Reducing temporal pedestal in a Ti:sapphire chirped-pulse amplification system by using a stretcher based on two concave mirrors.

We demonstrate the temporal pedestal suppression in a Ti:sapphire chirped-pulse amplification laser system. The far-field spectral phase noise can be avoided by using a stretcher based on two concave mirrors in the system, reducing the intensity and the time range of the amplified pulse’s pedestal. At the amplified energy of 1.7 J, the contrast measurement showed that the pedestal intensity was at a level of about 10−10 within a 10 ps time window near the main pulse. In the proton acceleration experiment, a 10 nm thickness CH target was irradiated by the high-contrast pulse with the focused intensity of ∼1.4×1020W/cm2, which generated a proton beam with a cutoff energy of 16 MeV.