Picosecond laser sputtering of sapphire at 266 nm

Abstract

We observe that 266 nm laser pulses of 30 ps duration and fluence near 10 J/cm2 causes reproducible surface sputtering and etching of crystalline sapphire in air. The etching rate for the initial ten pulses is relatively slow, 0.04 μm/pulse, producing a smooth surface of the etched area and a broad-angle plume emission. After some 20 pulses, the etching rate is dramatically faster, 0.5 μm/pulse, producing a rough etched surface and a plume composed of broad-angle emission as well as a narrow perpendicular jet emission. Micron-sized depressions can be made on the sapphire with no visible damage or cracking to the surroundings.