Soliton frequency comb generation in a low Q microcavity coupled to a gain microcavity

TL;DR

This paper explores how an amplifying auxiliary cavity influences soliton frequency comb generation in low Q microcavities, offering insights into reducing fabrication complexity and expanding material platforms.

Contribution

It provides a theoretical and experimental analysis of gain effects on bistability and soliton comb generation in coupled microcavities, highlighting conditions for successful comb formation.

Findings

Small gain in auxiliary cavity aids soliton generation in low Q microcavities.

Excessive gain prevents dissipative soliton formation.

Guides design of chip-scale integrated optical frequency combs.

Abstract

Soliton frequency comb generation in coupled nonlinear microcavities is attractive because a coupled microcavity offers more flexibility and possibilities compared to a single nonlinear microcavity. In this paper, we investigate how an amplifying auxiliary cavity affects the bistability region of the main cavity and soliton frequency comb generation. When the auxiliary cavity has a small gain, it can partially compensate for the loss of the main cavity allowing the generation of soliton combs with a relatively low Q-factor in the main cavity. A low Q-factor microcavity would reduce the difficulty of fabrication and extend the microcavity platform to different types of materials. However, if the gain of the auxiliary cavity is too large, a frequency comb cannot be generated because the coupled nonlinear microcavity system is no longer dissipative. Our results provide a theoretical understanding and experimental guidance for the bistability region and soliton frequency comb generation in coupled nonlinear microcavities with an amplifying auxiliary cavity. The results will facilitate the development of chip-scale integrated optical frequency comb sources.