Nonlinear interferometer for Fourier-transform mid-infrared gas spectroscopy using near-infrared detection

TL;DR

This paper introduces a nonlinear interferometer technique for mid-infrared gas spectroscopy that uses near-infrared detection and Fourier-transform analysis, achieving high spectral resolution and enabling detailed molecular analysis.

Contribution

The work demonstrates a novel approach combining nonlinear interferometry with Fourier-transform analysis for high-resolution mid-infrared spectroscopy using near-infrared detection.

Findings

Achieved sub-wavenumber spectral resolution for gas spectroscopy.

Demonstrated rotational-line-resolving spectroscopy of methane.

Identified noise limitations and transmission accuracy of the device.

Abstract

Nonlinear interferometers allow for mid-infrared spectroscopy with near-infrared detection using correlated photons. Previous implementations have demonstrated a spectral resolution limited by spectrally selective detection. In our work, we demonstrate mid-infrared transmission spectroscopy in a nonlinear interferometer using single-pixel near-infrared detection and Fourier-transform analysis. A sub-wavenumber spectral resolution allows for rotational-line-resolving spectroscopy of gaseous samples in a spectral bandwidth of over 700$\,$cm$^{-1}$. We use methane transmission spectra around 3.3$\,\mu$m wavelength to characterize the spectral resolution, noise limitations and transmission accuracy of our device. The combination of nonlinear interferometry and Fourier-transform analysis paves the way towards performant and efficient mid-infrared spectroscopy with near-infrared detection.