Motivation: The key elements of the Field-Resolved Spectroscopy are powerful coherent ultrashort infrared pulses exciting molecular vibrations. The shorter the pulse, the better is the separation of the temporal fingerprint specific for the molecules in the sample from the non-resonant part of the response. To obtain such short pulses in mid-infrared range, broadband dispersive mirrors compensating GD/GDD accumulated in the ZnSe windows of the liquid cells as well as additional phase modulation in the system.
Abstract: Broadband dispersive mirrors operating in the mid-infrared spectral range 6.5-11.5 µm are developed for the first time. The mirrors comprise Ge and YbF3 layers which have not been used before for manufacturing of multilayer dispersive optics. The design and production processes are described; mechanical stresses of the coatings are estimated based on experimental data; spectral and phase properties of the produced mirrors are measured. The mirrors compensate group delay dispersion of ultrashort laser pulses accumulated by propagation through 4 mm-ZnSe windows and additional residual phase modulation of an ultrashort laser pulse.
Original publication: »Broadband dispersive Ge/YbF3 mirrors for mid-infrared spectral range« (Optics Letters 44, 5210 (2019))