Selective etching of 10 MHz repetition rate fs-laser inscribed tracks in YAG

Abstract

We investigated fs-laser structuring of YAG crystals at high writing velocities up to 100 mm/s using a commercial 10 MHz fs-laser system supplied by Coherent Inc. and selective etching of these structures for fabrication of ultrahigh aspect ratio microchannels. Usage of a diluted acid mixture of 22% H3PO4 and 24% H2SO4 accelerated the etching process significantly to an etching parameter D of 11.2 μm2/s, which is three times higher than previously reported. Additionally, the selectivity of the etching process was increased by an order of magnitude.