Kunz, JachinJachinKunzLindner, ChiaraChiaraLindnerHerr, SimonSimonHerrWolf, SebastianSebastianWolfKießling, JensJensKießlingKühnemann, FrankFrankKühnemann2023-03-132023-03-132023https://publica.fraunhofer.de/handle/publica/43758910.1117/12.2650157Nonlinear interferometers based on correlated photon pairs allow mid-infrared spectroscopy by measuring only near-infrared photons with a silicon-based detector, which offers higher detectivities than mid-infrared detectors. Here, we use the nonlinear interferometer not only to determine the transmission of a sample but also for spectral analysis - analogue to classical Fourier transform infrared (FTIR) spectrometers. The Quantum FTIR analyzes the absorption of gas mixtures with high spectral resolution over a broad mid-infrared wavelength range. Improved emission rates of the photon pair source yield sensitivities similar to a classical FTIR despite an extremely low light exposure on the sample.enNonlinear interferometerSPDCCorrelated photonsQFTIRconference paper