Parallel ripple formation during femtosecond laser grooving of ceramic

Abstract

The self-organized formation of ripples in the direction parallel to the groove during the femtosecond laser machining of microgrooves on aluminum nitride ceramic at laser fluences much higher than the single-pulse ablation threshold is reported. These parallel ripples are notably different from the commonly observed polarization-perpendicular ripples and are produced in grooves having an appropriate width and depth, irrespective of laser polarization. From subsequent experiments with narrow and wide groove widths, it could be considered that the groove walls play an important role in the formation of these parallel ripples, possibly by confining the laser-induced plasma.