Unifying frequency combs in active and passive cavities: Temporal solitons in externally-driven ring lasers

TL;DR

This paper introduces a unified theoretical framework for frequency combs in active and passive optical cavities, demonstrating the existence of temporal solitons in externally-driven semiconductor ring lasers, a phenomenon previously observed only in microresonators.

Contribution

The authors develop a general equation that unifies the description of active and passive cavities, including hybrid devices like externally-driven semiconductor ring lasers, revealing new soliton phenomena.

Findings

Unified equation for active and passive cavities

Existence of temporal solitons in externally-driven ring lasers

Symmetry breaking and self-localization phenomena observed

Abstract

Frequency combs have become a prominent research area in optics. Of particular interest as integrated comb technology are chip-scale sources, such as semiconductor lasers and microresonators, which consist of resonators embedding a nonlinear medium either with or without population inversion. Such active and passive cavities were so far treated distinctly. Here we propose a formal unification by introducing a general equation that describes both types of cavities. The equation also captures the physics of a hybrid device - a semiconductor ring laser with an external optical drive - in which we show the existence of temporal solitons, previously identified only in microresonators, thanks to symmetry breaking and self-localization phenomena typical of spatially-extended dissipative systems.