Broadband super-resolution Terahertz Time domain spectroscopy applied to Gas analysis

TL;DR

This paper introduces a super-resolution method for Terahertz Time Domain Spectroscopy that significantly enhances spectral resolution, enabling more precise and rapid gas analysis using existing broadband THz systems.

Contribution

The paper presents a novel constraint reconstruction algorithm that improves spectral resolution by a factor of 10 in THz-TDS for gas spectroscopy, overcoming traditional Fourier transform limitations.

Findings

Achieved 10-fold resolution enhancement in gas spectral lines

Demonstrated effective sparse spectrum modeling for gas analysis

Envisioned broadband, rapid, and cost-effective gas monitoring applications

Abstract

Terahertz (THz) Time domain spectroscopy (THz-TDS) is a broadband spectroscopic technique spreading its uses in multiple fields: in science from material science to biology, in industry where it measures the thickness of a paint layer during the painting operation. Using such practical commercial apparatus with broad spectrum for gas spectroscopy could be a major asset for air quality monitoring and tracking of atmospheric composition. However, gas spectroscopy needs high resolution and the usual approach in THz-TDS, where the recorded time trace is Fourier transform, suffers from resolution limitation due to the size of the delay line in the system. In this letter, we introduce the concept of constraint reconstruction for super-resolution spectroscopy based on the modeling of the spectroscopic lines in a sparse spectrum. Light molecule gas typically shows sparse and narrow lines on a broad spectrum and we propose an algorithm reconstructing these lines with a resolution improvement of 10 the ultimate resolution reachable by the apparatus. We envision the proposed technique to lead to broadband, selective, rapid and cheap gas monitoring applications.