Research On Liquid Detection Sensor Based On Coated Reflection Tapered Fiber

With the development of science and technology,optical fiber sensing technology has gradually penetrated into many fields,such as industry,medicine and environmental protection,etc.Various types of optical fiber sensors have also been researched and put into practical application.In order to realize the reusable and high-sensitivity of taper fiber liquid detection sensor,this paper proposed and prepared three types of SMF(single-mode fiber),such as melt taper,end-face coating and U-Structure Tapered taper fiber,including coated taper fiber,linear taper fiber string structure sensor and U-shaped taper fiber cone probe.The main work and research results are as follows:1.The optical transmission path of the evanescent fiber in the taper fiber was analyzed in detail by the method of geometrical optics.In addition,the sensitivity relation of taper fiber sensor under strong conducting environment is deduced.The sensitivity of the sensor was numerically simulated with MATLAB software.The simulation results show that the sensitivity of taper fiber sensor can be improved by increasing the sensing length of fiber,the radius of fiber core and the working wavelength of fiber.2.The fabrication of tapered optical fiber was realized by using melt taper method.A new design of package structure of tapered optical fiber sensor was proposed.The movable device is creatively selected so that the maximum protection of the sensor from damage,to achieve taper fiber sensor reuse.3.Proposed in the taper fiber sensor end face coating,that is,the introduction of reflective components.The traditional transmission of light transmission path is changed to a reflective transmission,so that the light in the tapered fiber optic sensor forward transmission through the reflective element again through the sensing area.Doubling the sensor sensing length to increase the sensitivity of tapered optical fiber.4.According to the package structure of the taper fiber sensor,the hardware platform of the refractive index sensing system of the coated taper fiber is designed and built,and the refractive index characteristics of the taper fiber sensor is studied.The experimental data show that the sensitivity of the coated taper fiber sensor is/4711 RIUnm.5.A compact bent tapered optical fibre sensor is proposed and its concentrationsensing characteristics are explored.The structure of micro fibre Mach–Zehnder interferometer is fabricated using a glass processing system.A combination of bending and tapering acts as a sensor,which results in high penetration depth of evanescent field.The experimental data show that the U-shaped structure of Mach–Zehnder interferometer sensor sensitivity is about 1.49 fold greater than that of a straight structure sensor.In addition.