High efficient XPW generation for high contrast high energy ultrashort laser pulses

The most promising approach for simultaneously having high energy and highly efficient cross polarized wave generation (XPW) resides in improving the efficiency of the single crystal setup. Smooth, flat-top like beam profiles are preferable for high conversion efficiencies and in addition, higher energy transmission in the crystal is possible due to reduced self focusing. The author demonstrates in this paper an efficient XPW generation with high energy pulses up to 3.3 mJ. The suggested configuration is based on a single BaF2 crystal XPW stage and the use of a short length, hollow core waveguide as a spatial filter to produce smooth spatial beam profiles. The setup is established to be energy-scalable, highly efficient and carrier-envelope phase (CEP) preserving. As a result of the efficient XPW generation, ultrabroad, sub-10 fs XPW pulses are also generated.