Study On The Simultaneous Measuerement Of Temperature And Humifity Based On Fiber Grating

In recent years,with the development of industrial or agricultural and the advances in technology,researchers pay more and more attention on the accurate monitoring of the environmental temperature and humidity.Especially in food storage,gas,coal and other fields,the measurement of humidity is often needed.However,the electronic sensors are unable to accurate measurement of the temperature and humidity of special environment.Because the fiber grating sensor has very good insulation,stability and sensitivity,it is especially suitable for special environment.This work studied on simultaneous measurement of temperature and humidity based on fiber grating.Following are the main contents:Firstly,this paper introduces some basic situation of fiber grating including fiber grating development,classification and application of the sensor.The current situation and the development of fiber temperature and humidity sensing technology are reviewed.So it provides ideas for sensor design.Secondly,Analysis of two methods for fiber grating are discussed in detail,including the coupling mode theory and transfer matrix method.The parameters of the fiber grating are discussed in detail,including the effect of the period and the length of the grating,and the refractive index sensing properties of the long period fiber grating are discussed.For design and fabrication of temperature and humidity sensors provide theoretical support.Thirdly,a novel fiber grating sensor for simultaneous temperature and humidity measurement is proposed based on LPFG spliced between a FBG.And the temperature and humidity sensor principle are analyzed in detail.By studying the factors influencing sensitivity of the sensor for humidity.So the sensor performance is optimized.The experiment is set up,the sensor for humidity sensitivity up to 94.34pm/%RH.Finally,an optical fiber relative temperature and humidity sensor is proposed.And the propagation characteristic of FBG-FP and the principle of sensor for temperature and humidity are analyzed in detail.Encapsulating the FBG-FP cavity and making sensor.The experiment is set up,the sensor for humidity and temperature sensitivity up to 0.0682dB/%RH and10.88pm/?.