG wide-bandwidth optical fiber 141 to be ≥2Fnm. It can be understood that when the second fusion point 1155 is broken, it can also be understood as a situation where the pre-tension is reduced. At this time, it is only necessary to determine that the DFB-FL sensor 115 may have a problem of the second fusion point 1155 being broken or the pre-tension being reduced when the second voltage signal is within the interval [-α, α], and determine that the DFB-FL sensor 115 needs to be repaired or replaced at this time, so as to reduce the loss caused by the long-term abnormal operation of the DFB-FL sensor 115.

[0087] Figure 7 This is the first flow chart of the DFB-FL sensor state monitoring method provided in an embodiment of the present application.

[0088] Combination Figure 2 or Figure 5 The DFB-FL sensor state monitoring system 1 shown in the figure, the embodiment of the present application also provides a DFB-FL sensor state monitoring method, the execution subject of the method can be the detection module 15. Figure 7 As shown, the monitoring method includes step S1 and step S2, which are specifically as follows:

[0089] Step S1, acquiring a first voltage signal and a second voltage signal.

[0090] Step S2 , determining the state of the DFB-FL sensor 115 based on the first voltage signal and the second voltage signal.

[0091] Optionally, step S2 includes step S21 and step S22, which are specifically as follows:

[0092] Step S21 , when the first voltage signal is a first preset value, determining that the state of the DFB-FL sensor 115 is a first state; the first state indicates that the first welding point 1154 of the DFB-FL sensor 115 is broken.

[0093] Step S22 , when the second voltage signal is a second preset value, determining that the state of the DFB-FL sensor 115 is a second state; the second state indicates that the second welding point 1155 of the DFB-FL sensor 115 is broken or the pre-tension is reduced.

[0094] In this embodiment, it can be determined that the DFB-FL is in an abnormal state through the first voltage signal and the second voltage signal, and the DFB-FL sensor 115 should be repaired or replaced in time to reduce the loss caused by the abnormal operation of the sensor.

[0095] Optionally, the first preset value is 0. The range of the second preset value is [-α, α], where α is a preset parameter.

[0096] Optionally, the value range of α is [0, 0.5]. Exemplarily, the specific value of α is 0, 0.25 or 0.5.

[0097] By adopting the DFB-FL sensor 115 status monitoring method provided in the embodiment of the present application, the status of the DFB-FL sensor 115 is determined through the first voltage signal and the second voltage signal to determine whether the DFB-FL sensor 115 has problems such as the first welding point 1154 being broken, the second welding point 1155 being broken, and the pre-tension being reduced, thereby facilitating the early warning of the DFB-FL sensor 115.

[0098] Figure 8 This is a second flow chart of the DFB-FL sensor 115 state monitoring method provided in an embodiment of the present application.

[0099] Optionally, combined Figure 8 As shown, step S2 also includes step S3, which is as follows:

[0100] Step S3, when the state is an abnormal state, a warning signal corresponding to the state is issued. The abnormal state includes the first state and / or the second state.

[0101] In this way, active alarm of abnormal status can be achieved, reducing the losses caused by abnormal operation of the sensor.

[0102] It should be noted that those skilled in the art will easily think of other embodiments of the present application after considering the specification and practicing the application disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary technical means in the art that are not disclosed in the present application. The specification and examples are only regarded as exemplary, and the true scope of the present application is indicated by the claims.

[0103] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A DFB-FL sensor state monitoring method, characterized in that: Applicable to a DFB-FL sensor state monitoring system (1), the DFB-FL sensor state monitoring system (1) comprising: A DFB-FL sensor system (11), comprising an optical isolator (111) and a DFB-FL sensor (115); A first coupler (12), optically connected to the optical isolator (111), configured to split the optical signal output by the optical isolator (111) into a first optical signal and a second optical signal; A first detection optical path (13) is optically connected to the light outlet of the first coupler (12), and is configured to split the first optical signal into a third optical signal and a fourth optical signal, and detect a first voltage signal corresponding to the third optical signal; A second detection optical path (14) is optically connected to the light outlet of the first detection optical path (13), and is configured to generate an FBG optical signal corresponding to the fourth optical signal, and detect a second voltage signal corresponding to the FBG optical signal; The DFB-FL sensor state monitoring method comprises: Acquire the first voltage signal and the second voltage signal; determining a state of the DFB-FL sensor (115) based on the first voltage signal and the second voltage signal; The DFB-FL sensor (115) comprises a distributed feedback fiber laser, a first fusion point (1154) and a second fusion point (1155), wherein the first fusion point (1154) and the second fusion point (1155) are respectively located at two ends of the DFB-FL, the first fusion point (1154) is close to the optical isolator (111), and the second fusion point (1155) is far from the optical isolator (111); the distributed feedback fiber laser has a pre-tension; The determining the state of the DFB-FL sensor (115) based on the first voltage signal and the second voltage signal comprises: When the first voltage signal is a first preset value, determining that the state of the DFB-FL sensor (115) is a first state; the first state indicates that the first welding point (1154) of the DFB-FL sensor (115) is broken; When the second voltage signal is a second preset value, it is determined that the state of the DFB-FL sensor (115) is a second state; the second state indicates that the second welding point (1155) of the DFB-FL sensor (115) is broken or the pre-tension force is reduced.

2. The DFB-FL sensor state monitoring method according to claim 1, characterized in that: The first preset value is 0; The range of the second preset value is [-α, α], where α is a preset parameter.

3. A DFB-FL sensor state monitoring system, characterized in that: include: A DFB-FL sensor system (11), comprising an optical isolator (111) and a DFB-FL sensor (115); A first coupler (12), optically connected to the optical isolator (111), configured to split the optical signal output by the optical isolator (111) into a first optical signal and a second optical signal; A first detection optical path (13) is optically connected to the light outlet of the first coupler (12), and is configured to split the first optical signal into a third optical signal and a fourth optical signal, and detect a first voltage signal corresponding to the third optical signal; A second detection optical path (14) is optically connected to the light outlet of the first detection optical path (13), and is configured to generate an FBG optical signal corresponding to the fourth optical signal, and detect a second voltage signal corresponding to the FBG optical signal; a detection module (15) communicatively connected to the first detection optical path (13) and the second detection optical path (14); the detection module (15) is configured to obtain the first voltage signal and the second voltage signal; and determine the state of the DFB-FL sensor (115) based on the first voltage signal and the second voltage signal; The DFB-FL sensor (115) comprises a distributed feedback fiber laser and a sensitivity enhancement packaging structure (1152); Two ends of an active optical fiber segment having a DFB grating (1151) in the distributed feedback optical fiber laser are fixed on the sensitivity enhancement packaging structure (1152), and a pre-tension force is applied to the active optical fiber segment along the axis; The sensitivity enhancement packaging structure (1152) is configured to increase the sensitivity of the DFB grating (1151) to physical variables; The DFB-FL sensor (115) uses a single-mode optical fiber (1153) as an optical transmission medium; Two ends of the active optical fiber segment are respectively fused to the single-mode optical fiber (1153) to form a first fusion point (1154) and a second fusion point (1155); The detection module (15) is configured to determine the state of the DFB-FL sensor (115) based on the first voltage signal and the second voltage signal, comprising: When the first voltage signal is a first preset value, determining that the state of the DFB-FL sensor (115) is a first state; The first state indicates that the first welding point (1154) of the DFB-FL sensor (115) is broken; When the second voltage signal is a second preset value, it is determined that the state of the DFB-FL sensor (115) is a second state; the second state indicates that the second welding point (1155) of the DFB-FL sensor (115) is broken or the pre-tension force is reduced.

4. The DFB-FL sensor state monitoring system according to claim 3, characterized in that: The first detection optical path (13) comprises: A second coupler (131), optically connected to the light outlet of the first coupler (12), configured to split the first optical signal into a third optical signal and a fourth optical signal; A first photodetector (132), optically connected to the second coupler (131), configured to detect a first analog signal corresponding to the third optical signal; The first analog-to-digital converter (133) is communicatively connected to the first photodetector (132) and is configured to convert the first analog signal into the first voltage signal.

5. The DFB-FL sensor state monitoring system according to claim 4, characterized in that: The first coupler (12) comprises a first input end (121) and a first output end (122), and the first coupler (12) has a first splitting ratio; the first input end (121) is optically connected to the optical isolator (111); The second coupler (131) comprises a second input end (1311), a second output end (1312) and a third output end (1313); the second coupler (131) has a second splitting ratio; the second input end (1311) is optically connected to the first output end (122); the third optical signal is output from the second coupler (131) via the second output end (1312), and the fourth optical signal is output from the second coupler (131) via the third output end (1313); the third output end (1313) is optically connected to the second detection optical path (14); The second output end (1312) is optically connected to the first photodetector (132) to detect the first analog signal corresponding to the third optical signal.

6. The DFB-FL sensor state monitoring system according to claim 3, characterized in that: The second detection optical path (14) comprises: An FBG wide bandwidth optical fiber (141), optically connected to the light outlet of the first detection optical path (13), and configured to generate an FBG optical signal corresponding to the fourth optical signal; A second photodetector (142), optically connected to the light outlet of the FBG wide bandwidth optical fiber (141), configured to detect a second analog signal corresponding to the FBG optical signal; The second analog-to-digital converter (143) is communicatively connected to the second photodetector (142) and is configured to convert the second analog signal into the second voltage signal.

7. The DFB-FL sensor state monitoring system according to claim 6, characterized in that: The second detection optical path (14) further comprises: The ring optical fiber device (144) comprises a first interface (1441), a second interface (1442) and a third interface (1443); the first interface (1441) is optically connected to a light outlet of the first detection optical path (13); The FBG wide bandwidth optical fiber (141) is optically connected to the second interface (1442); The second photodetector (142) is optically connected to the third interface (1443) and is configured to detect an optical signal output by the third interface (1443).

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