Voltage Sensor Using Tilted Fiber Grating Interacting With Liquid Crystal

Due to the small size small size, light weight, low loss, high sensitive, corrosion resistance, electrical insulation and the advantages of resistance to electromagnetic interference, fiber Bragg grating sensors has developed rapidly in recent years, and gradually replace the traditional sensors in many fields, and make up for the traditional sensor faults and blank. As a member of the family of fiber grating, tilted fiber Bragg grating(TFBG) has an advantage in many sensing fields because of its unique structure and characteristics. TFBG cannot only couple the light from backward propagating core mode to forward propagating core mode as normal FBGs do, but also couple the forward propagating core mode to backward propagating cladding modes。This makes on the refractive index(RI) measurement the tilted fiber Bragg grating not only has the advantages of fiber Bragg grating but also the long period fiber grating. So it is a very good choice to using the tilted fiber Bragg grating to make the refractive index sensor.Liquid crystal has both the fluidity of liquid and crystal optical properties. Its unique electro-optical properties make the liquid crystal birefringence characteristics can be controlled by electric field, so as to realize control the liquid crystal refractive index.Based on the characteristic of the title fiber grating refractometer and electro-optical properties of the liquid crystal, we design and make a voltage sensor using the title fiber grating interacting with liquid crystal, and study the relevant characteristics of the voltage sensor.This thesis mainly content is as follows:(1)Introduced the advantages of fiber optical sensor,and the typical use of it inmany sensing fields and the development prospect. Introduced the optical fibervoltage sensor.(2)Summary of tilted fiber grating relative to the fiber Bragg gratings and longperiod fiber grating have special advantages. Introduced the tilted fiber Bragggrating used in the temperature, axial stress, bending, vibration and therefractive index sensor(3)Introduce the liquid crystal optical properties and orderly characteristics,andthe classification of liquid crystal. And mainly introduce based on thechemical and physical methods of liquid crystal molecular orientationtechnology.(4)The experiment measuring the refractive index of tilted fiber Bragg gratingsensing characteristics, theoretical analysis the tilted fiber Bragg gratingmeasuring principle is different under the conditions of low refractive index(1.33 < SRI < 1.45) and high refractive conditions(SRI >1.45).(5)Design a voltage sensor using the title fiber grating interacting with liquidcrystal, Elaborated the voltage sensor operating principle: due to theelectro-optic effect of liquid crystal, under the action of electric field, theliquid crystal molecules will change orientation. Voltage would be measuredbase on the title fiber grating refractometer measure the liquid crystalrefractive index. Elaborated the production methods of the voltage sensor, theexperiment test system and sensor characteristic analysis.