Bragg Fiber Grating Writing Technology And Special Fiber Grating Sensor

In this thesis, we investigate the optical field distribution of eccentric core optical fiber(ECOF) with conformal mapping method. We also research the grating writing process insingle mode fiber (SMF) and ECOF. The bending characteristics of the single core grating andmulti-fiber grating are analyzed. The main works are summed up as follows:1. The expressions of mode field distributions in an ECOF are derived with conformalmapping method. The mode effective refractive indices are calculated and compared with theindices obtained with the finite element method (FEM). The conformal transformationmethod is sufficient accuracy and can largely decrease the computation time with that theoffset distance of the core from the center of the fiber is small.2. The Bragg fiber grating fabrication system by UV exposure through a phase mask isbuilt. The fiber Bragg gratings in photosensitive optical fiber, hydrogen-loaded SMF andhydrogen ECOF are fabricated. The bending characteristics of the ECOF grating are alsoanalyzed. The effects of the hydrogen loading on the grating and the bleaching of the gratingare investigated.3. The system for testing bending characteristics of the sensor multi-fiber grating isdesigned. The experimental results show that the proposed sensor with multi-fiber grating canestimate the bending direction and angle, measure the multi-dimensional bending degree, andobtain the sensing characteristic curve of the sensor.4. In order to increase the flexibility of the grating writing system, we design andassemble Talbot interferometer which can write different wavelengths in the fiber grating witha single phase mask. We experimentally find that the debugging work of Talbot interferometeris difficult. This part of work still needs further study.Above all, a series of work around the fiber grating writing and eccentric core fibergrating sensor are carried out. We actualize the whole process from grating writing to sensortesting through the work.