Threshold characteristics analysis of one-end-pumped Yb3+-doped gain-guided and index-antiguided fiber laser

An exact analytical expression of the threshold pump power for the one-end-pumped Yb3+-doped gain-guided and index-antiguided (GG–IAG) fiber laser has been obtained by solving the improved rate equations (REs) with the additional leakage losses. The effects of Yb3+ concentration, fiber length, core radius and mirror reflectivity on the threshold pump power are discussed. After optimizing, the results show that the laser threshold of GG–IAG fiber laser can be greatly reduced while maintaining single mode oscillation. Compared to the numerical methods, the analytical expression has easy calculation and distinct results.

► An analytical expression of threshold for the GG–IAG fiber laser was derived.
► Fiber parameters effects on threshold are investigated.
► Lowest threshold and single mode oscillation are reached after optimizing.