10^?10 temporal contrast for femtosecond ultraintense lasers by cross-polarized wave generation

TLDR

The authors aim to enhance femtosecond laser pulse temporal contrast by exploiting the third‑order nonlinear response of BaF₂ cubic crystals. They achieve this via cross‑polarized wave generation, where contrast improvement is limited only by the extinction ratio of the polarization discriminator. The XPW filter delivers 10 % transmission, 10¹⁰ contrast for millijoule pulses, preserves spectral shape and phase, and also serves as an efficient spatial filter.

Abstract

We take advantage of nonlinear properties associated with ?(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. This filter does not affect the spectral shape or the phase of the cleaned pulse. It also acts as an efficient spatial filter. In this method the contrast enhancement is limited only by the extinction ratio of the polarization discrimination device.