Mid-Infrared Frequency Comb Fourier Transform Spectrometer

TL;DR

This paper introduces a novel mid-infrared frequency comb Fourier transform spectrometer capable of rapid, high-resolution, and sensitive molecular detection across a broad spectral range, advancing spectroscopic applications.

Contribution

It presents the first operational mid-infrared frequency comb Fourier transform spectrometer with high resolution and broadband capabilities, enabling real-time molecular analysis.

Findings

Achieved 0.0056 cm-1 spectral resolution.

Detected molecules at parts-per-billion levels within 30 seconds.

Enabled precise measurements in complex gas mixtures.

Abstract

Optical frequency-comb-based-high-resolution spectrometers offer enormous potential for spectroscopic applications. Although various implementations have been demonstrated, the lack of suitable mid-infrared comb sources has impeded explorations of molecular fingerprinting. Here we present for the first time a frequency-comb Fourier transform spectrometer operating in the 2100-to-3700-cm-1 spectral region that allows fast and simultaneous acquisitions of broadband absorption spectra with up to 0.0056 cm-1 resolution. We demonstrate part-per-billion detection limits in 30 seconds of integration time for various important molecules including methane, ethane, isoprene, and nitrous oxide. Our system enables precise concentration measurements even in gas mixtures that exhibit continuous absorption bands, and it allows detection of molecules at levels below the noise floor via simultaneous analysis of multiple spectral features. This system represents a near real-time, high-resolution, high-bandwidth mid-infrared spectrometer which is ready to replace traditional Fourier transform spectrometers for many applications in trace gas detection, atmospheric science, and medical diagnostics.