Nonlinear interferometers for broadband mid-infrared spectroscopy

Mid-Infrared spectroscopy is one of the most important techniques in chemical analysis. However, the detectors for the mid-infrared range suffer from lower specific detectivities in comparison to their visible counterparts, cost more and often require cryogenic cooling. Nonlinear interferometers allow measuring mid-infrared spectra by detecting visible light using the induced coherence effect. In our work, we realize a nonlinear interferometer designed for broadband mid-infrared spectra with high resolution, which is easily tuneable, and in analogy to classical Fourier transform infrared (FTIR) spectrometers requires no additional spectral selection.