Microresonator-based high-resolution gas spectroscopy

TL;DR

This paper demonstrates a high-resolution, chip-based gas spectroscopy technique using a microresonator frequency comb with mode-hop-free tuning over 16 GHz, enabling detailed molecular fingerprinting in the mid-IR.

Contribution

It introduces a novel method for tuning microresonator-based frequency combs over 16 GHz, achieving high spectral resolution for gas-phase spectroscopy on a chip.

Findings

Achieved mode-hop-free tuning over 16 GHz.

Demonstrated gas fingerprinting of acetylene with <80 MHz resolution.

Operated over a 45-THz optical bandwidth in mid-IR.

Abstract

In recent years, microresonator-based optical frequency combs have created up opportunities for developing a spectroscopy laboratory on a chip due to its broadband emission and high comb power. However, with mode spacings typically in the range of 10 - 1000 GHz, the realization of a chip-based high-resolution spectrometer suitable for gas-phase spectroscopy has proven to be difficult. Here, we show mode-hop-free tuning of a microresonator-based frequency comb over 16 GHz by simultaneously tuning both the pump laser and the cavity resonance. We illustrate the power of this scanning technique by demonstrating gas-phase molecular fingerprinting of acetylene with a high-spectral-resolution of < 80 MHz over a 45-THz optical bandwidth in the mid-IR. Our technique represents a significant step towards on-chip gas sensing with an ultimate spectral resolution given by the comb linewidth.