Self-focusing propagation of ultra-short ultra-intense laser in under-dense plasmas

Experiments have been performed using ultra-short (30 fs) ultra-intense laser pulse (up to 1018 W/cm2) focused into under-dense plasmas. A probe pulse was used for the shadowgraphy and the investigation on the propagation of laser under various conditions was presented. The results demonstrate that relativistic effect is the main self-focusing regime and the ratio of laser power to critical power is the key condition for self-focusing of the ultra-short ultra-intense laser in under-dense plasmas.