Group Delay Dispersion Measurements on Mid‐Infrared Supermirrors

Abstract Methods and results for broadband group delay dispersion measurements of monocrystalline and amorphous‐crystalline hybrid supermirrors, as well as an all‐amorphous mirror, are presented. Measurements are performed with a custom‐built white light interferometer covering a spectral range from 2.5 to 4.8 , capable of measuring in both balanced and unbalanced measurement configuration. The results are compared with theoretical transfer‐matrix method simulations and an independent measurement using a commercial Fourier‐transform infrared spectrometer. Additionally, group delay dispersion is investigated by direct differentiation using a local polynomial smoothing approach (Savitzky‐Golay filter), and strong consistency is observed between the measurement results, the theoretical prediction, and the estimation using this method.