NANOSECOND AND FEMTOSECOND EXCIMER-LASER ABLATION OF OXIDE CERAMICS

The uv laser-ablation behaviour of various oxide ceramics (Al2O3, MgO, ZrO2) has been studied using different wavelengths (248 nm, 308 nm) and pulse durations (30 ns, 500 fs). Time-resolved absorption measurements of the sample and the ablation plume during ablation were performed. Using sub-ps pulses the ablation threshold fluence is generally lower than for ns pulses; the ablation rate is higher in the whole investigated fluence range up to 20 J/cm(2). The study of the morphology of the ablation structures and the results of the absorption experiments lead to the conclusion that different ablation mechanisms are involved. Using ns pulses ''plasma mediated ablation'' is dominating, whereas in the fs case the process is controlled by multi-photon absorption enabling microstructuring of the material.