Wolf, SebastianSebastianWolfKießling, JensJensKießlingKunz, MichaelMichaelKunzPopko, GregorGregorPopkoBuse, KarstenKarstenBuseKühnemann, FrankFrankKühnemann2022-03-052022-03-052017https://publica.fraunhofer.de/handle/publica/24868310.1364/OE.25.014504Mid-infrared spectroscopy is an essential analytical method in science and industry. Unlike in the near-infrared range, grating spectrometers for the mid-infrared are rarely employed, mostly due to the limited availability and performance of suitable line array detectors. In this work, continuous-wave nonlinear-optical upconversion is used to enable mid-infrared spectroscopy. A broad spectral window between 3.7 and 4.7 mm is upconverted to 825 - 867 nm for detection on a silicon-camera-based near-infrared grating spectrometer with a high sensitivity down to sub-picowatt of input power. A theoretical model is presented that accurately describes the upconversion process and the total system behavior. Spectroscopic flame emission measurements demonstrate the applicability towards the analysis of highly dynamic processes.enupconversionspectrometersspectroscopyinfraredinfrared spectroscopy621journal article