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) a nd pulse durations (30 ns, 500 fs). Time-resolved absorption measureme nts of the sample and the ablation plume during ablation were performe d. Using sub-ps pulses the ablation threshold fluence is generally low er than for ns pulses; the ablation rate is higher in the whole invest igated 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 en abling microstructuring of the material.