CN211824859U - Optical fiber air pressure sensor based on dislocation fusion and vernier effect - Google Patents
Optical fiber air pressure sensor based on dislocation fusion and vernier effect Download PDFInfo
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- CN211824859U CN211824859U CN201922227916.1U CN201922227916U CN211824859U CN 211824859 U CN211824859 U CN 211824859U CN 201922227916 U CN201922227916 U CN 201922227916U CN 211824859 U CN211824859 U CN 211824859U
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Abstract
The invention provides an optical fiber air pressure sensor based on dislocation fusion and vernier effect. This sensor includes single mode fiber, hollow optic fibre and suspension core optic fibre, and the both ends of hollow optic fibre carry out the butt fusion with single mode fiber and suspension core optic fibre respectively, in order to obtain the interference spectrum of higher contrast, suspension core optic fibre carries out the dislocation butt fusion with hollow optic fibre, and the suspension core optic fibre other end communicates with each other with the atmosphere to guarantee that gas freely advances out sensing head. The hollow core optical fiber and the suspension core optical fiber form two cascaded Fabry-Perot interferometers, and the optical path difference of the two interferometers is similar but unequal, so that the optical vernier effect is generated, and the sensitivity of air pressure is effectively improved. The utility model has the advantages of small, easily operation, sensitivity height, have wide application prospect.
Description
Technical Field
The invention relates to an optical fiber air pressure sensor based on dislocation fusion and vernier effect, and belongs to the field of optical fiber air pressure sensing.
Background
The optical fiber has a great role in optics, and the appearance of the optical fiber makes great progress in the fields of sensing, communication and the like. The optical fiber sensing technology starts in the 70 th 20 th century, and the optical fiber sensor has the advantages of small size, light weight, electromagnetic interference resistance, high measurement precision, convenience in realizing a distributed sensor and the like, and is continuously developed and innovated in various scientific research fields. The measurement of air pressure is particularly important in industrial production process, pipeline interior, environmental monitoring and other tests, and in the currently adopted technology, the selection of some materials is relatively complex in the manufacturing process, poor in controllability and high in process requirement. There are also problems with some air pressure sensors resulting in reduced sensitivity. The Fabry-Perot interferometer has similar but unequal optical path difference between the two interferometer resonant cavities, so that optical vernier effect is produced and sensitivity is greatly raised. The method is widely applied to the fields of optical fiber communication and optical fiber sensing. The structure is compact, the manufacture is simple, and the cost is low. Thereby allowing the replacement of many expensive and complex materials and achieving relatively better results.
Disclosure of Invention
The invention aims to solve the problems of low precision, low sensitivity and complex structure of the existing air pressure sensor, and provides an optical fiber air pressure sensor based on dislocation welding and vernier effect.
The sensing head (4) of the optical fiber air pressure sensor based on the dislocation fusion and the vernier effect comprises a single-mode optical fiber (31), a hollow-core optical fiber (32) and a suspension core optical fiber (33); the optical fiber splicing method comprises the steps of firstly, welding a hollow core optical fiber (32) and a single mode optical fiber (31) to form a first reflecting surface (311), then, welding the other end of the hollow core optical fiber (32) and a suspension core optical fiber (33) to form a second reflecting surface (312), and in order to guarantee the consistency of optical paths, dislocation welding is needed to be carried out on the suspension core optical fiber (33), the other end of the suspension core optical fiber (33) is connected with air, and a third reflecting surface (313) is formed. Wherein, the reflecting surface M1(311) and the reflecting surface M2(312) form an air Fabry-Perot (FP) cavity with a length L1(321) A quartz FP cavity consisting of reflecting surfaces M2(312) and M3(313) and having a length L2(322) Because the optical path difference of the air FP cavity and the quartz FP cavity is approximately equal, an optical vernier effect is generated, and an optical fiber air pressure sensing head with the vernier effect is further formed.
When the intracavity air pressure P of the sensing head (4) of the optical fiber air pressure sensor based on dislocation fusion and vernier effect changes, the refractive index n in the cavity is changed, the variation at the moment is delta n, and then the interference envelope is translated, and the translation amount is delta s at the moment.
An optical signal emitted by the broadband light source (1) enters the sensing head (4) through the circulator (2), incident light sequentially passes through the three reflecting surfaces, and part of the incident light is reflected back due to the mismatch of the refractive indexes of the reflecting surfaces. Therefore, the first reflecting surface (311) and the second reflecting surface (312) form an air cavity with a length L1(321) (ii) a The second reflecting surface (312) and the third reflecting surface (313) form a quartz cavity with a length L2(322). Wherein the complex amplitude of the light reflected by the first reflecting surface (311) is E1The complex amplitude of light reflected from the second reflecting surface (312) is E2The complex amplitude of light reflected by the third reflecting surface (313) is E3. Reflected light E1、E2And E3The interference occurs, and the interference is received by the spectrometer (3) through the circulator (2) to display the interference spectrum of the sensor.
The preset temperature of the optical fiber air pressure sensor based on the dislocation fusion and the vernier effect is T-22 ℃.
The relation formula between the air pressure in the cavity of the sensing head (4) of the optical fiber air pressure sensor based on the dislocation welding and the vernier effect and the refractive index is as follows:
the relation formula of the intracavity refractive index change delta n and the interference spectrum translation delta s of the sensing head (4) of the optical fiber air pressure sensor based on the dislocation fusion and the vernier effect is as follows:
Δn＝α·Δs
in the formula, α is a predetermined constant, and can be set according to an empirical value.
Drawings
Fig. 1 is a diagram of the experimental device of the present invention.
Fig. 2 is a schematic diagram of a sensor.
Detailed Description
In order to more clearly and concisely illustrate features not described in detail, related fabrication/processing steps and limitations of the specific implementation, an embodiment of the fiber optic air pressure sensor based on the mis-fusion and vernier effect will be described below with reference to fig. 1 and 2.
The optical fiber air pressure sensor based on dislocation fusion and vernier effect comprises a broadband light source (1), a circulator (2), a spectrometer (3) and a sensing head (4), wherein:
the sensing head (4) is composed of a single-mode optical fiber (31), a hollow-core optical fiber (32) and a suspension core optical fiber (33); carry out the butt fusion with hollow core optic fibre (32) and single mode fiber (31), form first plane of reflection (311), the other end carries out the butt fusion with suspension core optic fibre (33), form second plane of reflection (312), form third plane of reflection (313) between suspension core optic fibre (33) end and the air, it is unanimous with the light path in single mode fiber (31) to guarantee the light that suspension core optic fibre (33) reflect back, obtain the interference spectrum of higher contrast promptly, need carry out dislocation butt fusion with suspension core optic fibre (33) and hollow core optic fibre (32), keep the two fibre cores at same horizontal line, and suspension core optic fibre (33) the other end links to each other with the air, can guarantee that gaseous free business turn over head (4).
The light signal that broadband light source (1) sent advances sensing head (4) through circulator (2), and incident light can pass through three plane of reflection in proper order, because the refracting index mismatch of plane of reflection, some incident light can reflect back. Therefore, the first reflecting surface (311) and the second reflecting surface (312) form an air cavity with the length L1 (321); the second reflective surface (312) and the third reflective surface (313) form a quartz cavity having a length L2 (322). The complex amplitude of the light reflected by the first reflecting surface (311) is E1, the complex amplitude of the light reflected by the second reflecting surface (312) is E2, and the complex amplitude of the light reflected by the third reflecting surface (313) is E3. The reflected light E1, E2 and E3 interfere and are received by the spectrometer (3) through the circulator (2), showing the interference spectrum of the sensor.
The broadband light source (1) in the embodiment is used for generating optical signals, the optical signals sent by the broadband light source (1) enter the sensing head (4) after passing through the circulator (2), sequentially pass through the air cavity and the quartz cavity, and light reflected by the three reflecting surfaces interferes and is received by the spectrometer (3) through the circulator (2). The interference spectrum displayed by the spectrometer (3) is an envelope spectrum generated due to vernier effect. Because the air holes exist in the suspended core optical fiber, the outside is the same as the air cavity, and therefore the outside air pressure is the same as the air pressure in the hollow optical fiber. When the external air pressure is changed, the air pressure in the air cavity changes along with the outside, so that the optical path difference in the air cavity can be changed, the reflection envelope spectrum is subjected to frequency shift, and the outside air pressure can be detected.
In the second embodiment, the manufacturing method of the sensor head of the present invention is described with reference to fig. 2, and this embodiment is a further limitation of the fiber pressure sensor based on the dislocation fusion and vernier effect described in the first embodiment, in which the inner diameter of the hollow core fiber (32) is 75 μm, the outer diameter is 125 μm, and the length is 200 μm; the single mode fiber has an outer diameter of 125 μm, a fiber core diameter of 9 μm, and a fiber length of 50 cm. The FP cavity formed by the first reflecting surface (311) and the second reflecting surface (312) is called an air cavity, and the free spectral range of the cavity is 6.01 nm. The outer diameter of the suspended core optical fiber (33) is 125 mu m, the inner diameter is 25 mu m, the core diameter is 9 mu m, the length is 147.7 mu m, an FP cavity formed by the second reflecting surface (312) and the third reflecting surface (313) is called a quartz cavity, the free spectral range of the cavity is 5.61nm, the suspended core optical fiber (33) and the hollow core optical fiber (32) need to be subjected to dislocation welding, and the dislocation distance is 8 mu m. The manufacturing process of the invention is carried out under the condition of constant temperature.
The embodiment defines the hollow-core optical fiber (32) with an inner diameter of 75 μm, an outer diameter of 125 μm and a length of 200 μm; the FP cavity formed by the first reflecting surface (311) and the second reflecting surface (312) is called an air cavity, and the free spectral range of the cavity is 6.01 nm. The outer diameter of the suspended core optical fiber (33) is 125 mu m, the inner diameter is 25 mu m, the core diameter is 9 mu m, the length is 147.7 mu m, an FP cavity formed by the second reflecting surface (312) and the third reflecting surface (313) is called a quartz cavity, the free spectral range of the cavity is 5.61nm, the suspended core optical fiber (33) and the hollow core optical fiber (32) need to be subjected to dislocation welding, and the dislocation distance is 8 mu m. The single mode fiber has an outer diameter of 125 μm, a fiber core diameter of 9 μm, and a fiber length of 50 cm. The specific manufacturing steps of the sensing head are as follows:
welding the single-mode fiber with the hollow fiber:
and (3) welding one end of the single-mode optical fiber with the smooth section with one end of the hollow optical fiber by using a precise optical fiber welding machine. The outer diameters of the single-mode optical fibers and the hollow-core optical fibers are the same and are 125 micrometers, and the hollow-core optical fibers with different lengths and different inner diameters are selected according to actual measurement requirements. In this example, the length of the hollow core fiber is 200 μm, the inner diameter of the hollow core fiber is 75 μm, the length of the single mode fiber is 50cm, and the core diameter of the single mode fiber is 9 μm.
Welding the hollow optical fiber and the suspension core optical fiber:
and welding the other end of the hollow optical fiber with the suspended core optical fiber by using a precise optical fiber welding machine. The outer diameters of the hollow optical fiber and the suspension core optical fiber are the same, the hollow optical fiber and the suspension core optical fiber are required to be subjected to dislocation welding to ensure the vernier effect, the dislocation distance is 8 micrometers, the outer diameter of the suspension core optical fiber is 125 micrometers, the inner diameter is 25 micrometers, the diameter of the fiber core is 9 micrometers, the length of the fiber core is 147.7 micrometers, and the free spectrum range is 5.61 nm.
Firstly, fixing the hollow optical fiber on a glass slide by using UV glue, and in order to ensure the welding effect, completing the manufacturing process under a high-power microscope, firstly welding the single-mode optical fiber and one end of the hollow optical fiber. Secondly, the other end of the hollow-core optical fiber is welded with the suspended-core optical fiber in a dislocation welding mode, and the dislocation quantity is 8 mu m. And finally, cutting the suspended core optical fiber according to the manufacturing requirement.
The language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter. Accordingly, many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the appended claims.
Claims (4)
1. Optical fiber air pressure sensor based on dislocation butt fusion and vernier effect, its characterized in that, air pressure sensor includes broadband light source (1), circulator (2), spectrum appearance (3), sensing head (4), wherein:
the sensing head (4) is composed of a single-mode optical fiber (31), a hollow-core optical fiber (32) and a suspension core optical fiber (33); the hollow core optical fiber (32) and the single mode optical fiber (31) are welded to form a first reflecting surface (311), the other end of the hollow core optical fiber is welded to the suspension core optical fiber (33) to form a second reflecting surface (312), a third reflecting surface (313) is formed between the tail end of the suspension core optical fiber (33) and the air, in order to ensure that the light reflected by the suspension core optical fiber (33) is consistent with the light path in the single mode optical fiber (31), namely, an interference spectrum with high contrast is obtained, the suspension core optical fiber (33) and the hollow core optical fiber (32) need to be welded in a staggered mode, the fiber cores of the suspension core optical fiber and the hollow core optical fiber are kept at the same horizontal line, the other end of the suspension core optical fiber (33) is connected with the air;
optical signals sent by the broadband light source (1) enter the sensing head (4) after passing through the circulator (2), and optical signals reflected by the sensing head (4) enter the spectrometer (3) through the circulator (2).
2. The fiber optic air pressure sensor based on staggered welding and vernier effect as claimed in claim 1, wherein the hollow-core fiber (32) has an inner diameter of 75 μm, an outer diameter of 125 μm and a length of 200 μm, and the FP cavity formed by the first reflecting surface (311) and the second reflecting surface (312) is called an air cavity, and the free spectral range of the cavity is 6.01 nm.
3. The optical fiber air pressure sensor based on staggered welding and vernier effect according to claim 1, wherein the outer diameter of the suspended core optical fiber (33) is 125 μm, the inner diameter is 25 μm, the core diameter is 9 μm, the length is 147.7 μm, the FP cavity formed by the second reflecting surface (312) and the third reflecting surface (313) is called a quartz cavity, the free spectral range of the cavity is 5.61nm, the suspended core optical fiber (33) and the hollow optical fiber (32) need to be staggered and welded, and the staggered distance is 8 μm.
4. The fiber optic air pressure sensor based on dislocation fusion and vernier effect as claimed in claim 1, wherein the single mode fiber has an outer diameter of 125 μm, a fiber core diameter of 9 μm and a fiber length of 50 cm.
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| CN112432724A (en) * | 2020-12-01 | 2021-03-02 | 东北林业大学 | Stress sensor based on vernier effect of optical fiber resonant cavity and stress measurement method |
| CN112629744A (en) * | 2020-12-03 | 2021-04-09 | 国网黑龙江省电力有限公司电力科学研究院 | Atmospheric pressure sensor based on cascade fiber Fabry-Perot interferometer |
| CN112629743A (en) * | 2020-12-03 | 2021-04-09 | 国网黑龙江省电力有限公司电力科学研究院 | Air pressure sensor based on optical fiber double-cavity vernier effect sensitization |
| CN112924082A (en) * | 2021-01-25 | 2021-06-08 | 广东海洋大学 | High-sensitivity air pressure sensor based on suspension core optical fiber and side hole optical fiber |
| CN112945284A (en) * | 2021-01-26 | 2021-06-11 | 广东海洋大学 | High-sensitivity high-temperature sensor based on suspension optical fiber dislocation welding |
| CN113218532A (en) * | 2021-06-29 | 2021-08-06 | 哈尔滨理工大学 | Temperature sensor based on sensitization of optical fiber double-cavity double-vernier effect |
| CN113533255A (en) * | 2021-07-27 | 2021-10-22 | 广东海洋大学 | Refractive index sensor and system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112432724A (en) * | 2020-12-01 | 2021-03-02 | 东北林业大学 | Stress sensor based on vernier effect of optical fiber resonant cavity and stress measurement method |
| CN112629744A (en) * | 2020-12-03 | 2021-04-09 | 国网黑龙江省电力有限公司电力科学研究院 | Atmospheric pressure sensor based on cascade fiber Fabry-Perot interferometer |
| CN112629743A (en) * | 2020-12-03 | 2021-04-09 | 国网黑龙江省电力有限公司电力科学研究院 | Air pressure sensor based on optical fiber double-cavity vernier effect sensitization |
| CN112924082A (en) * | 2021-01-25 | 2021-06-08 | 广东海洋大学 | High-sensitivity air pressure sensor based on suspension core optical fiber and side hole optical fiber |
| WO2022156298A1 (en) * | 2021-01-25 | 2022-07-28 | 广东海洋大学 | High-sensitivity air pressure sensor based on suspended-core optical fiber and side-hole optical fiber |
| CN112924082B (en) * | 2021-01-25 | 2021-09-28 | 广东海洋大学 | High-sensitivity air pressure sensor based on suspension core optical fiber and side hole optical fiber |
| CN112945284B (en) * | 2021-01-26 | 2021-09-21 | 广东海洋大学 | High-sensitivity high-temperature sensor based on suspension optical fiber dislocation welding |
| CN112945284A (en) * | 2021-01-26 | 2021-06-11 | 广东海洋大学 | High-sensitivity high-temperature sensor based on suspension optical fiber dislocation welding |
| WO2022160822A1 (en) * | 2021-01-26 | 2022-08-04 | 广东海洋大学 | High-sensitivity high-temperature sensor based on suspended optical fiber dislocation fusion splicing |
| CN113218532A (en) * | 2021-06-29 | 2021-08-06 | 哈尔滨理工大学 | Temperature sensor based on sensitization of optical fiber double-cavity double-vernier effect |
| CN113533255A (en) * | 2021-07-27 | 2021-10-22 | 广东海洋大学 | Refractive index sensor and system |
| CN113533255B (en) * | 2021-07-27 | 2022-06-14 | 广东海洋大学 | Refractive index sensor and system |
| CN113945542A (en) * | 2021-09-10 | 2022-01-18 | 汕头大学 | Optical fiber sensor, detection device based on optical fiber sensor and application of detection device |
| CN113945542B (en) * | 2021-09-10 | 2023-11-14 | 汕头大学 | Optical fiber sensor, detection device based on optical fiber sensor and application of detection device |
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