Femtosecond Laser Fabrication Of Fiber Bragg Grating And Investigation Of Its Sensing Applications

Fiber Bragg gratings (FBG) are key components in the fields of fiber communication,fiber sensing and fiber laser. The traditional method of fabricating FBGs was based on theuse of excimer laser and a phase mask, however, the fabrication of FBGs in this thesis wascarried out by use of femtosecond laser. This thesis is laid out along the line of theoryanalysis, simulation and experiment; its content can be divided into the following fourparts.1. Introduction of relevant theories about FBGs, mainly about the coupled modetheory. There is also a brief analysis of ionization mechanism happened during theinteraction between the femtosecond laser and dielectrics.2. A brief introduction of the FBG fabrication system, including relevant equipments,their parameters as well as their setup. Then, there is a detailed introduction about theprocedures of adjusting the optical path.3. Fiber Bragg grating (FBG) was fabricated by using femtosecond laser pulses, andbased on which Tilted Fiber Bragg Grating (TFBG) was fabricated by using femtosencondlaser pulses.4. The fabricated TFBG can detect the orientation and magnitude of the bending atany directions based on the asymmetric change of refractive index in two dimensions. Theexperiment results agree well with the theoretical prediction.