Design of Partially Etched GaP-OI Microresonators for Two-Color Kerr Soliton Generation at NIR and MIR

TL;DR

This paper designs a GaP-OI microresonator with a partial etch to generate two-color Kerr soliton frequency combs spanning near-infrared and mid-infrared spectra, demonstrating flexible dispersion engineering.

Contribution

It introduces a novel partially-etched GaP-OI microresonator design enabling dual spectral span Kerr soliton generation with tunable dispersion properties.

Findings

Achieves a 3.25 μm wide anomalous dispersion spectral span

Numerically generates two Kerr soliton combs with ~100 GHz spacing

Demonstrates design flexibility for multicolor frequency combs

Abstract

We present and theoretically investigate a dispersion engineered GaP-OI microresonator containing a partially-etched gap of 250 nm x 410 nm in a 600 nm x 2990 nm waveguide. This gap enables a 3.25 {\mu}m wide anomalous dispersion spectral span covering both the near-infrared and the mid-infrared spectra. This anomalous dispersion is manifested by two mechanisms, being the hybridization of the fundamental TE modes around 1550 nm and the geometric dispersion of the higher order TE mode around the 3100 nm wavelengths, respectively. Two Kerr soliton combs can be numerically generated with 101 GHz and 97 GHz teeth spacings at these spectral windows. The proposed structure demonstrates the design flexibility thanks to the partially etched gap and paves the way towards potential coherent multicolor frequency comb generation in the emerging GaP-OI platform.