Time- and Space-Resolved Optical Probing of Femtosecond-Laser-Driven Shock Waves in Aluminum

We present the first measurements of particle velocity histories at the interface between an aluminum sample shocked by a 120 fs laser-driven pressure pulse and a fused silica window. Frequency-domain interferometry is used to provide space- and time-resolved measurements of the phase shift of a pair of probe pulses backscattered at the shocked interface. Pressures of 1--3 Mbar are inferred from the simultaneous measurement of the particle and shock velocities along the aluminum Hugoniot curve for ~10¹⁴W/cm² laser irradiances.