Lindner, ChiaraChiaraLindnerKunz, JachinJachinKunzHerr, Simon J.Simon J.HerrWolf, SebastianSebastianWolfKießling, JensJensKießlingKühnemann, FrankFrankKühnemann2022-03-062022-03-062021https://publica.fraunhofer.de/handle/publica/26592510.1364/OE.415365Nonlinear 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 mm 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.endiode pumped laserFourier Transform InterferometryNear Infrared Spetroscopyoptical coherence tomographyphotonvisible light621journal article