Normal-dispersion Microcombs Enabled by Controllable Mode Interactions

TL;DR

This paper presents a controllable scheme using coupled microresonators with microheaters to generate broadband normal-dispersion microcombs, expanding the potential wavelength range for microcomb applications.

Contribution

It introduces a novel method to programmatically tune mode interactions in coupled microresonators for Kerr microcomb generation in the normal dispersion regime.

Findings

Demonstrated broadband normal-dispersion microcombs using controllable mode interactions

Achieved microcomb generation, repetition rate selection, and mode locking with silicon nitride microrings

Showed potential for extending microcomb wavelength ranges, including visible spectrum

Abstract

We demonstrate a scheme incorporating dual coupled microresonators through which mode interactions are intentionally introduced and controlled for Kerr frequency comb (microcomb) generation in the normal dispersion region. Microcomb generation, repetition rate selection, and mode locking are achieved with coupled silicon nitride microrings controlled via an on-chip microheater. Our results show for the first time that mode interactions can be programmably tuned to facilitate broadband normal-dispersion microcombs. The proposed scheme increases freedom in microresonator design and may make it possible to generate microcombs in an extended wavelength range (e.g., in the visible) where normal material dispersion is likely to dominate.