CN213874715U - Optical fiber temperature sensor - Google Patents

Optical fiber temperature sensor Download PDF

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CN213874715U
CN213874715U CN202120011544.3U CN202120011544U CN213874715U CN 213874715 U CN213874715 U CN 213874715U CN 202120011544 U CN202120011544 U CN 202120011544U CN 213874715 U CN213874715 U CN 213874715U
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fiber
optical fiber
single mode
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temperature sensor
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刘德军
李伟
王鹏飞
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Shenzhen University
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Abstract

The utility model discloses an optical fiber temperature sensor, including first optical fiber jumper wire, first single mode fiber, tubulose hollow optic fibre, second single mode fiber and second optical fiber jumper wire, the one end of first optical fiber jumper wire is connected first single mode fiber's input, first single mode fiber's output with the input of tubulose hollow optic fibre is connected, the output of tubulose hollow optic fibre with the input of second single mode fiber is connected, the output of second single mode fiber with the input of second optical fiber jumper wire is connected, tubulose hollow optic fibre includes the air core and the cladding is in the outer quartz covering of air core, the diameter of air core is 5-12 microns. The utility model discloses utilize mach-zehnder to interfere and anti-resonance effect stack, realize meeting an emergency, crooked and twist reverse insensitive temperature sensing measurement, effectively solved the cross sensitive problem of many parameters among the temperature measurement.

Description

Optical fiber temperature sensor
Technical Field
The utility model relates to an optical fiber sensing technical field, in particular to optical fiber temperature sensor.
Background
Temperature has always been one of the most interesting key physical parameters, and temperature measurement plays an important role in the fields of civil engineering, petrochemical engineering, electrical engineering, bioengineering, mechanical engineering and the like. Compared with the traditional sensor based on electronic or mechanical motion, the optical fiber temperature sensor has become a hotspot of current sensor research due to the advantages of high sensitivity, corrosion resistance, simple structure, good explosion-proof performance, good light guiding performance, flexibility, electromagnetic interference resistance, good insulativity, convenience for multiplexing, convenience for forming a net, low cost and the like.
Over the past decades, many fiber configurations for temperature measurement have been proposed by experts, such as Fiber Bragg Gratings (FBGs), fabry-perot interferometers (FPIs), mach-zehnder interferometers (MZIs), and Sagnac Interferometers (SIs). The MZI fiber temperature sensor has been widely studied due to its relatively simple structure and high sensitivity, but it is worth noting that this type of fiber temperature sensor has high cross-sensitivity to a plurality of environmental variables such as strain, bending, torsion, etc. With the expansion of the application field of the optical fiber temperature sensor, the application scene is more complex, the cross influence of a plurality of environment variables seriously reduces the reliability and the detection precision of the sensor, and for example, in the real-time temperature monitoring of cables, multivariable crosstalk such as strain, bending, torsion and the like becomes a prominent problem.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing an optic fibre temperature sensor solves optic fibre temperature sensor to meeting an emergency, crooked and torsional cross sensitive problem.
The embodiment of the utility model provides an optical fiber temperature sensor, including first optical fiber jumper wire, first single mode fiber, tubulose hollow optic fibre, second single mode fiber and second optical fiber jumper wire, the one end of first optical fiber jumper wire is connected first single mode fiber's input, first single mode fiber's output with the input of tubulose hollow optic fibre is connected, the output of tubulose hollow optic fibre with second single mode fiber's input is connected, second single mode fiber's output with the input of second optical fiber jumper wire is connected, tubulose hollow optic fibre includes air core and cladding quartz covering outside the air core, the diameter of air core is 5-12 microns.
Furthermore, the first single-mode fiber and the second single-mode fiber both comprise a fiber core and a quartz cladding coated outside the fiber core.
Furthermore, the diameters of fiber cores of the first single-mode fiber and the second single-mode fiber are both 8-10 micrometers.
Further, the quartz cladding diameters of the first single mode fiber and the second single mode fiber are both 125 micrometers.
Further, the refractive index of the fiber core of the first single-mode fiber is greater than the refractive index of the quartz cladding of the first single-mode fiber, and the refractive index of the fiber core of the second single-mode fiber is greater than the refractive index of the quartz cladding of the second single-mode fiber.
Further, the diameters of the fiber cores of the first single-mode fiber and the second single-mode fiber are both 8.6 microns.
Further, the length of the tubular hollow-core optical fiber is 600-1000 microns.
Further, the tubular hollow-core optical fiber has a length of 707 μm.
Further, the diameter of the air core is 10 microns.
Further, the diameter of the quartz cladding of the tubular hollow-core optical fiber is 126 micrometers.
The embodiment of the utility model provides an optical fiber temperature sensor, including first optical fiber jumper wire, first single mode fiber, tubulose hollow optic fibre, second single mode fiber and second optical fiber jumper wire, the one end of first optical fiber jumper wire is connected first single mode fiber's input, first single mode fiber's output with the input of tubulose hollow optic fibre is connected, the output of tubulose hollow optic fibre with second single mode fiber's input is connected, second single mode fiber's output with the input of second optical fiber jumper wire is connected, tubulose hollow optic fibre includes air core and cladding quartz covering outside the air core, the diameter of air core is 5-12 microns. The utility model discloses utilize mach-zehnder to interfere structure and anti-resonance effect stack, can realize meeting an emergency, crooked and twist reverse insensitive temperature sensing measurement, effectively solved the cross sensitive problem of many parameters among the temperature measurement.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without any creative effort.
Fig. 1 is a schematic structural diagram of an optical fiber temperature sensor according to an embodiment of the present invention;
fig. 2 is a schematic view of light propagation of an optical fiber temperature sensor according to an embodiment of the present invention;
fig. 3 is a transmission spectrum diagram detected by a spectrometer under different temperature, strain, bending and torsion conditions when the length of the tubular hollow-core optical fiber of the optical fiber temperature sensor provided by the embodiment of the present invention is 707 microns;
fig. 4 is a graph illustrating the shift of the resonant wavelength under different temperature, strain, bending and torsion conditions when the length of the tubular hollow-core optical fiber of the optical fiber temperature sensor provided by the embodiment of the present invention is 707 microns.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, of the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
It will be understood that the terms "comprises" and/or "comprising," when used in this specification and the appended claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It is also to be understood that the terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
It should be further understood that the term "and/or" as used in the specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.
Referring to fig. 1, fig. 1 is a schematic structural diagram of an optical fiber temperature sensor according to an embodiment of the present invention. As shown in the figure, optical fiber temperature sensor includes first optical fiber jumper 1, first single mode fiber 2, tubulose hollow optic fibre 4, second single mode fiber 6 and second optical fiber jumper 7, and the one end of first optical fiber jumper 1 is connected with first single mode fiber 2's input, and first single mode fiber 2's output is connected with tubulose hollow optic fibre 4's input, and tubulose hollow optic fibre 4's output is connected with second single mode fiber 6's input, and second single mode fiber 6's output is connected with second optical fiber jumper 7's input.
As shown in fig. 1 and 2, the first single-mode fiber 2 and the second single-mode fiber 6 are the same type of common single-mode fiber, and both the first single-mode fiber 2 and the second single-mode fiber 6 include a fiber core 8 and a first silica cladding 9 covering the fiber core 8. In a preferred embodiment, the core 8 is about 8.6 microns in diameter and is made of a doped silica material; the first quartz cladding 9 is about 125 microns in diameter and the material is higher purity quartz. Wherein the refractive index of the core 8 is greater than the refractive index of the first silica cladding 9. The polymer coating outside the hollow-core optical fiber is removed at high temperature, then the first single-mode optical fiber 2 is coaxially connected with the tubular hollow-core optical fiber 4, the output end of the first single-mode optical fiber 2 and the input end of the tubular hollow-core optical fiber 4 are used as a first welding point 3, the first single-mode optical fiber 2 and the tubular hollow-core optical fiber 4 are welded at the first welding point 3 by using a welding machine, a first quartz cladding 9 is aligned to a second quartz cladding 11 during welding, the discharge power of the welding machine is standard-75 bit, the discharge time is 600 milliseconds, and the end face interval between the first single-mode optical fiber 2 and the tubular hollow-core optical fiber 4 is 12 micrometers. The output end of the tubular hollow-core optical fiber 4 and the input end of the second single-mode optical fiber 6 are used as the second welding point 5, and the welding method is the same as that of the first welding point 3, and the details are not repeated here.
As shown in the model of CAP010/150/24T of the tubular hollow-core optical fiber 4 in FIG. 1, the tubular hollow-core optical fiber 4 is composed of an air core 10 and a second quartz cladding 11 coated outside the air core 10. Wherein the diameter of the air core 10 is 10 microns and the diameter of the second silica cladding is 126 microns. The user can obtain a specified length of the tubular hollow-core fiber 4 by using a fiber cutter.
As shown in fig. 2, when the optical fiber temperature sensor of the present application operates, a broad spectrum light is introduced into the first optical fiber jumper 1, the broad spectrum light enters the first single-mode optical fiber 2 from the first optical fiber jumper 1, enters the tubular hollow-core optical fiber 4 at the first fusion-splicing point 3, and enters the air core 10 of the hollow-core optical fiber for propagation, and because the mode fields of the single-mode optical fiber and the tubular hollow-core optical fiber 4 are not matched, a part of the broad spectrum light enters the second quartz cladding 11 of the tubular hollow-core optical fiber 4 for transmission. The wide-spectrum light propagating in the air core 10 and the second quartz cladding 11 is coupled to the second fusion point 5 to form a mach-zehnder interference effect. In addition, in combination with the external air, the tubular hollow-core optical fiber 4 is equivalent to a structure in which two layers of air sandwich the second silica cladding 11, that is, a three-layer structure of air-second silica cladding 11-air, when the wide-spectrum light is transmitted to the interface of the air core 10 and the second silica cladding 11, the wide-spectrum light satisfying the resonance condition is transmitted from the second silica cladding 11 into the external air, and the light satisfying the anti-resonance condition is transmitted in the air core 10, that is, the anti-resonance effect occurs. Light output from the tubular hollow-core optical fiber 4 is coupled through a second fusion point 5 to generate composite light, the composite light is output to a second single-mode optical fiber 6, and finally the composite light is input to a spectrometer through a second optical fiber jumper 7. The spectrometer displays the transmission spectrum of the sensing structure, and causes mode coupling in the tubular hollow optical fiber 4 to change along with changes of the external environment of the sensor, such as temperature, strain, bending or torsion, so that wavelength drift of interference wave troughs in the transmission spectrum is caused, the wavelength drift amount and each change parameter generate a one-to-one mapping relation, and the change of the environment parameter can be known by observing the change of the positions of the interference wave troughs.
As shown in fig. 3 and 4, when the length of the tubular hollow-core optical fiber 4 is 707 μm, the interference trough of the superimposed light transmission spectrum moves in the long-wavelength direction with the rise of the temperature; each interference trough is nearly insensitive when strain, curvature or torsion is applied.
Figure BDA0002883849570000051
TABLE 1
As shown in Table 1, Table 1 shows the sensitivity of the optical fiber temperature sensor to the temperature corresponding to the interference trough and the linear fitting coefficient (R) thereof when the tubular hollow-core optical fiber is 707 microns long (S-707)2) Since the amount of movement of the interference trough is small and not linear with the amount of change in strain, bending and torsion, the standard deviation (std (pm)) is used herein to represent the sensitivity of the sensor to strain, bending and torsion. When the length of the tubular hollow-core optical fiber is 707 microns, the corresponding sensitivity of the tubular hollow-core optical fiber is obtained by measuring the drift amount of interference wave troughs of transmission spectrums of environmental changes such as temperature, strain, bending and torsion through a spectrometer; the corresponding temperature sensitivity of 31.6 pm/DEG C is obtained by fitting the wavelength drift at the trough of 1584.8nm (dip1), the standard deviation of the interference trough in the range of 0-3000 mu epsilon is 13pm, and the standard deviation is 0-5.48m-1The standard deviation of the interference valleys in the bending range was 50pm, and the standard deviation of the interference valleys in the 0-90 ° range was 59 pm. Therefore, the sensor shows high sensitivity to temperature, and variables such as strain, bending and torsion have little influence on the sensor.
The embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, the present invention can be further modified and modified, and such modifications and modifications also fall within the protection scope of the appended claims.
It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Claims (10)

1. The utility model provides an optical fiber temperature sensor, includes first optical fiber jumper wire, first single mode fiber, tubulose hollow optic fibre, second single mode fiber and second optical fiber jumper wire, the one end of first optical fiber jumper wire is connected first single mode fiber's input, first single mode fiber's output with the input of tubulose hollow optic fibre is connected, the output of tubulose hollow optic fibre with second single mode fiber's input is connected, second single mode fiber's output with the input of second optical fiber jumper wire is connected, tubulose hollow optic fibre includes air core and cladding quartz cladding outside the air core, the diameter of air core is 5-12 microns.
2. The fiber optic temperature sensor of claim 1, wherein the first and second single mode fibers each comprise a fiber core and a silica cladding surrounding the fiber core.
3. The fiber optic temperature sensor of claim 2, wherein the first and second single mode fibers each have a core diameter of 8-10 microns.
4. The fiber optic temperature sensor of claim 2, wherein the silica cladding diameters of the first and second single mode fibers are both 125 microns.
5. The fiber optic temperature sensor of claim 2, wherein the refractive index of the core of the first single mode fiber is greater than the refractive index of the silica cladding of the first single mode fiber, and the refractive index of the core of the second single mode fiber is greater than the refractive index of the silica cladding of the second single mode fiber.
6. The fiber optic temperature sensor of claim 2, wherein the first and second single mode fibers each have a core diameter of 8.6 microns.
7. The fiber optic temperature sensor of claim 1, wherein the tubular hollow-core fiber has a length of 600 and 1000 microns.
8. The fiber optic temperature sensor of claim 7, wherein the tubular hollow-core fiber has a length of 707 microns.
9. The fiber optic temperature sensor of claim 1, wherein the air core has a diameter of 10 microns.
10. The fiber optic temperature sensor of claim 1, wherein the quartz cladding of the tubular hollow-core fiber has a diameter of 126 microns.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114486766A (en) * 2022-02-09 2022-05-13 深圳大学 Optical fiber humidity sensor with temperature calibration function

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114486766A (en) * 2022-02-09 2022-05-13 深圳大学 Optical fiber humidity sensor with temperature calibration function
WO2023151112A1 (en) * 2022-02-09 2023-08-17 深圳大学 Optical fiber humidity sensor having temperature calibration capability

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