Theorical Study Of LD Pumped Double-cladding Yb～(3+)-doped Fiber Laser

The theory and technology research of laser Diode (LD) pumped Yb3+-doped double-clad fiber laser is the currently ultimate branch in the laser techniques field. This dissertation has made theoretical study closely around the characteristics of Yb3+-doped double-clad fiber laser .the main achievements of this dissertation are as follows:Firstly, the paper introduces the historical developments, the new achievements of the double-clad fiber laser, as well as the basic structure and principle of fiber laser are explained, and the specific energy level and fluorescence spectrum of Yb3+ are introduced.Secondly, the theoretical study that relates to the characteristic of quasi-four-level and the strongly pumped Yb3+-doped double-clad fiber lasers is investigated. The relation between threshold and radius of pumping light and laser light is concluded. The expressions ofoutput power, slope efficiency and small-signal gain of double-clad fiber lasers have been given.Finally, The characteristic of Yb3+-doped double-clad fiber laser was numerically studied with MATLAB. The effect of the dimension of pumping light and laser light ,cavity, fiber length, reflection, ratio of output mirror, modes of pump on the characteristic of the fiber laser are investigated. These discussions provided a theoretical basis to the optimum design of LD pumped double-clad fiber laser.