Time-resolved backside optical probing of picosecond-laser-pulse-produced plasma in solid materials

We report on pump-probe measurements of reflectivity and transmissivity of a plasma produced in transparent solid materials. The plasma is created by irradiating uncoated transparent planar glass targets with 1.0-ps FWHM laser pulses at a peak intensity of 2.0×10 13 W/cm 2 Time-resolved measurements using a probe light pulse incident from the backside are presented, revealing two competing mechanisms: one is highly absorptive due to a bulk underdense plasma formed behind the target surface, and the other is highly reflective due to an overdense plasma layer at the surface