Pump-probe imaging of femtosecond pulsed laser ablation of silicon with thermally grown oxide films

Femtosecond pulsed laser ablation of silicon substrates with thin thermally grown oxide films (20-1200 nm) was studied using pump-probe microscopy techniques. Images from both the front and side of the ablation event produced at a laser fluence of 1.3 J/cm(2) were obtained, and results from the two imaging geometries were compared yielding the optical properties of the ablated material. Ablation dynamics were studied over the time scale from 0 to 10.35 ns following the onset of ablation, and ablated material velocities ranging from 200 +/- 20 to -3010 +/- 360 m/s were determined depending on the thermal oxide film thickness.(C) 2007 American Institute of Physics.