The Analysis and the Theoretical Calculation of Yb3+ Doped Double-clad Fiber Laser

The energy level structure of Yb3+ is analyzed, and a theoretical model is established. The influence of pumping power, fiber length, reflectance of cavity mirror and other related parameters on the performance of the laser is analyzed. The maximum output power can be achieved at a certain reflectance. The higher the input pump power, the smaller the reflectance of the rear mirror which obtains the maximum output power. For different pumping wavelengths, the optimal length of the gain fiber is not the same, and it is also different from the optimal length determined by the minimum pumping threshold. Therefore, in the design of fiber lasers, we should consider comprehensively to determine the appropriate fiber length. Reducing inner raduis is beneficial to improving slope efficiency when the characteristics of the fiber itself remain unchanged.