Soliton regulation in microcavities induced by fundamental-second-harmonic mode coupling

TL;DR

This paper demonstrates how fundamental-second-harmonic mode coupling in microcavities can induce deterministic soliton regulation, improving control over soliton formation in broadband comb sources with combined nonlinearities.

Contribution

It reveals the role of FD-SH mode coupling in controlling soliton dynamics, providing new insights for designing broadband microcomb sources with $ ext{chi}^{(2)}$ and $ ext{chi}^{(3)}$ nonlinearities.

Findings

FD-SH mode coupling leads to more deterministic soliton formation.

Phase matching and coupling strength influence soliton behavior.

The study offers guidance for broadband soliton comb generation.

Abstract

Microcomb generation with simultaneous $\chi^{(2)}$ and $\chi^{(3)}$ nonlinearities brings new possibilities for ultra-broadband and potentially self-referenced integrated comb sources. However, the evolution of the intracavity field involving multiple nonlinear processes shows complex dynamics that is still poorly understood. Here we report on strong soliton regulation induced by fundamental-second-harmonic (FD-SH) mode coupling. The formation of solitons from chaos is extensively investigated based on coupled Lugiato-Lefever equations. The soliton generation shows more deterministic behaviors in the presence of FD-SH mode interaction, in sharp contrast to the usual cases where the soliton number and relative locations are stochastic. Deterministic single soliton transition, soliton binding and prohibition are observed, depending on the phase matching condition and coupling coefficient between the fundamental and second-harmonic waves. Our finding provides important new insights into the soliton dynamics in microcavities with simultaneous $\chi^{(2)}$ and $\chi^{(3)}$ nonlinearities, and can be immediate guidance for broadband soliton comb generation with such platforms.