High-resolution mid-IR spectrometer based on frequency upconversion

We demonstrate a novel approach for high-resolution spectroscopy based on frequency upconversion and postfiltering by means of a scanning Fabry–Perot interferometer. The system is based on sum-frequency mixing, shifting the spectral content from the mid-infrared to the near-visible region allowing for direct detection with a silicon-based CCD camera. This approach allows for low noise detection even without cooling of the detector. A setup is realized for the 3 μm regime with a spectral resolution of 0.2 nm using lithium niobate as the nonlinear material and mixing with a single-frequency 1064 nm laser. We investigate water vapor emission lines from a butane burner and compare the measured results to model data. The presented method we suggest to be used for real-time monitoring of specific gas lines and reference signals.