# Lock-in-detection dual-comb spectroscopy

## TL;DR

This paper introduces LID-DCS, a novel dual-comb spectroscopy method combining lock-in detection to directly extract specific optical frequency comb modes, enabling faster and more efficient gas spectroscopy and transient signal monitoring.

## Contribution

The paper presents a new frequency-domain dual-comb spectroscopy technique that eliminates the need for FFT, improving speed and efficiency in gas analysis.

## Key findings

- LID-DCS effectively extracts specific OFC modes without FFT.
- Demonstrated rapid monitoring of transient signals.
- Successfully applied to hydrogen cyanide gas spectroscopy.

## Abstract

Dual-comb spectroscopy (DCS) is useful for gas spectroscopy due to high potential of optical frequency comb (OFC). However, fast Fourier transform (FFT) calculation of a huge amount of temporal data spends significantly longer time than the acquisition time of an interferogram. In this article, we demonstrate frequency-domain DCS by a combination of DCS with lock-in detection, namely LID-DCS. LID-DCS directly extracts an arbitrary OFC mode from a vast number of OFC modes without the need for FFT calculation. Usefulness of LID-DCS is demonstrated in rapid monitoring of transient signal change and spectroscopy of hydrogen cyanide gas.

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Source: https://tomesphere.com/paper/1904.03415