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/cm2 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.