阅读说明：本技术 一种强倏逝场干涉仪级联光反射器件的高灵敏温度传感器 (High-sensitivity temperature sensor of cascade light reflection device of interferometer with strong evanescent field ) 是由 郭东来 程曙 胡文彬 程乘 杨明红 于 2020-12-14 设计创作，主要内容包括：一种强倏逝场干涉仪级联光反射器件的高灵敏温度传感器,其包括外包裹层、干涉仪与光反射器件,所述干涉仪包括包层及其内设置的多根纤芯,所述干涉仪的一端与光源相连接,干涉仪的另一端与光反射器件相串联,包层的中部外包裹有外包裹层,该外包裹层为热光材料,外包裹层的外部包裹有毛细金属管,所述热光材料为聚二甲基硅氧烷、聚酰亚胺、氟化镁或聚氨酯。本设计不仅能监测环境的温度,灵敏度较高,而且便于解调,能实时在线监测。(A high-sensitivity temperature sensor of a cascade light reflection device of a strong evanescent field interferometer comprises an outer wrapping layer, an interferometer and a light reflection device, wherein the interferometer comprises a wrapping layer and a plurality of fiber cores arranged in the wrapping layer, one end of the interferometer is connected with a light source, the other end of the interferometer is connected with the light reflection device in series, the outer wrapping layer is wrapped outside the middle of the wrapping layer and is made of a thermo-optic material, a capillary metal tube is wrapped outside the outer wrapping layer, and the thermo-optic material is polydimethylsiloxane, polyimide, magnesium fluoride or polyurethane. The design can not only monitor the temperature of the environment, has higher sensitivity, but also is convenient for demodulation and can monitor on line in real time.)

1. A high-sensitivity temperature sensor of a cascade light reflection device of a strong evanescent field interferometer is characterized in that: the high-sensitivity temperature sensor comprises an outer wrapping layer (1), an interferometer (2) and a light reflecting device (3), wherein the interferometer (2) comprises a wrapping layer (21) and a plurality of fiber cores (22) arranged in the wrapping layer;

one end of the interferometer (2) is connected with the light source (5), the other end of the interferometer (2) is connected with the light reflection device (3) in series, an outer wrapping layer (1) is wrapped outside the middle of the interferometer (2), and the outer wrapping layer (1) is made of thermo-optic materials.

2. The high-sensitivity temperature sensor of the strong evanescent field interferometer cascade optical reflection device as claimed in claim 1, wherein: the absolute value of the thermo-optic coefficient of the thermo-optic material is more than 3 x 10⁴The refractive index is 1.38-1.43, and the surface tension is 20.6-21.2 mN/m.

3. The high-sensitivity temperature sensor of the strong evanescent field interferometer cascade optical reflection device as claimed in claim 2, wherein: the thermo-optic material is polydimethylsiloxane, polyimide, magnesium fluoride or polyurethane.

4. A highly sensitive temperature sensor of a strong evanescent field interferometer cascade optical reflection device as claimed in claim 1, 2 or 3, wherein: the wave band selection width of the light reflection device (3) is 1.1-1.6 times of the free spectrum width of a sensing peak of the interferometer (2).

5. The high-sensitivity temperature sensor of the strong evanescent field interferometer cascade optical reflection device as claimed in claim 4, wherein: the central wavelength range of the wave band of the light reflection device (3) is 1.2-2.0 times of the wavelength range of the sensing peak of the interferometer (2).

6. A highly sensitive temperature sensor of a strong evanescent field interferometer cascade optical reflection device as claimed in claim 1, 2 or 3, wherein: the light reflection device (3) is a fiber Bragg grating, a broadband Bragg grating or a nano silver reflection film with a modified surface.

7. A highly sensitive temperature sensor of a strong evanescent field interferometer cascade optical reflection device as claimed in claim 1, 2 or 3, wherein: the interferometer (2) comprises a left optical fiber section (23), a left conical section (24), a straight waist section (25), a right conical section (26) and a right optical fiber section (27), one end of the left optical fiber section (23) is connected with the light source (5), and the other end of the left optical fiber section (23) sequentially passes through the left conical section (24), the straight waist section (25), the right conical section (26) and the right optical fiber section (27) and then is connected with the light reflection device (3) in series; the diameters of the left optical fiber section (23) and the right optical fiber section (27) are consistent, and the diameter of the straight waist section (25) is 1/10-1/20 of the diameter of the left optical fiber section (23);

the outer portions of the positions, close to the left conical section (24), on the left optical fiber section (23), the left conical section (24), the straight waist section (25), the right conical section (26) and the position, close to the right conical section (26), on the right optical fiber section (27) are wrapped with the same outer wrapping layer (1) together.

8. The highly sensitive temperature sensor of the strong evanescent field interferometer cascade optical reflection device as claimed in claim 7, wherein: the number of the fiber cores (22) is seven, the fiber cores comprise a middle core (221) and six peripheral cores (222), and all the peripheral cores (222) are uniformly distributed around the middle core (221) in a regular hexagon shape.

9. The highly sensitive temperature sensor of the strong evanescent field interferometer cascade optical reflection device as claimed in claim 8, wherein: the diameter of the fiber core (22) is 9 mu m, the distance between adjacent fiber cores (22) is 35 mu m, the diameters of the left fiber section (23) and the right fiber section (27) are both 125 mu m, and the diameter of the straight waist section (25) is 6 mu m-15 mu m.

10. A highly sensitive temperature sensor of a strong evanescent field interferometer cascade optical reflection device as claimed in claim 1, 2 or 3, wherein: the outer part of the outer wrapping layer (1) is wrapped with a capillary metal pipe (4).

Technical Field

The invention relates to an optical fiber temperature sensor, belongs to the technical field of optical fiber sensing, also belongs to the cross field of material science and photoelectronic technology, and particularly relates to a high-sensitivity temperature sensor of a cascade light reflection device of a strong evanescent field interferometer.

Background

The temperature is a physical quantity for representing the cold and hot degree of an object, and is one of basic detection parameters in industries such as industrial automation, household appliances, environmental protection, safety production, automobile industry and the like. Particularly, with the rapid development of current science and technology, people have higher and higher requirements on the environmental temperature measurement precision.

The resistance-type and the galvanic couple-type thermometers which are widely used at present are commonly used for various environment monitoring, and meanwhile, other technologies are used for monitoring the change of the environment temperature, including a transistor temperature sensor, a microwave temperature sensor, a capacitance temperature sensor and the like, but the above technologies have the following defects more or less: the electromagnetic interference resistance is weak, the volume is large, the price is high, and the like, and the defects will influence the monitoring accuracy and sensitivity.

The information disclosed in this background section is only for enhancement of understanding of the general background of the patent application and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Disclosure of Invention

The invention aims to overcome the defects and problems of low sensitivity in the prior art and provide a high-sensitivity temperature sensor of a strong evanescent field interferometer cascade light reflection device with high sensitivity.

In order to achieve the above purpose, the technical solution of the invention is as follows: a high-sensitivity temperature sensor of a cascade light reflection device of a strong evanescent field interferometer comprises an outer wrapping layer, an interferometer and a light reflection device, wherein the interferometer comprises a wrapping layer and a plurality of fiber cores arranged in the wrapping layer;

one end of the interferometer is connected with the light source, the other end of the interferometer is connected with the light reflection device in series, an outer wrapping layer is wrapped outside the middle of the interferometer, and the outer wrapping layer is made of a thermo-optic material.

The absolute value of the thermo-optic coefficient of the thermo-optic material is more than 3 x 10⁴The refractive index is 1.38-1.43, and the surface tension is 20.6-21.2 mN/m.

The thermo-optic material is polydimethylsiloxane, polyimide, magnesium fluoride or polyurethane.

The wave band selection width of the light reflection device is 1.1-1.6 times of the free spectrum width of a sensing peak of the interferometer.

The central wavelength range of the wave band of the light reflection device is 1.2-2.0 times of the wavelength range of the sensing peak of the interferometer.

The light reflection device is a fiber Bragg grating, a broadband Bragg grating or a nano silver reflection film with a modified surface.

The interferometer comprises a left optical fiber section, a left conical section, a straight waist section, a right conical section and a right optical fiber section, wherein one end of the left optical fiber section is connected with a light source, and the other end of the left optical fiber section is connected with a light reflecting device in series after passing through the left conical section, the straight waist section, the right conical section and the right optical fiber section in sequence; the diameters of the left optical fiber section and the right optical fiber section are consistent, and the diameter of the straight waist section is 1/10-1/20 of the diameter of the left optical fiber section;

the outer parts of the part close to the left conical section on the left optical fiber section, the left conical section, the straight waist section, the right conical section and the part close to the right conical section on the right optical fiber section are wrapped with the same outer wrapping layer.

The number of the fiber cores is seven, the fiber cores comprise a middle core and six peripheral cores, and all the peripheral cores are uniformly distributed around the middle core in a regular hexagon.

The diameter of the fiber core is 9 mu m, the distance between adjacent fiber cores is 35 mu m, the diameters of the left fiber section and the right fiber section are both 125 mu m, and the diameter of the straight waist section is 6 mu m-15 mu m.

The outside of the outer wrapping layer is wrapped with a capillary metal pipe.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention relates to a high-sensitivity temperature sensor of a cascade light reflection device of a strong evanescent field interferometer, which comprises an outer wrapping layer, an interferometer and a light reflection device, wherein the interferometer comprises a wrapping layer and a plurality of fiber cores arranged in the wrapping layer, one end of the interferometer is connected with a light source, the other end of the interferometer is connected with the light reflection device in series, the outer wrapping layer (namely a thermo-optical material) is wrapped outside the middle part of the interferometer, when the high-sensitivity temperature sensor is used, incident light emitted by the light source passes through the interferometer to generate an interference spectrum, and after the interference spectrum passes through the light reflection device, a sensing peak in the interference spectrum can be reflected back to the interferometer, and the high-sensitivity temperature sensor has the following advantages:

firstly, the temperature change of the external environment can cause the refractive index of the thermo-optic material to generate corresponding linear change, and the refractive index change of the thermo-optic material can cause the wavelength of an interference spectrum generated by an interferometer to drift, so that a linear relation is established between the external environment temperature and the wavelength of the interference spectrum, the defect of low temperature sensitivity of the interferometer is overcome, and the sensitization is realized; secondly, when the interference spectrum is generated for the first time, the sensitization of the thermo-optic material can be obtained, and after a sensing peak in the interference spectrum is reflected back to the interferometer, the sensitization of the thermo-optic material can be obtained again, so that the intensity of the sensing peak can be greatly increased, and the sensitivity can be greatly improved. Therefore, the invention can not only monitor the temperature of the environment, but also has higher sensitivity.

2. In the high-sensitivity temperature sensor of the cascade light reflection device of the strong evanescent field interferometer, when a sensing peak in an interference spectrum is reflected back to the interferometer, the intensity of the sensing peak is greatly increased due to the sensitization of a thermo-optic material, so that the subsequent demodulation of the sensing peak is facilitated, and the real-time online monitoring is facilitated. Therefore, the invention is convenient for demodulation and can carry out real-time online monitoring.

3. In the high-sensitivity temperature sensor of the cascade light reflection device of the strong evanescent field interferometer, the capillary metal tube is wrapped outside the outer wrapping layer, and when the high-sensitivity temperature sensor is applied, the capillary metal tube can protect and package the outer wrapping layer (namely, a thermo-optic material), so that the defect of flexibility of the thermo-optic material is overcome, the response time can be shortened, the interference of vibration or pressure on the sensing is avoided, and the high-sensitivity temperature sensor is favorable for realizing online real-time high-precision demodulation. Therefore, the invention is convenient for packaging and fixing, has stronger anti-interference capability and is beneficial to realizing high-precision monitoring.

Drawings

Fig. 1 is a schematic structural view of the present invention.

Fig. 2 is a transverse cross-sectional view of fig. 1.

FIG. 3 is a schematic diagram of the interferometer of FIG. 1.

Fig. 4 is a transverse cross-sectional view of fig. 3.

Fig. 5 is a schematic diagram of the application of the present invention.

FIG. 6 is a comparative temperature sensitivity diagram of example 1 of the present invention.

In the figure: the fiber-optic interferometer comprises an outer wrapping layer 1, an interferometer 2, a cladding 21, a fiber core 22, a middle core 221, a peripheral core 222, a left optical fiber section 23, a left conical section 24, a straight waist section 25, a right conical section 26, a right optical fiber section 27, a light reflecting device 3, a capillary metal tube 4, a light source 5, an end-sealing sleeve head 6, a thermo-optic material pouring window 7 and a demodulator 8.

Detailed Description

The present invention will be described in further detail with reference to the following description and embodiments in conjunction with the accompanying drawings.

Referring to fig. 1-5, a high-sensitivity temperature sensor of a cascade light reflection device of a strong evanescent field interferometer comprises an outer wrapping layer 1, an interferometer 2 and a light reflection device 3, wherein the interferometer 2 comprises a wrapping layer 21 and a plurality of fiber cores 22 arranged in the wrapping layer;

one end of the interferometer 2 is connected with the light source 5, the other end of the interferometer 2 is connected with the light reflection device 3 in series, the outer wrapping layer 1 wraps the middle part of the wrapping layer 21, and the outer wrapping layer 1 is made of thermo-optic materials.

The absolute value of the thermo-optic coefficient of the thermo-optic material is more than 3 x 10⁴The refractive index is 1.38-1.43, and the surface tension is 20.6-21.2 mN/m.

The thermo-optic material is polydimethylsiloxane, polyimide, magnesium fluoride or polyurethane.

The wave band selection width of the light reflection device 3 is 1.1-1.6 times of the free spectrum width of the sensing peak of the interferometer 2.

The central wavelength range of the wave band of the light reflection device 3 is 1.2-2.0 times of the wavelength range of the sensing peak of the interferometer 2.

The light reflection device 3 is a fiber Bragg grating, a broadband Bragg grating or a nano silver reflection film with a modified surface.

The interferometer 2 comprises a left optical fiber section 23, a left conical section 24, a straight waist section 25, a right conical section 26 and a right optical fiber section 27, one end of the left optical fiber section 23 is connected with the light source 5, and the other end of the left optical fiber section 23 passes through the left conical section 24, the straight waist section 25, the right conical section 26 and the right optical fiber section 27 in sequence and then is connected with the light reflection device 3 in series; the diameters of the left optical fiber section 23 and the right optical fiber section 27 are consistent, and the diameter of the straight waist section 25 is 1/10-1/20 of the diameter of the left optical fiber section 23;

the same outer wrapping layer 1 is wrapped outside the part, close to the left conical section 24, on the left optical fiber section 23, the left conical section 24, the straight waist section 25, the right conical section 26 and the part, close to the right conical section 26, on the right optical fiber section 27.

The number of the fiber cores 22 is seven, and the fiber cores include a middle core 221 and six peripheral cores 222, and all the peripheral cores 222 are uniformly distributed around the middle core 221 in a regular hexagon.

The diameter of the fiber core 22 is 9 μm, the distance between adjacent fiber cores 22 is 35 μm, the diameters of the left fiber section 23 and the right fiber section 27 are 125 μm, and the diameter of the straight waist section 25 is 6 μm-15 μm.

The outside of the outer wrapping layer 1 is wrapped with a capillary metal pipe 4.

The principle of the invention is illustrated as follows:

in the invention, the optical fiber is heated, melted and tapered into a micro-nano size, so that an evanescent field (comprising a left tapered section 24, a straight waist section 25 and a right tapered section 26, especially a strong evanescent field is formed on the surface of the straight waist section 25) is formed on the surface of the optical fiber, thus obtaining an interferometer, then the interferometer is contacted with a thermo-optic material (namely an outer wrapping layer), and finally, a capillary metal tube is used for packaging.

When the interferometer is applied, interference spectrum is generated when light passes through the interferometer, and at the moment, the effective refractive index of the interferometer is changed due to the change of the external temperature or the refractive index, so that the wavelength drift of the interference spectrum is caused, and the change of the external temperature or the refractive index is induced. However, since the thermo-optic coefficient of silicon dioxide is small and the temperature sensitivity of the interferometer is low, the design mainly focuses on the change of the external refractive index, and therefore, the thermo-optic material is wrapped outside the interferometer, namely, the relation between the change of the refractive index of the thermo-optic material and the wavelength drift is focused, and the linear change of the refractive index of the thermo-optic material is caused by the change of the external environmental temperature of the thermo-optic material, so that a linear corresponding relation is established between the external environmental temperature and the wavelength drift.

The refractive index of the thermo-optic material is 1.3907-1.4125 and the temperature is 10-60 ℃.

The light reflection device in the invention is a waveband selective light reflection device.

Example 1:

referring to fig. 1-5, a high-sensitivity temperature sensor of a strong evanescent field interferometer cascade light reflection device comprises an outer wrapping layer 1, an interferometer 2, a light reflection device 3 and a capillary metal tube 4, wherein the interferometer 2 comprises a wrapping layer 21 and seven fiber cores 22 (including a middle core 221 and six peripheral cores 222, all the peripheral cores 222 are uniformly distributed around the middle core 221 in a regular hexagon) arranged in the wrapping layer, the interferometer 2 comprises a left optical fiber section 23, a left tapered section 24, a straight waist section 25, a right tapered section 26 and a right optical fiber section 27, one end of the left optical fiber section 23 is connected with a light source 5, and the other end of the left optical fiber section 23 is connected with the light reflection device 3 in series after passing through the left tapered section 24, the straight waist section 25, the right tapered section 26 and the right optical fiber section 27 in sequence; the diameters of the left optical fiber section 23 and the right optical fiber section 27 are consistent, and the diameter of the straight waist section 25 is 1/10-1/20 of the diameter of the left optical fiber section 23; the outer parts of the positions, close to the left conical section 24, on the left optical fiber section 23, the left conical section 24, the straight waist section 25, the right conical section 26 and the position, close to the right conical section 26, on the right optical fiber section 27 are wrapped with the same outer wrapping layer 1, and the outer wrapping layer 1 is made of a thermo-optic material (polydimethylsiloxane in the embodiment).

According to experimental data, the sensitivity of the high-sensitivity temperature sensor can reach 14338 pm/DEG C, compared with a bare fiber MZI, the sensitivity is increased by 500 times, and the precision can reach 0.001 ℃ at most.

In addition, please refer to fig. 6, which is a schematic diagram illustrating temperature sensitivity comparison of this embodiment 1, it can be seen that the sensitivity of the sensor to temperature is greatly increased after the polydimethylsiloxane is wrapped.

Example 2:

the basic contents are the same as example 1, except that:

the thermo-optical material is magnesium fluoride, and the interferometer is a tapered seven-core optical fiber Mach-Zehnder interferometer.

Example 3:

the basic contents are the same as example 1, except that:

the thermo-optical material is polyurethane, and the interferometer is a tapered single-mode core optical fiber Mach-Zehnder interferometer.

The above description is only a preferred embodiment of the present invention, and the scope of the present invention is not limited to the above embodiment, but equivalent modifications or changes made by those skilled in the art according to the present disclosure should be included in the scope of the present invention as set forth in the appended claims.