Self-starting stable coherent mode-locking in a two-section laser

TL;DR

This paper demonstrates that a stable, self-starting coherent mode-locking regime can be achieved in a simple two-section ring-cavity laser by proper cavity length selection, leveraging finite-cavity-size effects for stabilization.

Contribution

It introduces a novel self-starting coherent mode-locking regime in a simple two-section laser, previously thought non-self-starting, through cavity length optimization.

Findings

Stable CML regime achieved in a simple two-section cavity.

Regime self-develops from non-lasing state without external seeding.

Finite-cavity-size effects stabilize the pulsed operation.

Abstract

Coherent mode-locking (CML) uses self-induced transparency (SIT) soliton formation to achieve, in contrast to conventional schemes based on absorption saturation, the pulse durations below the limit allowed by the gain line width. Despite of the great promise it is difficult to realize it experimentally because a complicated setup is required. In all previous theoretical considerations CML is believed to be non-self-starting. In this article we show that if the cavity length is selected properly, a very stable (CML) regime can be realized in an elementary two-section ring-cavity geometry, and this regime is self-developing from the non-lasing state. The stability of the pulsed regime is the result of a dynamical stabilization mechanism arising due to finite-cavity-size effects.