Average soliton dynamics of a high-gain erbium fiber laser

Soliton propagation in a fiber described by the nonlinear Schrödinger equation in the presence of large periodic energy variations is examined. Stable propagation can be achieved provided that the soliton period is long compared with the period of energy variation and the (associated) average soliton (peak) pulse power equals the fundamental soliton (peak) pulse power. The result is used to interpret recent experiments on mode-locked, high-gain erbium fiber lasers.