Theoretical And Experimental Study Of LD Pumped High-power Yb³⁺-doped Double-clad Fibers

The research of laser diode( LD) pumped Yb³⁺-doped double-clad fiber lasers (DCFLs) is an important area of laser technology.In this dissertation, the theoretical and experimental studies of Yb³⁺-DCFLs are presented. Firstly, the historical developments,the new achievements of DCFLs are introduced. The basic structure and principle of fiber lasers,the specific energy levels and fluorescence spectrum of Yb³⁺are discussed.Secondly,the characteristics of quasi-four-level and the strongly pumped Yb³⁺-DCFLs are investigated theoretically. The formulas of the threshold pump power and output power of Yb³⁺-DCFLs have been obtained.The experimental parameters of Yb³⁺-DCFLs is studied using numerical calculation .It is shown the best parameters for high power fiber lasers, after analysis the relationship of output power with experimental parameters under different pump power.Yb³⁺-DCFLs with Fabry-Perot laser cavity are studied experimentally. The output laser power of 88W was obtained when the pump power from LD was 160 W. The slope efficiency and the optical to optical conversion efficiency are 83% and 55%, respectively.