Temporal contrast improvement by a self-diffraction process for a petawatt-class Ti:sapphire laser

Abstract

We demonstrate significant temporal contrast improvement for a petawatt-class Ti:sapphire femtosecond laser by introducing a temporal pulse filter based on a self-diffraction process. A double chirped-pulse-amplification laser system was set up to stretch, amplify and recompress the generated first-order self-diffraction pulse. The maximum energy of 130 μJ has been achieved for one first-order self-diffraction seed pulse. By optimizing the initial chirp value, the spectral bandwidth was slightly broadened for the first-order self-diffraction pulse and the cleaned pulse did not exhibit visible spectral distortions in the air environment. The measurement results for the incident pulse and the recompressed first-order self-diffraction pulse showed that the temporal contrast was improved by seven orders of magnitude, i.e. from ∼105 to ∼1012 at −25 ps before the main pulse. Such a temporal contrast is beneficial for laser-matter interaction experiments with high focused intensity up to 1022 W/cm2.