Optical fiber temperature sensor based on convex-concave spherical mirror pair

Abstract

The utility model discloses an optical fiber temperature sensor based on a convex-concave spherical mirror pair, which belongs to the technical field of optical fiber sensors and consists of a broadband light source SLED (1), an optical circulator (2), a sensing structure (3) and a spectrum analyzer (4). The sensing structure (3) comprises a first single-mode optical fiber (301) with a convex spherical mirror, a first coreless optical fiber (302), a hollow-core optical fiber (303), a second coreless optical fiber (304) and a second single-mode optical fiber (305) with a concave spherical mirror; according to the utility model, more light in the fiber core is excited into the cladding through the coreless optical fiber, so that the sensitivity of the device to temperature is improved; through single mode-spherical structure-hollow fiber-spherical structure-single mode, light of the single-mode fiber excites multiple modes and is coupled to a fiber core and a cladding of the hollow fiber, and the multiple modes are reflected and coupled through a second spherical structure, so that the interference effect is enhanced, and the temperature sensitivity of the sensor is improved. The sensor has the characteristics of small size, easiness in manufacturing, simple structure, high temperature sensitivity and the like.

Description

Technical Field

[0001] This utility model relates to an optical fiber temperature sensor, and more particularly to an optical fiber temperature sensor based on a pair of convex and concave spherical mirrors, belonging to the field of optical fiber sensor technology. Background Technology

[0002] Fiber optic sensors are widely used in aerospace, petrochemical, medical, and power transmission fields due to their advantages such as strong anti-interference capability, small size, long transmission distance, and secure transmission. Currently, common fiber optic sensor measurement parameters include temperature, refractive index, strain, humidity, pressure, acceleration, and vibration. Temperature is a particularly important parameter in many application areas and has been a research hotspot in recent years. To improve temperature sensitivity, researchers from various countries have proposed many novel fiber optic sensing structures. For example, temperature sensors based on a combination of FBG and Mach-Zehnder interferometers offer a relatively large measurement range but cannot meet the requirements for high sensitivity. Temperature sensors fabricated by filling microstructured optical fibers with liquid crystals offer a wide measurement range and long transmission distance, but the system structure and demodulation scheme are complex and expensive, resulting in relatively low accuracy. Summary of the Invention

[0003] In order to overcome the shortcomings of the prior art, the present invention aims to provide an optical fiber temperature sensor based on a pair of convex and concave spherical mirrors. This sensor has the characteristics of small size, easy manufacturing, simple structure, and high temperature sensitivity.

[0004] The technical solution adopted by this utility model to solve the technical problem is as follows:

[0005] A fiber optic temperature sensor based on a pair of convex and concave spherical mirrors is characterized by comprising a broadband light source SLED (1), an optical circulator (2), a sensing structure (3), and a spectrometer (4); wherein the sensing structure (3) comprises a first single-mode fiber (301) with a convex spherical mirror, a first coreless fiber (302), a hollow fiber (303), a second coreless fiber (304), and a second single-mode fiber (305) with a concave spherical mirror; the broadband light source SLED (1) is connected to port one (201) of the optical circulator (2), and port two (202) of the optical circulator (2) is connected to the sensing structure (3). The first single-mode fiber (301) with a convex spherical mirror is connected, and port three (203) of the optical circulator (2) is connected to the spectrometer (4); the first single-mode fiber (301) with a convex spherical mirror connects one end of the convex spherical mirror to one end of the first coreless fiber (302), the other end of the first coreless fiber (302) is fused to one end of the hollow fiber (303), the other end of the hollow fiber (303) is fused to one end of the second coreless fiber (304), and the second single-mode fiber (305) with a concave spherical mirror connects one end of the concave spherical mirror to the other end (304) of the second coreless fiber.

[0006] The beneficial effects of this utility model are:

[0007] 1. By using coreless optical fiber, more light from the fiber core is excited into the cladding, thereby improving the device's temperature sensitivity.

[0008] 2. By using a single-mode-spherical structure-hollow fiber-spherical structure-single-mode, the light from the single-mode fiber is excited into multiple modes and coupled into the core and cladding of the hollow fiber. These multiple modes are then reflected and coupled through a second spherical structure, which enhances the interference effect and improves the temperature sensitivity of the sensor. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the structure of an optical fiber temperature sensor based on a pair of convex and concave spherical mirrors according to this utility model. Figure 2 This is a schematic diagram of the sensing structure (3).

[0010] 1 is a broadband light source SLED; 2 is an optical circulator; 3 is a sensing structure; 4 is a spectrometer; 301 is a first single-mode fiber with a convex spherical mirror; 302 is a first coreless fiber; 303 is a hollow fiber; 304 is a second coreless fiber; 305 is a second single-mode fiber with a concave spherical mirror.

[0011] Specific implementation methods

[0012] The following is a detailed description of the structure and working principle of this utility model:

[0013] A fiber optic temperature sensor based on a pair of convex and concave spherical mirrors is characterized by comprising a broadband light source SLED (1), an optical circulator (2), a sensing structure (3), and a spectrometer (4); wherein the sensing structure (3) comprises a first single-mode fiber (301) with a convex spherical mirror, a first coreless fiber (302), a hollow fiber (303), a second coreless fiber (304), and a second single-mode fiber (305) with a concave spherical mirror; the broadband light source SLED (1) is connected to port one (201) of the optical circulator (2), and port two (202) of the optical circulator (2) is connected to the sensing structure (3). The first single-mode fiber (301) with a convex spherical mirror is connected, and port three (203) of the optical circulator (2) is connected to the spectrometer (4); the first single-mode fiber (301) with a convex spherical mirror connects one end of the convex spherical mirror to one end of the first coreless fiber (302), the other end of the first coreless fiber (302) is fused to one end of the hollow fiber (303), the other end of the hollow fiber (303) is fused to one end of the second coreless fiber (304), and the second single-mode fiber (305) with a concave spherical mirror connects one end of the concave spherical mirror to the other end (304) of the second coreless fiber.

[0014] The working principle of an optical fiber temperature sensor based on a pair of convex and concave spherical mirrors:

[0015] A fiber optic temperature sensor based on a pair of convex and concave spherical mirrors. Figure 1 After all the components are connected, the light output from the broadband light source SLED (1) enters the first single-mode fiber (301) with a convex spherical mirror and propagates in the fundamental mode. Then, the light from the first single-mode fiber (301) with a convex spherical mirror enters the first coreless fiber (302). Due to mode field mismatch and the beam splitting effect of the convex spherical mirror, part of the light is reflected by the convex spherical mirror, and the other part of the light excites higher-order modes to propagate in the first coreless fiber (302). The light propagates in the hollow fiber (303) in the form of higher-order modes and the fundamental mode. The light enters the second coreless fiber (304) from the hollow fiber (303). Due to mode field mismatch and the converging effect of the concave spherical mirror, interference light is generated by coupling in the second coreless fiber (304). The second single-mode fiber (305) with a concave spherical mirror reflects part of the light back and interferes with the light reflected by the first single-mode fiber (301) with a convex spherical mirror. Example

[0016] Figure 1This is a schematic diagram of the structure of an optical fiber temperature sensor based on a pair of convex and concave spherical mirrors according to this utility model. In the sensing structure (3), the first coreless optical fiber (302) and the second coreless optical fiber (304) are 1.5 cm long, the hollow optical fiber (303) is 100 μm long, the first single-mode optical fiber (301) with a convex spherical mirror is formed by discharging and splicing two single-mode optical fibers to control the fiber advance amount, and is 3 cm long with a radius of curvature of 15 μm. The second single-mode optical fiber (305) with a concave spherical mirror is written by a femtosecond laser, and is 3 cm long with a radius of curvature of 15 μm. The broadband light source SLED (1) has a spectral range of 600-1600 nm, and the spectrometer (4) (Yokogawa AQ6370c) ); Port 1 (201) of the optical circulator (2) is connected to the broadband light source SLED (1), Port 2 (202) of the optical circulator (2) is connected to the first single-mode fiber (301) with a convex spherical mirror of the sensing structure (3), and Port 3 (203) of the optical circulator (2) is connected to the spectrometer (4); wherein the first single-mode fiber (301) with a convex spherical mirror of the sensing structure (3) connects one end of the convex spherical mirror to one end of the first coreless fiber (302), the other end of the first coreless fiber (302) is fused with one end of the hollow fiber (303), the other end of the hollow fiber (303) is fused with one end of the second coreless fiber (304), and the second single-mode fiber (305) with a concave spherical mirror connects one end of the concave spherical mirror to the other end (304) of the second coreless fiber.

[0017] The light output from the broadband light source SLED (1) enters the first single-mode fiber (301) with a convex spherical mirror and propagates in the fundamental mode. Then, it enters the first coreless fiber (302) from the first single-mode fiber (301) with a convex spherical mirror. Due to mode field mismatch and the beam splitting effect of the convex spherical mirror, part of the light is reflected by the convex spherical mirror, and the other part of the light is excited to propagate in the first coreless fiber (302) in the form of higher-order mode. The light propagates in the hollow fiber (303) in the form of higher-order mode and fundamental mode. The light enters the second coreless fiber (304) from the hollow fiber (303). Due to mode field mismatch and the converging effect of the concave spherical mirror, interference light is generated by coupling in the second coreless fiber (304). The second single-mode fiber (305) with a concave spherical mirror reflects part of the light back and interferes with the light reflected by the first single-mode fiber (301) with a convex spherical mirror.

[0018] The above embodiments are only one of the preferred embodiments among all the solutions of this utility model. Other simple modifications to a fiber optic temperature sensor based on a pair of convex and concave spherical mirrors are all within the scope of protection of this utility model.

Claims

1. A fiber-optic temperature sensor based on a convex-concave pair of spherical mirrors, characterized in that The system includes a broadband light source SLED (1), an optical circulator (2), a sensing structure (3), and a spectrometer (4); wherein the sensing structure (3) includes a first single-mode fiber (301) with a convex spherical mirror, a first coreless fiber (302), a hollow fiber (303), a second coreless fiber (304), and a second single-mode fiber (305) with a concave spherical mirror; the broadband light source SLED (1) is connected to port one (201) of the optical circulator (2), and port two (202) of the optical circulator (2) is connected to the first single-mode fiber (305) with a convex spherical mirror of the sensing structure (3). The first single-mode fiber (301) is connected to the optical circulator (2), and the port 3 (203) of the optical circulator (2) is connected to the spectrometer (4); the first single-mode fiber (301) with a convex spherical mirror connects one end of the convex spherical mirror to one end of the first coreless fiber (302), the other end of the first coreless fiber (302) is fused to one end of the hollow fiber (303), the other end of the hollow fiber (303) is fused to one end of the second coreless fiber (304), and the second single-mode fiber (305) with a concave spherical mirror connects one end of the concave spherical mirror to the other end of the second coreless fiber (304).

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