From The Q-switched Erbium-doped Fiber Laser Based On Stimulated Brillouin Scattering

In recent years, the fiber laser in the laser field has gained increasing concern among people. With the advancement and application of all-fiber optical devices, the research of the all-fiber laser has made a breakthrough. All-fiber laser whose full width at half maximum is narrow has always been a hot issue for research. Based on above that some modules of self-Q-switched all-fiber laser based on the Stimulated Brillouin Scattering (SBS) has been reported, a new type of self-Q-switched all-fiber laser based on SBS module which is simple aiming at the prior fiber laser is provided in this thesis, numerical simulation is studied, the validity of the module is identified by the experiments.In the thesis, in the first part, the features and research background of the fiber laser are introduced, several main means for Q-switching about the fiber laser are explained, and the characteristics of the self-Q-switched Er-doped fiber laser are analyzed. Secondly, the structural module of the self-Q-switched Er-doped fiber laser is designed, a detailed analysis is performed for distribution of optical power, the population inversion inside the resonance cavity of the laser combined with the Q-switching process and SBS theory.According to the numerical analysis of the laser module, the population inversion is the factor that matters greatly on the basis of the Q-switching theory. Numerical simulation in the stable state is performed at first, the results of which serve as the initial condition in the dynamic state to do the following calculation, finally, because of the results of above, the module is analyzed based on the Q-switching theory and consequently we obtain the influence of the different character parameters on the output pulse of the self-Q-switched Er-doped fiber laser based on SBS, the module is built.According to the designed structure of the fiber laser, the experimental module for further experiments is built and experiments are made. During the process of experiments, because of SBS, it is required that the signal line width is narrow and the optical power reaches the SBS threshold, two end faces of the resonance cavity respectively adopt the fiber grating and the ring interferometer. The results show that the test data accords basically to the numerical analysis, thereby the module of the laser is modified in the sense of experiment, the validity of the module is identified. Through adjusting the character parameters of the self-Q-switched Er-doped fiber laser based on SBS, with the pump power being 100mW, we obtain the output pulse of the laser with the full width at half maximum being 8ns, and the peak power being of three hundred wattages.The influence of the structure of the fiber laser on the output pulse of the laser is analyzed in this thesis in details and the work above will contribute greatly to the further research of the high-power self-Q-switched fiber laser.