The optimum length of linear cavity Yb3+-doped double-clad fiber laser

In order to improve the performance of the double-clad fiber laser, the optimum laser length needs to be estimated prior to the experiment. Previous expressions for the optimum length of fiber laser have been established under some assumptions, such as the output power without laser scattering loss and the pump power without reflection in the output-end. In this work, the issue of optimum laser length has been analyzed theoretically based on the strongly pumped fiber laser model. An extended expression for the optimum length of the linear cavity Yb3+-doped double-clad fiber laser is obtained. The respective effects of the laser scattering loss, the pump power, the Yb3+ dopant concentration, and the pump reflection on the optimum laser length are identified.