Research On Sensitization Technology Of Fiber-optic Microstructure Temperature Sensor

In the field of fiber-optic sensing,temperature has always been a physical parameter closely related to human production and life.In this paper,based on the research of optical fiber temperature sensing technology,three different high-sensitivity temperature sensors based on polymer-filled silica capillary tube(SCT)are proposed and manufactured.The developed F-P cavity fiber-optic microstructure sensor not only has high sensitivity,but also has an extremely simple preparation method,extremely easy to repeat,and extremely low cost.These advantages will make these sensors have greater application prospects in the field of temperature sensing.The main research work of this paper is as follows:(1)The physical properties of various liquid temperature-sensitive materials are analyzed,the filling method of liquid temperature-sensitive materials is summarized,the various factors affecting the filling process are deeply analyzed,and the corresponding theoretical model is established.This will provide the necessary basis and reference for the research of temperature sensitization technology.(2)Starting from multi-beam interference,theoretically,the mechanism of single F-P cavity and double F-P cavity to temperature response is deeply analyzed.(3)A polymer-filled single F-P cavity fiber-optic temperature sensor is proposed,and the preparation method of the sensing structure is introduced in detail.The geometric length and interface deformation of the F-P cavity are discussed.In the range of 40-50 ?,the highest temperature sensitivity reaches 1.45 nm/?,and the fitting degree of its linear fitting curve is99.98%.In addition,in order to eliminate the influence of pressure on the sensing structure,we packaged the sensing structure.(4)A polymer-filled single F-P air cavity fiber-optic temperature sensor is proposed,and the preparation method of the sensing structure is introduced in detail.The geometric length and interface deformation of the F-P cavity are further discussed and verified.In the range of35-54 °C,the temperature sensitivity of the sensing structure is up to-2.73 nm/°C,and the fitting degree of the linear fitting curve is 99.99%.In a low-pressure environment of 0?1 MPa,the response of the sensor to pressure is very weak.Even if the pressure changes by 1 MPa,it is only equivalent to a temperature change of 0.17 °C.(5)A polymer-filled double F-P cavity fiber-optic temperature sensor is proposed.The two cascaded F-P cavities use polymer and air as media respectively.The interference spectrum of the sensing structure is composed of two spatial frequency spectra,which are derived from a polymer cavity and an air cavity respectively.By controlling the length of the polymer and air cavity,highly sensitive temperature sensing can be achieved.In the range of29-35 °C,the temperature sensitivity of the sensing structure is up to-6.76 nm/°C,and the degree of fit of the linear fitting curve is 99.99%.In addition,it was discovered for the first time that a closed air cavity has a certain inhibitory effect on the thermal expansion of the polymer.In addition,the proposed sensor structure can be used for differential measurement of temperature and pressure.Theoretically,the differential measurement errors of temperature and pressure in the range of 29-35 °C and 0-1.2 MPa are 0.0047 °C and 0.0025 MPa,respectively.