Research Of Yb～(3+)-doped Double-clad Fiber Laser

Double-clad fiber laser can be honoured as one of the twinkling stars in fiber laser family. The clad-pumping technology helped fiber laser shake off the impression of low-power. Double-clad fiber laser syncretize the high-power and high-quality of laser beam and all of the virtues of fiber laser. In addition, it can be easily applied in optic-communications. So it draws more and more attentions. The thesis details the experiment of the Yb3+-doped double-clad fiber laser, which is pumped by Laser Diodes and works in a F-P cavity. The main theoretical and experimental researches are included in this thesis:(1) The state of the researches and the development way in the field of fiber laser worldwide are summarized based on comprehensive references reading, and the practical significance of this research subject is introduced.(2) The basic theory of fiber laser is introduced; The energy level and spectrum characteristics of Yb3+ are detailed, which indicate its superiority to emit laser; The combination of double-clad fiber and clad-pumping technology paves the way to high-power for fiber.(3) After analyze the changing of Gaussian beam, it is studied that the coupling of Gaussian beam between fibers. The general law in deciding the parameters of coupling system is deduced. A special coupling system is designed accordingly to couple LDs into the Yb3+-doped fiber.(4) The experiment of Yb3+-doped double-clad fiber laser is carried out. The process of laser naissance is observed, and several output characteristics of the laser, including longitudinal mode, power and slope efficiency are analyzed at large. The phenomenon of saturable absorber is explained. There are some problems in the experiments, then some improvement suggestions are presented.