Non-linear materials for efficient mid-IR few cycle pulse compression

A simple and cheap technique for post-compression of mid-IR laser pulses relies on nonlinear spectral broadening via SPM in mm-thick optical windows (plates) followed by recompression. Efficient broadening requires peak intensities of ~hundred GW/cm2, which in case of high average power (>10W) drivers puts serious requirements on the used optical materials’ thermal properties, purity, homogeneity, surface quality and LIDT of coatings. Several materials (YAG, fluorides, KBr, Si, ZnSe, ZnS) were tested with 3.2 µm, 13W (130 µJ, 100 kHz), 48 fs pumping. Measured nonlinear absorption, wavefront distortion, spectral broadening and long-term survival as a function of intensity will be shown.