Maximum soliton-train duty cycle in harmonically mode-locked fiber lasers

We analyze the main methods for high-repetition-rate soliton generation in fiber lasers in view of the applications to fiber transmission. Particular emphasis is given to the problem of intracavity soliton interactions and stabilization methods. Because of the interactions we find that the maximum duty cycle achievable in a soliton source is 0.22. We also find that the relative phase difference between adjacent solitons may be controlled by means of an intracavity étalon, whereas without the étalon the solitons are stable only when they are out of phase. Moreover the introduction of the intracavity étalon has led to a strong reduction in the fluctuations of the soliton parameters induced by quantum noise.