High rate deep channel ablative formation by picosecond-nanosecond combined laser pulses

Temporally profiled pulsed radiation of the Nd:YAG laser was applied to drilling and micromachining of ceramics, steel, and CVD diamond, demonstrating one or two orders of magnitude enhancement of ablation rates compared to conventional pico- and nanosecond-pulsed ablation at the same energy density. The developed laser system delivered combined pulses consisting of a picosecond pulse train followed by a nanosecond pulse train. The combination of picosecond and nanosecond components within one laser shot turned out to be especially beneficial for high-aspect-ratio channel formation. Polarization dependence of the ablated deep crater morphology was observed in AlN samples. Waveguide radiation propagation in self-made deep channels as well as the influence of high-temperature laser-produced plasma on this phenomena are discussed.