The Fabrication Of Fiber Grating And Application Of Fiber Refractometers

Recently,optical fiber sensors have aroused a lot of attentions.Compared with conventional electrical sensors,optical fiber sensors possess a large number of advantages such as electrically passive,immunity to electromagnetic interference,high temperature and anti-corrosion resistance,lossless joint with optical communicative network,distributed and long-distanced measurement and ease to multiplex.Therefore,they are widely used in conventional measurements for temperature,strain and refractive index,but also in novel measurements for relative humidity,magnetic field and so on.This dissertation introduces the basic theory,the fabrication techniques and the industry applications of FBG.Then,following research projects were carried out.1?A deep UV argon ion laser based semi-automatic FBG fabrication system by using phase-mask method was set up.Various fiber gratings,including uniform fiber Bragg grating,apodized fiber Bragg grating,phase-shifted fiber Bragg grating,tilted fiber Bragg grating,Long period fiber grating and Sampled fiber Bragg grating were fabricated successfully.2?we propose and experimentally demonstrate a refractive index measurement technique by using the combination of a TFBG and a waist-enlarged fusion bitaper(WEFBT).The both devices can couple light between core and cladding modes with coupling coefficients depending on ambient refractive index.The combination changes the operation mode from transmission into reflection and the measurement is intensity-modulated.What's more,by using different sensing segment we successfully achieved refractive index measurement of two ranges respectively from1.33 to 1.43 and from 1.38 to 1.45.This adds to the flexibility when the refractive index sensor is used in various applications.