Group Delay Dispersion Measurements of Novel Mid-Infrared Mirrors

Novel monocrystalline and amorphous-crystalline hybrid supermirrors for the mid-infrared (MIR) spectral regime exhibit outstanding performance regarding absorption and scatter loss [1], [2], recently culminating in optical resonators with a two-mirror-cavity finesse of 231 000 and 409 000 at a center wavelength of 4.45 μm for an all-crystalline and hybrid design, respectively [3]. Possible applications of such supermirrors range from precision molecular spectroscopy to gravitational wave detection [4], [5]. As many MIR applications use broadband frequency combs, it is essential to investigate and optimize the group delay dispersion (GDD) of these novel mirrors.