Approximate analytical solutions to rate equations ofmulti-position-pumped fiber lasers

In order to analyze the characteristics of multi-position pumped fiber laser expediently,the predominant part of the re-emission was adopted to improve the solutions precise,and the rate equations describing the Yb-doped multi-position pumped fiber lasers were solved analytically.The solutions of the output power of the fiber lasers were got approximately.Comparing the analytical solutions and the numerical solutions,the result shows the difference between them is small than 5%.Based on the relationship between the position of the pump point and the utilization efficiency of pump light,the conclusion was drawn that pump sources should be set near the fiber ends.Simulating the distribution of pump light along the fiber of the two schemes(one-position-pump and multi-position-pump),the results show that for the multi-position-pump scheme,the distribution of pump power is relatively uniform along the fiber compared to that of the one-position-pump scheme.In other words,extra local temperature rise arising from the absorption of the external cald can be reduced in the multi-position-pump scheme,rendering it a better choice for the high power fiber lasers.