Optimal Design Of Tunable Single Frequency Fiber Laser Resonant Cavity

With the progress of laser technology and doped fiber emission technology, tunable single frequency fiber laser has been a main research topic for its distinct characteristics of wide-range of bandwidth, high output power, narrow linewidth, and naturally compatible with fiber. The tunable single frequency fiber laser not only provide a ideal signal carrier in high speed huge capacity Dense wavelength-division multiplexed(DWDM) fiber communication system, but also as ideal sensing & detecting source in fiber Bragg grating(FBG) based sensing system. Moreover, the wavelength detecting technology based on tunable fiber laser are hoped to become the most promising FBG sensing detecting method.The research topic of the dissertation focus on the optimal design of resonant cavity for tunable single frequency fiber laser. The main labor and the research results are as followings:⑴Specifically analyzed the theory and the key characteristics of several typical FBG, by using Matlab language, programming for simulating the reflectivity and delay spectrum, among which the uniform , phase shift, sampling FBGs are emphasized.⑵summarized the analytical expression of slope efficiency, pump threshold, and laser output power for the Er3+ doped linear cavity fiber laser, and by numerical simulation, the relation between several key parameters and the laser output characteristics are obtained.⑶After the fundamental theory of FBG based Fabry-Perot(F-P) cavity are explained, its numerical simulation and analysis are given.⑷The characteristics of chirp fiber Bragg grating(CFBG) F-P cavity are specifically discussed, the effect of key parameters such as grating length, chirp parameter, perturbation to the refractive index on the filter characteristics of CFBG F-P cavity are researched, and certain useful results are obtained as follows:①When the difference of two gratings is large enough, the transmission spectrum of CFBG F-P cavity has wide stopband, at which a single transmission peak appear that required for single mode operation;②The transmission spectrum bandwidth increases with the chirp parameter, while the transmission decreases, which leads to worse filter feature;③The cavity length will not lead to remarkable change of stopband of CFBG F-P cavity, meanwhile, single mode operation is obtained when proper cavity length is chosen.