Mechanism of multisoliton formation and soliton energy quantization in passively mode-locked fiber lasers

TL;DR

This paper uses numerical simulations to explore how multiple solitons form and how their energies become quantized in passively mode-locked fiber lasers, revealing the underlying mechanisms involving peak power limiting and gain competition.

Contribution

It uncovers the mechanisms behind multi-soliton formation and energy quantization in fiber lasers, linking these phenomena to peak power limiting and gain competition effects.

Findings

Multiple solitons are caused by peak power limiting in the laser cavity.

Soliton energy quantization results from gain competition among solitons.

The mechanisms may be similar in other types of soliton fiber lasers.

Abstract

We report results of numerical simulations on the multiple soliton generation and soliton energy quantization in a soliton fiber ring laser passively mode-locked by using the nonlinear polarization rotation technique. We found numerically that the formation of multiple solitons in the laser is caused by a peak power limiting effect of the laser cavity. It is also the same effect that suppresses the soliton pulse collapse, an intrinsic feature of solitons propagating in the gain media, and makes the solitons stable in the laser. Furthermore, we show that the soliton energy quantization observed in the lasers is a natural consequence of the gain competition between the multiple solitons. Enlightened by the numerical result we speculate that the multi-soliton formation and soliton energy quantization observed in other types of soliton fiber lasers could have similar mechanism.