The Theoretical Calculation and Influencing Factors of Yb3+ Doped Double-Clad Fiber Laser

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