Overcoming the noise-tracking-bandwidth limits in Free-running Dual-Comb Interferometry

TL;DR

This paper introduces a simple method to significantly increase the noise-tracking bandwidth in free-running dual-comb interferometry, enabling broader spectral acquisition without sacrificing resolution, demonstrated through spectroscopy of a gas cell.

Contribution

The authors propose a novel architecture utilizing coherent-harmonic-enhanced spectroscopy to extend noise-tracking bandwidth, decoupling it from repetition rate differences, which is a new approach in dual-comb interferometry.

Findings

Achieved a 20-fold increase in tracking bandwidth.

Maintained spectral resolution of 12.5 MHz.

Demonstrated effectiveness with gas cell spectroscopy.

Abstract

We present a straightforward method to extend the noise-tracking bandwidth for self-correction algorithms in free-running dual-comb interferometry, leveraging coherent-harmonic-enhanced dual-comb spectroscopy. As a proof of concept, we employed both this novel architecture and a conventional one to perform free-running dual-comb spectroscopy of a $\text{H}^{13}\text{C}^{14}\text{N}$ gas cell, demonstrating a 20-fold increase in tracking bandwidth at the same spectral resolution of 12.5 MHz. Since this approach improves the tracking bandwidth by generating harmonic centerbursts within an interferogram period, it decouples the tracking bandwidth from the repetition rate difference, thus avoiding spectral acquisition bandwidth narrowing. This significantly broadens the outlook for free-running dual-comb spectroscopy.