Phased-Locked Two-Color Single Soliton Microcombs in Dispersion-Engineered Si3N4 Resonators

TL;DR

This paper introduces a novel dispersion-engineered Si3N4 microring resonator capable of supporting phase-locked two-color soliton microcombs, enabling broad spectral coverage from visible to infrared for advanced optical applications.

Contribution

It presents a new resonator design that supports phase-locked two-color soliton states with controllable spectral windows, expanding the capabilities of microcomb generation.

Findings

Supports phase-locked two-color soliton states

Spectral windows can be tailored from 750 nm to 3000 nm

Design is robust to parameter variations

Abstract

We propose and theoretically investigate a dispersion-engineered Si3N4 microring resonator, based on a cross-section containing a partially-etched trench, that supports phase-locked, two-color soliton microcomb states. These soliton states consist of a single circulating intracavity pulse with a modulated envelope that sits on a continuous wave background. Such temporal waveforms produce a frequency comb whose spectrum is spread over two widely-spaced spectral windows, each exhibiting a squared hyperbolic secant envelope, with the two windows phase-locked to each other via Cherenkov radiation. The first spectral window is centered around the 1550 nm pump, while the second spectral window is tailored based on straightforward geometric control, and can be centered as short as 750 nm and as long as 3000 nm. We numerically analyze the robustness of the design to parameter variation, and consider its implications to self-referencing and visible wavelength comb generation.