Study On LD Pumped Ytterbium(Yb～(3+))-doped Fiber Laser And Its Frequency-doubling Characteristics

Recently,as the representation of the third laser technology,fiber lasers arouse people's great interests in the laser field,which have also become the leader of improving traditional laser performances and reforming laser industries completely. Theoretical and experimental research of the Yb³⁺-doped double-clad fiber laser were presented in the dissertation as the main part,finally the frequency-doubling characteristics of fiber laser were discussed simply. The main subjects are as follows:1. The fiber laser's developmental history is reviewed,and its advantages, main applications, research progresses and developing trends are introduced and summarized.2. The basic structure and principle of Yb³⁺-doped double-clad fiber laser are discussed through analysing the characteristics of Yb³⁺-doped double-clad fiber and summarizing fiber laser's cavity technology and its pumping structures.3. The Yb³⁺-doped double-clad fiber laser with Fabry-Perot cavity is theoretically researched and numerically simulated. Deriving from the rate equations, the analytic expressions of pumping-power distribution, laser output power, threshold power and slope-efficiency of the fiber laser are obtained, which are numerically simulated with Matlab software. According to the simulated results, the influences of pumping modes,cavity-mirror reflectivity, fiber length and so on towards the performance of fiber laser are discussed in great detail, which providing important theoretical guidance for experiment and optimum design of fiber laser system.4. The experiment of LD pumped Yb³⁺-doped double-clad fiber laser with F-P cavity is carried out based on theoretical analyses. Under the maximum pumping power of 8.86W, the near single-mode fiber-laser ouput at 1081.3nm with maximal power of 4.12W is obtained, and the optical-to-optical efficiency is 46.5%, the slope efficiency is 61.9% and the total conversion efficiency is 29.6%. Experimental results accord with theoretical conclusions.5. The frequency-doubling characteristics of the Yb³⁺-doped double-clad fiber laser are investigated. The green laser output at 540.1nm with 27mW is realized through the frequency-doubling structure of fiber laser designed independently, which proves the feasibility of this structure and CW fiber laser's frequency doubling.6. The last part is the summarization and prospect of the dissertation.