Study On Fabrication And Application Of Fiber Braen Grating Devices

Fiber Bragg grating (FBG) is an important passive optical componentwhich plays a critical role in optical communication networks and fiber sensingfields. This dissertation introduces the basic theory of FBG and makes a detailedsummary of fabrication techniques of FBG. Then, following research projects werecarried out.1. A double-frequency argon ion laser based FBG fabrication system and a CO2laser based long-period fiber grating (LPFG) fabrication system were set up. Thefrequency-doubled argon ion laser based system takes use of the beam scanning andphase-mask method. An electrical translation stage, an optical shutter and apiezoceramics were integrated into this system. Utility software was developed onthe Labview platform. Various fiber gratings, including uniform fiber Bragg grating,phase-shifted fiber Bragg grating, sampled fiber Bragg grating, tilted fiber Bragggrating and LPFG were fabricated successfully.2. A novel fiber Bragg grating device, superimposed fiber grating device bysuperimposing a uniform FBG onto a tilted fiber Bragg grating (TFBG) wasproposed and fabricated. It was successfully fabricated in a high-germanium-dopedfiber with the frequency-doubled argon ion laser system. Part of the incident light isreflected by the FBG and modulated by the TFBG twice. Intensity-modulatedsensing schemes of several parameters can be realized by using the sensingcharacteristics of the special grating structure.3. A fiber bending sensor based on the superimposed fiber grating device wasproposed and demonstrated. Bragg resonance of the TFBG doesn’t change whenbending states varies, so it can be used as power reference to eliminate the influenceof the instability of optical source. The reflected power of the TFBG was normalizedand the sensitivity of the device was0.6dB/m-1in the curvature range of33m-1~45m-1.4. A cantilever beam based phased-shifted chirped fiber Bragg grating (PS-CFBG) fiber filter was proposed. The filtering characteristics of the PS-CFBGwere simulated by using Matlab software. By incorporating a triangle cantileverbeam, chirp rate of the PS-CFBG can be tuned continuously. As a result,transmission spectra wavelength intervals can be changed continuously.