Temperature sensor and temperature detection system based on identical fiber bragg grating

Abstract

The utility model discloses a temperature sensor and a temperature detection system based on identical fiber bragg gratings, and relates to the field of photon integration and fiber bragg grating sensing, and the device comprises a broadband light source, an identical weak reflection fiber bragg grating sensor array and a signal demodulation module. The signal demodulation module is integrated on a silicon substrate; the broadband light source and the signal demodulation module are connected with the identical weak reflection fiber grating sensor array; and the identical weak reflection fiber grating sensor array is placed at a temperature position to be measured. According to the temperature sensor and the temperature detection system based on the identical fiber bragg grating, the coupler and the chirped waveguide grating in the signal demodulation module are integrated on the silicon substrate, so that the device is more compact, an integrated chip is realized by adopting a photoelectron integration technology, and temperature demodulation and temperature detection are realized.

Description

Technical Field

[0001] The utility model relates to the field of photon integration and optical fiber grating sensing, in particular to a temperature sensor based on an identical optical fiber grating and a temperature detection system. Background Art

[0002] As an important sensing element, temperature sensors play a vital role in industrial production, environmental monitoring, and healthcare. With the continuous advancement of technology, fiber-optic temperature sensors have gradually become a new research and application hotspot due to their unique advantages, such as ease of manufacture, small size, low cost, durability, and excellent resistance to electromagnetic interference. Among them, segmented temperature sensing arrays based on chirped fiber Bragg grating demodulation, by leveraging the fiber Bragg grating's sensitivity to temperature changes and combining it with the filtering effect of the chirped fiber Bragg grating, achieve segmented real-time temperature measurement and early warning, greatly expanding the application range of fiber-optic temperature sensors.

[0003] However, while existing solutions have made some progress in segmented temperature measurement, they still have significant limitations. Specifically, these solutions face the problem of large space requirements in practical applications. Due to the large number of system components, the layout and connection of these components require a large amount of physical space, which is not conducive to application in compact or complex environments.

[0004] In addition, the connection process between optical fibers is complex and tedious, involving multiple steps. This not only increases the difficulty of system installation and maintenance, but may also cause damage to the optical fiber structure due to improper operation during the connection process, affecting the performance and life of the sensor. Utility Model Content

[0005] The purpose of the utility model is to provide a temperature sensor and temperature detection system based on an identical fiber Bragg grating, aiming to solve the technical problems of the existing fiber temperature sensing system in that the fiber connection is complex and fragile.

[0006] To achieve the above purpose, the present invention provides the following solutions:

[0007] In a first aspect, the present invention provides a temperature sensor based on an identical fiber Bragg grating, comprising:

[0008] Broadband light source, identical weak reflection fiber Bragg grating sensor array and signal demodulation module;

[0009] The signal demodulation module is integrated on a silicon base;

[0010] The broadband light source and the signal demodulation module are both connected to the identical weak reflection fiber Bragg grating sensor array;

[0011] The broadband light source is used to transmit optical signals to the identical weak-reflection fiber Bragg grating sensor array;

[0012] The identical weak-reflection fiber Bragg grating sensor array is used to receive the light signal emitted by the broadband light source and reflect it to obtain a reflected light signal, and transmit the reflected light signal to the signal demodulation module;

[0013] The signal demodulation module is used to demodulate the reflected light signal;

[0014] The identical weak reflection fiber grating sensor array is placed at the temperature position to be measured.

[0015] Optionally, the signal demodulation module specifically includes: a coupler component and a chirped waveguide grating;

[0016] The coupler assembly is connected to the chirped waveguide grating via a waveguide;

[0017] The coupler assembly is used to split the reflected light signal and transmit the split reflected light signal to the chirped waveguide grating;

[0018] The chirped waveguide grating is used to demodulate the received split reflected light signal.

[0019] Optionally, the coupler assembly specifically includes: a first coupler group, a second coupler group, and a third coupler group;

[0020] The input end of the first coupler group is connected to the isotropic weak-reflection fiber Bragg grating sensor array, the output end of the first coupler group is connected to the input end of the second coupler group, the output end of the second coupler group is connected to the input end of the third coupler group, and the output end of the third coupler group is connected to the input end of the chirped waveguide grating.

[0021] Optionally, the first coupler group, the second coupler group, and the third coupler group all include 1×2 couplers.

[0022] Optionally, the number of 1×2 couplers in the first coupler group, the second coupler group, and the third coupler group is 1, 2, and 4, respectively.

[0023] Optionally, the temperature sensor based on the identical fiber Bragg grating further comprises: a circulator;

[0024] The first port of the circulator is connected to a broadband light source through an optical fiber, the second port of the circulator is connected to an isotropic weak-reflection fiber Bragg grating sensor array, and the third port of the circulator is connected to an input end of a signal demodulation module through a waveguide.

[0025] In a second aspect, the present invention provides a temperature detection system, which includes a temperature sensor based on an identical fiber Bragg grating and a photoelectric detector;

[0026] The photoelectric detector is connected to the temperature sensor based on the identical fiber Bragg grating through an optical fiber, and is used for converting the optical signal demodulated by the temperature sensor based on the identical fiber Bragg grating into an electrical signal.

[0027] Optionally, the temperature detection system further comprises: a warning device;

[0028] The warning device is electrically connected to the photoelectric detector and is used to receive the electrical signal sent by the photoelectric detector and perform segmented real-time temperature measurement and early warning.

[0029] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0030] The present invention provides a temperature sensor and temperature detection system based on fully identical fiber Bragg gratings, which are suitable for industrialization and mass production. By integrating the signal demodulation module on a silicon substrate, the technical difficulties of the complex and fragile optical fiber connection between the coupler and the chirped fiber Bragg grating, which occupies a large space, are solved on the basis of reducing the production cost, and the overall volume of the system is greatly reduced, making the device more compact and portable. In addition, the multiple couplers and chirped waveguide gratings in the signal demodulation module are connected by waveguides, which simplifies the connection steps between optical fibers used in the prior art, reduces the risk of optical fiber loss and damage caused by multiple connections and disassembly, improves the reliability and durability of the temperature sensor and the temperature detection system, and also improves the accuracy and speed of signal processing through the stability of waveguide transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 This is a diagram of a segmented temperature measurement and real-time early warning device based on fiber Bragg grating in the prior art;

[0033] Figure 2 This is a schematic structural diagram of a temperature sensor based on an identical fiber Bragg grating in one embodiment of the present invention;

[0034] Figure 3 This is a structural diagram of a temperature detection system in one embodiment of the present invention.

[0035] Figure numerals: 101-signal demodulation module, 1-identical weak-reflection fiber Bragg grating sensor array, 2-broadband light source, 3-chirped waveguide grating, 4-photodetector, 5-circulator, 6-coupler assembly, 60-first coupler group, 61-second coupler group, 62-third coupler group, 7-warning device, 8-long-distance single-mode transmission optical fiber, 9-fiber Bragg grating sensor array, 10-1×N coupler, 11-filter, 12-warning light. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0038] First, some technical terms involved in the embodiments of the present utility model are introduced.

[0039] Fiber Bragg grating (FBG) utilizes the photosensitivity of optical fiber materials. Through ultraviolet exposure, it forms a permanent, periodic variation in refractive index along the fiber core's axis. Essentially, it forms a narrowband reflective (or transmissive) optical filter within the fiber core. FBG-based sensing acquires sensor information by modulating its central wavelength with external parameters (such as stress, vibration, and temperature). Therefore, FBG is a wavelength-modulated fiber sensor. FBG sensors can be used to detect a variety of parameters, including stress, strain, pressure, vibration, and temperature.

[0040] Identical weak-reflection fiber Bragg gratings (FBGs) are fabricated on optical fibers during the fiber drawing process using ultraviolet light. This allows the FBGs to be fabricated during the fiber drawing process. This method produces FBGs with essentially uniform reflection wavelengths and low reflectivity. FBGs fabricated in this manner can be mass-produced, potentially supporting thousands of FBG sensing points, meeting the needs of large-scale sensor deployments. Furthermore, due to industrial production, the product is inexpensive. The sensing principle of weak-reflection FBGs is similar to that of conventional FBGs. When the external temperature changes, the grating period of the FBG changes due to thermal expansion and contraction. Simultaneously, due to the thermo-optical effect, the refractive index of the FBG also changes with temperature. Overall, the reflected wavelength of the FBG changes proportionally with temperature. A chirped FBG is a type of grating fabricated on an optical fiber. Its grating period gradually changes from small to large, unlike the fixed period of conventional FBGs. Since the grating period of the chirped fiber Bragg grating changes gradually, its reflection spectrum has a certain reflection width.

[0041] For ease of understanding, a segmented temperature measurement and real-time warning device based on fiber Bragg grating is used as an example for illustration.

[0042] See also Figure 1The figure shows a real-time warning device for segmented temperature measurement based on fiber Bragg gratings. In this example, the optical signal emitted by the broadband light source 2 enters the first port of the circulator 5 through the optical fiber. The optical signal is output from the second port of the circulator 5 and input into the optical input port of the fiber Bragg grating sensor array 9 through the long-distance single-mode transmission optical fiber 8. The fiber Bragg grating sensor array 9 can reflect the optical signal of the corresponding wavelength back to the circulator 5 and transmit the reflected optical signal to the input port of the coupler 10 through the third port of the circulator 5. The 1×N coupler 10 can split the input reflected optical signal into N beams. Each beam of the reflected optical signal is connected to N filters 11 through its own pigtail. The reflected optical signal filtered by the filter 11 is incident on the input end of the photodetector 4. The photodetector 4 converts the filtered reflected optical signal into an electrical signal and drives the warning light 12. The warning light 12 will reflect the temperature warning information. When the temperature near a certain position or multiple positions in the fiber Bragg grating sensor array 9 increases, the reflected wavelength of the fiber Bragg grating at the corresponding position will change due to the temperature. When the temperature rises, the wavelength of the reflected light wave will move toward the long wavelength direction. When the temperature drops, the wavelength of the reflected light wave will move toward the short wavelength direction. The reflected light signal enters the 1×N coupler 10 through the third port of the circulator 5. The 1×N coupler 10 splits the reflected light into N beams. Each beam of reflected light signal after splitting is connected to N filters 11 through its own channel. The bandwidth of the N filters 11 is the same, and the central wavelength increases linearly. The 1-N filters 11 increase the wavelength band by an equal amount every Δλ. The device can provide segmented temperature warning. After the temperature rises, the filters 11 with the same bandwidth but different central wavelengths can effectively filter out the reflected light waves in a specific band. The filtered light waves are finally connected to the warning light 12 through the photoelectric detector 4, thereby realizing segmented real-time temperature measurement and warning.

[0043] Related technologies usually rely on the efficient transmission characteristics of single-mode transmission optical fiber and the temperature sensitivity of fiber Bragg grating to achieve long-distance, high-precision temperature monitoring.

[0044] However, the above solution does not consider the problem of large space occupation and complex optical fiber connection, and the movement and placement of 2, 4, 5, 10, 11, and 12 of the above solution are prone to damage the optical fiber structure. In view of this, the embodiment of the present invention provides a temperature sensor based on an identical fiber Bragg grating, such as Figure 2As shown, it includes: a broadband light source 2, an identical weak-reflection fiber Bragg grating sensor array 1 and a signal demodulation module 101. The signal demodulation module 101 is integrated on a silicon substrate; the broadband light source 2 and the signal demodulation module 101 are both connected to the identical weak-reflection fiber Bragg grating sensor array 1. The broadband light source 2 is used to transmit an optical signal to the identical weak-reflection fiber Bragg grating sensor array 1; the identical weak-reflection fiber Bragg grating sensor array 1 is used to receive the optical signal emitted by the broadband light source 2 and reflect it to obtain a reflected optical signal, and transmit the reflected optical signal to the signal demodulation module 101; the signal demodulation module 101 is used to demodulate the reflected optical signal; the identical weak-reflection fiber Bragg grating sensor array 1 is placed at the temperature to be measured.

[0045] As an optional embodiment, the signal demodulation module 101 specifically includes: a coupler component 6 and a chirped waveguide grating 3. The coupler component 6 is connected to the chirped waveguide grating 3 via a waveguide; the coupler component 6 is used to split the reflected light signal and transmit the splitted reflected light signal to the chirped waveguide grating 3; the chirped waveguide grating 3 is used to demodulate the received splitted reflected light signal.

[0046] In this embodiment, the coupler assembly 6 specifically includes: a first coupler group 60, a second coupler group 61 and a third coupler group 62; the input end of the first coupler group 60 is connected to the identical weak-reflection fiber Bragg grating sensor array 1, the output end of the first coupler group 60 is connected to the input end of the second coupler group 61, the output end of the second coupler group 61 is connected to the input end of the third coupler group 62, and the output end of the third coupler group 62 is connected to the input end of the chirped waveguide grating 3.

[0047] The first coupler group 60 , the second coupler group 61 , and the third coupler group 62 all include 1×2 couplers; the number of 1×2 couplers in the first coupler group 60 , the second coupler group 61 , and the third coupler group 62 are 1, 2, and 4, respectively.

[0048] As an optional embodiment, the temperature sensor based on identical fiber Bragg gratings also includes: a circulator 5; the first port of the circulator 5 is connected to the broadband light source 2 through an optical fiber, the second port of the circulator 5 is connected to the identical weak-reflection fiber Bragg grating sensor array 1, and the third port of the circulator 5 is connected to the input end of the signal demodulation module 101 through a waveguide.

[0049] In the second aspect, the utility model provides a temperature detection system, which includes a temperature sensor based on an identical fiber Bragg grating and a photodetector; the photodetector 4 is connected to the temperature sensor based on an identical fiber Bragg grating through an optical fiber, and is used to convert the optical signal demodulated by the temperature sensor based on the identical fiber Bragg grating into an electrical signal.

[0050] As an optional embodiment, the temperature detection system further includes: a warning device 7; the warning device 7 is electrically connected to the photoelectric detector 4, and is used to receive the electrical signal sent by the photoelectric detector 4 to perform segmented real-time temperature measurement and early warning.

[0051] In another exemplary embodiment of the present invention, Figure 3 As shown, the temperature detection system includes: an identical weak-reflection fiber Bragg grating sensor array 1, a broadband light source 2, a chirped waveguide grating 3, a photodetector 4, a circulator 5, a first coupler group 60, a second coupler group 61, a third coupler group 62 and a warning device 7.

[0052] The optical signal emitted from the broadband light source 2 on the silicon chip enters the input end of the identical weak-reflection fiber Bragg grating sensor array 1 through the waveguide. The identical weak-reflection fiber Bragg grating sensor array 1 can reflect the optical signal of the corresponding wavelength back to the circulator 5, and transmit the reflected optical signal to the input port of the first coupler group 60 through the circulator 5. The reflected optical signal can be proportionally split into two beams through a 1×2 coupler in the first coupler group 60. Each beam of the reflected optical signal after splitting is connected to the second coupler group 61 through its own waveguide. The input end is connected. The two 1×2 couplers in the second coupler group 61 divide the reflected light signal input from the first coupler group 6 into four beams in equal proportion. Each split reflected light signal is connected to the input end of the third coupler group 62 through its own waveguide. The eight output ends of the four 1×2 couplers in the third coupler group 62 are connected to the eight chirped waveguide gratings 3. The four 1×2 couplers in the third coupler group 62 divide the reflected light signal input from the second coupler group 61 into eight beams in equal proportion and input them into the eight chirped waveguide gratings 3. The eight chirped waveguide gratings 3 are connected to eight photodetectors 4. The chirped waveguide gratings 3 transmit the demodulated reflected light signals to the input ends of the photodetectors 4. The photodetectors 4 receive the reflected light signals related to temperature changes, convert them into electrical signals, and drive the warning device 7. The warning device 7 responds to temperature warning information, thereby achieving temperature change monitoring.

[0053] When the temperature increases near a certain location or multiple locations in the identical weak-reflection fiber Bragg grating sensor array 1, the chirped waveguide grating 3 at the corresponding location will change due to the temperature. When the temperature rises, the wavelength of the reflected light wave will shift toward longer wavelengths, and when the temperature drops, the wavelength of the reflected light wave will shift toward shorter wavelengths. This temperature detection system can monitor the temperature in segments. After the temperature rises, the chirped waveguide grating 3 with the same bandwidth but different center wavelengths can effectively filter out the reflected light waves in a specific wavelength band. The filtered light waves are converted into corresponding electrical signals by the photodetector 4 and transmitted to the warning device 7. This electrical signal represents the temperature change in the monitored area, thus achieving segmented real-time temperature measurement.

[0054] The key technologies of the device that can realize a temperature sensor based on identical fiber Bragg grating and temperature detection system are:

[0055] Using photonic integration, the chirped waveguide grating, the first coupler group, the second coupler group, and the third coupler group were inscribed using waveguide technology. A 9mm channel was first inscribed on a silicon wafer, followed by silicon dioxide deposition, and then the grating was inscribed using hydrogen-carrying technology. Indium gallium arsenide photodetectors were used as photodetectors.

[0056] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A temperature sensor based on an identical fiber Bragg grating, characterized in that: The temperature sensor based on identical fiber Bragg gratings comprises: a broadband light source, an identical weak reflection fiber Bragg grating sensor array and a signal demodulation module; The signal demodulation module is integrated on a silicon base; The broadband light source and the signal demodulation module are both connected to the identical weak reflection fiber Bragg grating sensor array; The broadband light source is used to transmit optical signals to the identical weak-reflection fiber Bragg grating sensor array; The identical weak-reflection fiber Bragg grating sensor array is used to receive the light signal emitted by the broadband light source and reflect it to obtain a reflected light signal, and transmit the reflected light signal to the signal demodulation module; The signal demodulation module is used to demodulate the reflected light signal; The identical weak reflection fiber grating sensor array is placed at the temperature position to be measured.

2. The temperature sensor based on identical fiber Bragg grating according to claim 1, characterized in that: The signal demodulation module specifically includes: a coupler component and a chirped waveguide grating; The coupler assembly is connected to the chirped waveguide grating via a waveguide; The coupler assembly is used to split the reflected light signal and transmit the split reflected light signal to the chirped waveguide grating; The chirped waveguide grating is used to demodulate the received split reflected light signal.

3. The temperature sensor based on identical fiber Bragg grating according to claim 2, characterized in that: The coupler assembly specifically includes: a first coupler group, a second coupler group, and a third coupler group; The input end of the first coupler group is connected to the isotropic weak-reflection fiber Bragg grating sensor array, the output end of the first coupler group is connected to the input end of the second coupler group, the output end of the second coupler group is connected to the input end of the third coupler group, and the output end of the third coupler group is connected to the input end of the chirped waveguide grating.

4. The temperature sensor based on identical fiber Bragg grating according to claim 3, characterized in that: The first coupler group, the second coupler group, and the third coupler group all include 1×2 couplers.

5. The temperature sensor based on identical fiber Bragg grating according to claim 4, characterized in that: The number of 1×2 couplers in the first coupler group, the second coupler group, and the third coupler group is 1, 2, and 4, respectively.

6. The temperature sensor based on identical fiber Bragg grating according to claim 1, characterized in that: The temperature sensor based on the identical fiber Bragg grating further includes: a circulator; The first port of the circulator is connected to a broadband light source through an optical fiber, the second port of the circulator is connected to an isotropic weak-reflection fiber Bragg grating sensor array, and the third port of the circulator is connected to an input end of a signal demodulation module through a waveguide.

7. A temperature detection system, characterized in that: The temperature detection system comprises a temperature sensor based on an identical fiber Bragg grating and a photodetector according to any one of claims 1 to 6; The photoelectric detector is connected to the temperature sensor based on the identical fiber Bragg grating through an optical fiber, and is used for converting the optical signal demodulated by the temperature sensor based on the identical fiber Bragg grating into an electrical signal.

8. The temperature detection system according to claim 7, characterized in that: The temperature detection system further includes: a warning device; The warning device is electrically connected to the photoelectric detector and is used to receive the electrical signal sent by the photoelectric detector and perform segmented real-time temperature measurement and early warning.

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