10(-10) temporal contrast for femtosecond ultraintense lasers by cross-polarized wave generation.

We take advantage of nonlinear properties associated with chi(3) tensor elements in BaF2 cubic crystal to improve the temporal contrast of femtosecond laser pulses. The technique presented is based on cross-polarized wave (XPW) generation. We have obtained a transmission efficiency of 10% and 10(-10) contrast with an input pulse in the millijoule range.