CN114414085A - Optical fiber temperature sensor - Google Patents
Optical fiber temperature sensor Download PDFInfo
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- CN114414085A CN114414085A CN202210041057.0A CN202210041057A CN114414085A CN 114414085 A CN114414085 A CN 114414085A CN 202210041057 A CN202210041057 A CN 202210041057A CN 114414085 A CN114414085 A CN 114414085A
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- optical fiber
- temperature sensor
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 52
- 239000000835 fiber Substances 0.000 claims abstract description 45
- 239000000463 material Substances 0.000 claims abstract description 32
- 238000005253 cladding Methods 0.000 claims abstract description 11
- 230000003287 optical effect Effects 0.000 claims abstract description 8
- 239000004205 dimethyl polysiloxane Substances 0.000 claims description 6
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 claims description 6
- -1 polydimethylsiloxane Polymers 0.000 claims description 5
- 238000001514 detection method Methods 0.000 abstract description 15
- 239000002131 composite material Substances 0.000 abstract description 9
- 230000008859 change Effects 0.000 abstract description 8
- 230000008901 benefit Effects 0.000 abstract description 6
- 230000035945 sensitivity Effects 0.000 abstract description 5
- 238000009529 body temperature measurement Methods 0.000 abstract description 2
- 238000000034 method Methods 0.000 abstract description 2
- 238000010884 ion-beam technique Methods 0.000 description 7
- 235000013870 dimethyl polysiloxane Nutrition 0.000 description 5
- 229910000510 noble metal Inorganic materials 0.000 description 5
- 239000004038 photonic crystal Substances 0.000 description 5
- 238000002360 preparation method Methods 0.000 description 5
- 238000003801 milling Methods 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- CXQXSVUQTKDNFP-UHFFFAOYSA-N octamethyltrisiloxane Chemical compound C[Si](C)(C)O[Si](C)(C)O[Si](C)(C)C CXQXSVUQTKDNFP-UHFFFAOYSA-N 0.000 description 2
- 238000004987 plasma desorption mass spectroscopy Methods 0.000 description 2
- 229910052594 sapphire Inorganic materials 0.000 description 2
- 239000010980 sapphire Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000000985 reflectance spectrum Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
Images
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Temperature Or Quantity Of Heat (AREA)
Abstract
The invention relates to the technical field of temperature measurement, in particular to an optical fiber temperature sensor, which comprises: the optical fiber sensing component comprises an optical fiber and a thermal expansion material, one end of the optical fiber sensing component is connected with the light source and the optical detector through the circulator, the fiber core protrudes out of the cladding at the other end of the optical fiber sensing component, a gap is arranged in the fiber core, the fiber core is divided into a first extending portion and a second extending portion through the gap, and the thermal expansion material fills the gap. When in application, the invention is placed in an environment to be tested; the light emitted by the light source is transmitted to the composite structure formed by the first extending part, the second extending part and the thermal expansion material along the optical fiber; temperature detection is achieved by a change in reflected light detected by the light detector. The invention has the advantages of high temperature detection sensitivity, simple process, low cost and the like, and has good application prospect in the field of optical fiber temperature sensing.
Description
Technical Field
The invention relates to the technical field of temperature measurement, in particular to an optical fiber temperature sensor.
Background
The optical fiber temperature sensor has the advantages of small size, high response speed, electromagnetic interference resistance and the like, thereby being widely concerned. Researchers have developed optical fiber temperature sensors of different structures and operating principles, e.g., based on fiber bragg gratings, long-period fiber gratings, fabry-perot interferometric cavities, photonic crystal fibers, etc.
For the temperature sensor of the fiber grating, it is common that the temperature changes the period of the fiber grating, thereby changing the center wavelength of the fiber grating, and the temperature sensing is realized by measuring the shift of the center wavelength, for example, patent CN 111982169A.
For the temperature sensor of the fabry-perot interference cavity, the fabry-perot interference cavity is usually arranged at the end of an optical fiber, and temperature detection is realized through the change of the length of the interference cavity. For example, patent CN109580035A discloses a high-fringe-contrast sapphire fiber fabry-perot high-temperature sensor, in which a first beam of reflected light generated on two surfaces of an interference cavity and a first beam of reflected light are coupled into a sapphire fiber to form a fabry-perot interference signal, and the interference signal is demodulated by a spectrum method to obtain a fabry-perot optical path difference, so as to reversely deduce the temperature.
For the temperature sensor based on the photonic crystal fiber, it is common to place the temperature-sensitizing layer on the outer surface of the photonic crystal, and two transmission fibers are used to connect with the photonic crystal fiber, for example, patent CN 108225600A.
In the prior art, the cost of the fiber grating and the photonic crystal fiber is high, and the sensitivity is low. The optical fiber sensor based on the Fabry-Perot interference cavity is complex to manufacture and high in cost.
Disclosure of Invention
In order to solve the above problems, the present invention provides an optical fiber temperature sensor, including: the optical fiber sensing component comprises an optical fiber and a thermal expansion material, one end of the optical fiber sensing component is connected with the light source and the optical detector through the circulator, the fiber core protrudes out of the cladding at the other end of the optical fiber sensing component, a gap is arranged in the fiber core, the fiber core is divided into a first extending portion and a second extending portion through the gap, and the thermal expansion material fills the gap.
Further, the first and second extensions have a length greater than 1 micron and less than 10 microns.
Further, the optical fiber is a single mode optical fiber.
Further, the width of the slit is less than 100 nanometers.
Further, the thermal expansion material is polydimethylsiloxane.
Further, the first extension has a thickness greater than a thickness of the second extension.
Furthermore, at the bottom of the gap, the gap is narrow; at the end of the slit, the slit is wide.
Further, the optical fiber is a multimode optical fiber.
Further, the light source is a broadband light source.
Still further, the light detector comprises a spectrometer.
The invention has the beneficial effects that: the invention provides an optical fiber temperature sensor, comprising: the optical fiber sensing component comprises an optical fiber and a thermal expansion material, one end of the optical fiber sensing component is connected with the light source and the optical detector through the circulator, the fiber core protrudes out of the cladding at the other end of the optical fiber sensing component, a gap is arranged in the fiber core, the fiber core is divided into a first extending portion and a second extending portion through the gap, and the thermal expansion material fills the gap. When in application, the invention is placed in an environment to be tested; the light emitted by the light source is transmitted to the composite structure formed by the first extending part, the second extending part and the thermal expansion material along the optical fiber; the thermal expansion material absorbs heat and expands to change the distance between the first extending part and the second extending part, so that the reflection characteristic of the composite structure is changed, and temperature detection is realized through the change of reflected light detected by the light detector. In the present invention, the thermal expansion material changes the distance between the first extension portion and the second extension portion after thermally expanding, and the present invention has an advantage of high temperature detection sensitivity because the light reflection characteristic of the composite structure is very sensitive to the structure, particularly, the distance between the first extension portion and the second extension portion. During preparation, a gap can be prepared in the fiber core by using focused ion beam milling, and the thermal expansion material can be arranged in the gap by arranging the first extending part and the second extending part in the thermal expansion material. Therefore, the preparation process is simple and the cost is low.
The present invention will be described in further detail below with reference to the accompanying drawings.
Drawings
FIG. 1 is a schematic diagram of an optical fiber sensing component.
FIG. 2 is a schematic view of yet another fiber optic sensing component.
FIG. 3 is a schematic view of yet another fiber optic sensing component.
FIG. 4 is a schematic view of yet another fiber optic sensing component.
In the figure: 1. a fiber core; 2. a cladding layer; 3. a thermally expansive material; 11. a first extension; 12. a second extension.
Detailed Description
In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.
Example 1
The invention provides an optical fiber temperature sensor which comprises a light source, a light detector, a circulator and an optical fiber sensing component. As shown in fig. 1, the optical fiber sensing part includes an optical fiber and a thermal expansion material 3. One end of the optical fiber sensing component is connected with the light source and the optical detector through the circulator; at the other end of the fiber sensing element, the core 1 protrudes from the cladding 2. That is, the cladding 2 and the coating are removed from the core 1 at the other end of the fiber sensing. In practical applications, it is also possible to remove only the coating layer, with the key being to reduce the diameter of the fiber so that it becomes thinner. The core 1 is provided with a slit that divides the core into a first extension 11 and a second extension 12. The first extension 11 and the second extension 12 are connected to the core 1 at the root. The thermal expansion material 3 fills the gap. The width of the gap is less than 100 nanometers. The thermal expansion material 3 is polydimethylsiloxane, i.e., PDMS. The polydimethylsiloxane has high transparency, and the light transmittance is almost 100%; good thermal conductivity, i.e., a thermal conductivity of 0.134-0.159W/(m. K), and good chemical stability and high thermal expansion coefficient, which are very suitable for the application of the present invention. In this embodiment, the optical fiber is a single mode fiber having a small core 1 diameter. After providing the slit in the optical fiber, the first extension 11 and the second extension 12 each have a small width, and thus the distance between the first extension 11 and the second extension 12 has a greater influence on the light reflection characteristics of the composite structure.
In this embodiment, the light source is monochromatic light, and the light detector does not include a spectrometer. The light source emits monochromatic light, the monochromatic light passes through the circulator and the optical fiber and then reaches the composite structure formed by the first extending part 11, the second extending part 12 and the thermal expansion material 3, and the composite structure reflects the monochromatic light back to the optical fiber and then reaches the optical detector through the circulator. The thermal expansion material 3 absorbs heat and expands to change the distance between the first extension part 11 and the second extension part 12, so that the coupling between the first extension part 11 and the second extension part 12 is changed, the reflection of the composite structure to monochromatic light is changed, and the temperature detection is realized by detecting the intensity change of the reflected light. The embodiment applies monochromatic light, does not need to be applied to a spectrometer, and is low in cost.
In the present invention, the thermally expansible material 3 changes the distance between the first extension portion 11 and the second extension portion 12 after thermally expanding, and the present invention has an advantage of high temperature detection sensitivity because the light reflection characteristic of the composite structure is very sensitive to the structure, particularly, the distance between the first extension portion 11 and the second extension portion 12. In preparation, a slot is prepared in the core 1 by applying focused ion beam milling, and the thermally expansible material 3 is arranged in the slot by placing the first extension 11 and the second extension 12 in the thermally expansible material 3. Therefore, the preparation process is simple and the cost is low.
In the present invention, the ion source emits an ion beam during preparation of the slit, and the ion beam is accelerated and focused to irradiate the surface of the core 1. The ion beam has a high energy, and the ion beam collides with the core 1 material, so that the core 1 material is sputter-stripped, thereby forming a gap. The gap prepared by ion beam milling has the advantages of high precision and high resolution, and is convenient to apply in the invention.
Example 2
In embodiment 1, as shown in fig. 1, the first extension portion 11 and the second extension portion 12 are equal in length. The first and second extensions 11, 12 have a length greater than 1 micron and less than 10 microns to facilitate formation of a resonant cavity within the first and second extensions 11, 12. On the right side of fig. 1, when light is transmitted from the core 1 into the first and second extensions 11 and 12. Reflection is formed at the right end surfaces of the first extension portion 11 and the second extension portion 12, and resonance is formed in the first extension portion 11 and the second extension portion 12. The width of the slot and the refractive index of the PDMS in the slot change, changing the resonance wavelength in the first extension 11 and the second extension 12. Temperature detection is achieved by a change in the resonance wavelength in the first extension 11 and the second extension 12. In this embodiment, the light source is a broadband light source; the light detector includes a spectrometer for detecting the reflectance spectrum.
Example 3
In example 2, as shown in fig. 2, the thickness of the first extension portion 11 is larger than the thickness of the second extension portion 12. That is, the first extension 11 is thick and the second extension 12 is thin. Thus, the resonance wavelength in the first extension section 11 is different from the resonance wavelength in the second extension section 12. In the reflection spectrum, two reflection resonance wavelengths are provided, and the temperature of the environment to be measured can be determined through the movement of the two resonance wavelengths. Compared with the embodiment 2, the resonant cavities with two different shapes or sizes in the embodiment 3 can realize resonance under two conditions, the temperature of the environment to be measured is determined through the resonance under the two conditions, and the resonant cavity has the advantage of high result accuracy. In addition, since the first extension part 11 and the second extension part 12 have different thicknesses and different resonance wavelengths, the two resonance wavelengths are different in moving condition when the temperature changes, and the temperature of the environment to be measured can be determined by the difference between the two resonance wavelengths.
Example 4
On the basis of example 3, as shown in fig. 3, at the bottom of the slit, the slit is narrow; at the end of the slit, the slit is wide. That is, at the root of the slit, the first extension 11 and the second extension 12 are thick. As a result, on the one hand, the first extension 11 and the second extension 12 can be connected to the core 1 more firmly; on the other hand, it is advantageous that the light in the core 1 is transmitted to the first extension 11 and the second extension 12 more, and the intensity of the reflected light is made greater, which facilitates detection. In particular, the first and second extensions 11, 12 are bifurcated at the base of the slot, i.e. the slot intersects at a point at the base of the slot, which allows more light in the core 1 to be coupled into the first and second extensions 11, 12. When the thermal expansion material 3 absorbs heat and expands, the first extension portion 11 and the second extension portion 12 are less likely to be significantly deformed at the base, and the connection between the first extension portion 11 and the second extension portion 12 and the core 1 is broken.
Example 5
On the basis of examples 1-4, the bottom of the slot is outside the cladding 2, as shown in fig. 4. That is, in fig. 4, the bottom of the slit is on the right side of the end face of the cladding 2, and the cladding 2 does not cover the slit. Due to the absence of the coating of the cladding 2, when the thermally-expansible material 3 in the slit absorbs heat to expand, the relative position between the first elongated portion 11 and the second elongated portion 12 changes more, and the resonance wavelength in the first elongated portion 11 and the second elongated portion 12 changes more, thereby achieving higher-sensitivity temperature detection.
Further, the end surfaces of the first extended portion 11 and the second extended portion 12 are provided with noble metal films. That is, in fig. 4, the noble metal films are provided on the right-side end surfaces of the first extension portion 11 and the second extension portion 12. The noble metal film is made of gold. The thickness of the noble metal film is more than 40 nanometers. The noble metal film can improve the reflection coefficient of the end surfaces of the first extending part 11 and the second extending part 12, so that a stronger optical field is formed in the first extending part 11 and the second extending part 12, the resonance wavelength is easier to determine in a reflection spectrum, the detection difficulty is reduced, the half-peak width of a signal is reduced, and the temperature detection sensitivity is improved.
Furthermore, the optical fiber is a multimode optical fiber, so that the processing difficulty is reduced. In addition, the multimode fiber also improves various application modes for the device. For example, first, a base film is fed into the optical fiber, and the base film also enters the first extension portion 11 and the second extension portion 12, and the base film also reflects light; then, a higher-order mode is input in the optical fiber, and due to the difference in the sectional dimensions of the first elongated portion 11 and the second elongated portion 12, the modes entering the first elongated portion 11 and the second elongated portion 12 are significantly different, and the resonance wavelength in the first elongated portion 11 and the second elongated portion 12 is greatly different. Thus, the optical fiber sensing component can be applied in various situations, and the detection results are compared, so that the temperature detection accuracy is high.
In the present invention, the thermal expansion material 3 is provided in the gap, and the thermal expansion material 3 not only changes the coupling between the first elongated portion 11 and the second elongated portion 12, but also pulls the first elongated portion 11 and the second elongated portion 12 when the thermal expansion material 3 expands, so that the first elongated portion 11 and the second elongated portion 12 are elongated, thereby changing more the cavity length of the resonant cavity formed in the first elongated portion 11 and the second elongated portion 12, thereby changing more the resonant wavelength, thereby achieving more sensitive temperature detection.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.
Claims (10)
1. A fiber optic temperature sensor, comprising: the optical fiber sensing component comprises an optical fiber and a thermal expansion material, one end of the optical fiber sensing component is connected with the light source and the optical detector through the circulator, the fiber core protrudes out of the cladding at the other end of the optical fiber sensing component, a gap is arranged in the fiber core, the fiber core is divided into a first extending part and a second extending part through the gap, and the thermal expansion material fills the gap.
2. The fiber optic temperature sensor of claim 1, wherein: the first and second extensions have a length greater than 1 micron and less than 10 microns.
3. The fiber optic temperature sensor of claim 1, wherein: the optical fiber is a single mode optical fiber.
4. The fiber optic temperature sensor of claim 1, wherein: the width of the gap is less than 100 nanometers.
5. The fiber optic temperature sensor of claim 1, wherein: the thermal expansion material is polydimethylsiloxane.
6. The fiber optic temperature sensor of claim 1, wherein: the first extension has a thickness greater than a thickness of the second extension.
7. The fiber optic temperature sensor of claim 1, wherein: at the bottom of the gap, the gap is narrow; at the ends of the slit, the slit is wide.
8. The fiber optic temperature sensor of claim 1, wherein: the optical fiber is a multimode optical fiber.
9. The fiber optic temperature sensor of any of claims 1-8, wherein: the light source is a broadband light source.
10. The fiber optic temperature sensor of claim 9, wherein: the light detector comprises a spectrometer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210041057.0A CN114414085A (en) | 2022-01-14 | 2022-01-14 | Optical fiber temperature sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210041057.0A CN114414085A (en) | 2022-01-14 | 2022-01-14 | Optical fiber temperature sensor |
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| Publication Number | Publication Date |
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| CN114414085A true CN114414085A (en) | 2022-04-29 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210041057.0A Withdrawn CN114414085A (en) | 2022-01-14 | 2022-01-14 | Optical fiber temperature sensor |
Country Status (1)
| Country | Link |
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| CN (1) | CN114414085A (en) |
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2022
- 2022-01-14 CN CN202210041057.0A patent/CN114414085A/en not_active Withdrawn
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Application publication date: 20220429 |
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