Higher order mode suppression in high-Q anomalous dispersion SiN microresonators for temporal dissipative Kerr soliton formation

TL;DR

This paper introduces a method to suppress higher order modes in high-Q silicon nitride microresonators, enabling stable dissipative Kerr soliton formation by using a single mode filtering section to prevent avoided crossings.

Contribution

The authors demonstrate a novel single mode filtering technique inside high-Q SiN microresonators that suppresses avoided crossings without compromising the quality factor, facilitating soliton generation.

Findings

Efficient suppression of avoided crossings in SiN microresonators.

Successful formation of single dissipative Kerr solitons.

High quality factors maintained during mode filtering.

Abstract

High-Q silicon nitride (SiN) microresonators enable optical Kerr frequency comb generation on a photonic chip and have recently been shown to support fully coherent combs based on temporal dissipative Kerr soliton formation. For bright soliton formation it is necessary to operate SiN waveguides in the multimode regime so as to produce anomalous group velocity dispersion. This can lead to local disturbances of the dispersion due to avoided crossings caused by coupling between different mode families, and therefore prevent the soliton formation. Here we demonstrate that a single mode "filtering" section inside high-Q resonators enables to efficiently suppress avoided crossings, while preserving high quality factors (Q~10^6). We demonstrate the approach by single soliton formation in SiN resonators with filtering section.