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CN-121977719-A - Enhanced vernier effect optical fiber temperature sensor, preparation method thereof and temperature sensing system

CN121977719ACN 121977719 ACN121977719 ACN 121977719ACN-121977719-A

Abstract

The invention belongs to the technical field of temperature detection, and particularly relates to an enhanced vernier effect optical fiber temperature sensor, a preparation method thereof and a temperature sensing system. The invention provides an enhanced vernier effect optical fiber temperature sensor which comprises a Fabry-Perot interferometer and a Liao interferometer, wherein the Fabry-Perot interferometer and the Liao interferometer are connected in parallel, the Fabry-Perot interferometer comprises a single-mode optical fiber and a hollow optical fiber fixedly connected with the single-mode optical fiber, polydimethylsiloxane is filled in a cavity of the hollow optical fiber, and the Liao interferometer comprises an optical fiber polarizer and a second polarization maintaining optical fiber fixedly connected with a first polarization maintaining optical fiber of the optical fiber polarizer. The enhanced vernier effect optical fiber temperature sensor provided by the invention has the advantages of simple preparation flow, capability of realizing mass production, higher utilization rate of bandwidth, higher sensitivity and capability of meeting the use scene of ultrahigh sensitivity. A fairly high sensitivity of temperature monitoring can also be achieved when the equipment conditions are poor. The use threshold of the cursor sensor is significantly reduced.

Inventors

  • FANG XIAOHUI
  • JIAN YONGCHANG
  • LU DUNKE

Assignees

  • 广州大学

Dates

Publication Date
20260505
Application Date
20260306

Claims (10)

  1. 1. The enhanced vernier effect optical fiber temperature sensor is characterized by comprising a Fabry-Perot interferometer and a Liao interferometer which are connected in parallel, wherein the Fabry-Perot interferometer comprises a single-mode optical fiber and a hollow optical fiber fixedly connected with the single-mode optical fiber, polydimethylsiloxane is filled in a cavity of the hollow optical fiber, the length of the hollow optical fiber is 100-600 mu m, the Liao interferometer comprises an optical fiber polarizer, the optical fiber polarizer is provided with a first polarization maintaining optical fiber, a second polarization maintaining optical fiber fixedly connected with the first polarization maintaining optical fiber of the optical fiber polarizer, and a fast axis or a slow axis of the first polarization maintaining optical fiber and the second polarization maintaining optical fiber are in rotary dislocation connection.
  2. 2. The enhanced vernier effect optical fiber temperature sensor of claim 1, wherein the hollow optical fiber has a length of 180 to 480 μm.
  3. 3. The enhanced vernier effect optical fiber temperature sensor of claim 2, wherein the hollow optical fiber has a length of 350 μm.
  4. 4. The enhanced vernier effect optical fiber temperature sensor of claim 1, wherein the single mode optical fiber is of a type G652D, and the hollow optical fiber has an outer diameter of 140 μm and an inner diameter of 100 μm.
  5. 5. The enhanced vernier effect optical fiber temperature sensor of claim 1, wherein the first polarization maintaining optical fiber and the second polarization maintaining optical fiber are connected in a rotating and dislocating manner in a fast axis or a slow axis at an angle of 30-60 °.
  6. 6. The enhanced-vernier-effect optical fiber temperature sensor of claim 5, wherein the first polarization maintaining optical fiber and the second polarization maintaining optical fiber are connected at an angle of 45 ° with respect to a fast axis or a slow axis of rotation.
  7. 7. The enhanced vernier effect optical fiber temperature sensor of claim 1, wherein the second polarization maintaining optical fiber has a length of 110cm.
  8. 8. The method for manufacturing the enhanced vernier effect optical fiber temperature sensor according to any one of claims 1 to 7, which is characterized by comprising the following steps: Welding a single-mode optical fiber and an initial hollow optical fiber, cutting the welded initial hollow optical fiber to obtain a hollow optical fiber, immersing a cavity of the hollow optical fiber in a polydimethylsiloxane solution for filling, and finally curing to obtain the Fabry-Perot interferometer; and performing fusion welding after rotating and misplacing the fast axis or the slow axis of the first polarization maintaining optical fiber and the initial second polarization maintaining optical fiber of the optical fiber polarizer, and then cutting the welded initial second polarization maintaining optical fiber to obtain the Liao interferometer.
  9. 9. The method for preparing the Fabry-Perot interferometer according to claim 8, wherein the welding conditions for preparing the Fabry-Perot interferometer comprise that the discharge intensity is 45-55 units, the discharge time is 350-400 ms, the ratio of the filling time to the length of the hollow optical fiber is (0.45-1.25) h (180-480) mu m; The welding conditions for preparing the Liao interferometer comprise 80-120 units of discharge intensity, 1200-160 ms of discharge time and 30-60 degrees of rotation dislocation.
  10. 10. The temperature sensing system is characterized by comprising a supercontinuum light source, an optical fiber coupler, an enhanced vernier effect optical fiber temperature sensor prepared by the enhanced vernier effect optical fiber temperature sensor according to any one of claims 1-7 or the enhanced vernier effect optical fiber temperature sensor prepared by the preparation method according to claim 8 or 9, and a spectrum analyzer, wherein the optical fiber coupler is provided with a first connection port, a second connection port, a third connection port and a fourth connection port, the first connection port is connected with the supercontinuum light source, the second connection port is connected with a single-mode optical fiber of the Fabry-Perot interferometer, the third connection port is connected with an optical fiber polarizer of the Liao interferometer, and the fourth connection port is connected with the spectrum analyzer.

Description

Enhanced vernier effect optical fiber temperature sensor, preparation method thereof and temperature sensing system Technical Field The invention belongs to the technical field of temperature detection, and particularly relates to an enhanced vernier effect optical fiber temperature sensor, a preparation method thereof and a temperature sensing system. Background The optical fiber sensor has been widely applied and popularized in various fields such as physics, chemistry, biomedicine, etc. by virtue of the outstanding advantages of small volume, light weight, high sensitivity, strong anti-electromagnetic interference capability, etc. The temperature monitoring is taken as an extremely important basic link in daily life, industrial production and scientific research activities, has extremely high requirements on monitoring precision, stability and environmental adaptability, and the optical fiber temperature sensor becomes a preferable scheme for temperature monitoring under complex scenes such as high temperature, strong electromagnetic interference and the like due to the unique advantages of the optical fiber temperature sensor. At present, the optical fiber temperature sensor in the prior art is mainly divided into two main types, namely a temperature sensor constructed based on an optical fiber grating and a temperature sensor constructed based on an optical fiber interferometer. The temperature sensor constructed based on the fiber bragg grating has the characteristics of compact structure, but has the inherent defects of low sensitivity, easiness in generating signal crosstalk, higher preparation cost and the like, and is difficult to meet the requirement of a high-precision temperature monitoring scene, while the temperature sensor constructed based on the fiber bragg interferometer can realize higher sensing sensitivity, is more flexible and convenient to construct, is more suitable for the application requirement of ultra-high-precision temperature monitoring, and becomes one of the main technical routes in the current fiber temperature sensing field. In order to further improve the sensing sensitivity of the temperature sensor based on the optical fiber interferometer, in recent years, vernier effect has been widely introduced into the design of the optical fiber interferometer. The core principle of this technique is to combine a pair of interferometers with similar but slightly different free spectral ranges (Free Spectrum Range, FSR), where the interferometer directly sensing the measured temperature parameter is called the Sensing Interferometer (SI) and the interferometer used to provide the reference baseline is called the Reference Interferometer (RI). When FSRs of the two interferometers are matched, the comb-shaped interference spectrum generated by superposition of the two interferometers presents an approximately cosine-shaped envelope, and the wavelength drift amount of the envelope spectrum is far greater than that of the interference spectrum of a single interferometer along with the change of the measured temperature, so that the sensing sensitivity is remarkably improved. However, the conventional optical fiber temperature sensor based on vernier effect still has a plurality of technical defects, and the large-scale application and popularization of the optical fiber temperature sensor are limited. In the related art, the side surface of the hollow fiber is usually etched and grooved through a femtosecond laser system to fill Polydimethylsiloxane (PDMS), so as to construct a Fabry-Perot interferometer (FPI) for temperature sensing. The preparation process not only needs high-precision femtosecond laser equipment, so that the preparation cost is high, but also has extremely limited optical path difference increasing effect caused by the thermal expansion effect of PDMS (polydimethylsiloxane) because of almost no expansion space in the axial direction of the optical fiber, and the temperature sensitivity of the PDMS is directly reduced, and more seriously, when the cavity length increasing effect caused by the thermal expansion is smaller than the refractive index reducing effect caused by the PDMS thermo-optical effect, the sensitivity coefficient of the sensor is changed from a positive value to a negative value, so that the linear measurement range of the sensor is directly limited, and the accuracy and the stability of temperature measurement are seriously influenced. Meanwhile, the PDMS filling operation and the whole preparation flow of the FPI are complex, the process difficulty is high, mass production is not facilitated, and the application cost of the sensor is further increased. Disclosure of Invention The invention aims to provide an enhanced vernier effect optical fiber temperature sensor and a preparation method thereof, and the enhanced vernier effect optical fiber temperature sensor provided by the invention has simple preparation flow and can realize batch production