Direct amplification of picosecond pulses in neodymium glass with a power density above 100 GW cm-2

A scheme for amplification of ultrashort laser pulses is studied, which is used in experiments on symmetrisation of ablation pressure with the help of a prepulse upon acceleration of foils by laser radiation of high brightness. The possibility of direct amplification of short pulses before their expansion in order to increase the energy contrast is considered. In experiments performed on the PICO facility, the amplification of a 10-ps pulse with a power density exceeding 100 GW cm^-2 is demonstrated with the gain equal to 1.2 and the inversion drop above 30 %.