Green, red and IR frequency comb line generation from single IR pump in AlN microring resonator

TL;DR

This paper demonstrates on-chip visible frequency comb generation from a single infrared pump using an aluminum nitride microring resonator, enabling compact broadband sources for spectroscopy.

Contribution

It introduces a novel method for generating visible frequency lines via harmonic and sum frequency conversion in a single aluminum nitride microcomb device.

Findings

Visible frequency lines generated through second, third harmonic, and sum frequency conversion.

High-resolution spectroscopy confirms matched free spectral range across bands.

Cascaded frequency conversions enable potential for self-referenced combs.

Abstract

On-chip frequency comb generations enable compact broadband sources for spectroscopic sensing and precision spectroscopy. Recent microcomb studies focus on infrared spectral regime and have difficulty in accessing visible regime. Here, we demonstrate comb-like visible frequency line generation through second, third harmonic, and sum frequency conversion of a Kerr comb within a high Q aluminum nitride microring resonator pumped by a single telecom laser. The strong power enhancement, in conjunction with the unique combination of Pockels and Kerr optical nonlinearity of aluminum nitride, leads to cascaded frequency conversions in the visible spectrum. High-resolution spectroscopic study of the visible frequency lines indicates matched free spectrum range over all the bands. This frequency doubling and tripling effect in a single microcomb structure offers great potential for comb spectroscopy and self-referencing comb.