Influence of diluted acid mixtures on selective etching of MHz- and kHz-fs-laser inscribed structures in YAG

We show that the inscription velocity of fs-laser written structures in YAG crystals can be significantly improved by the use of MHz repetition rates for the writing process. Using a 10 MHz inscription laser, record high writing velocities up to 100 mm/s are achieved. Also, the selective etching process is accelerated using a diluted mixture of 22% H3PO4 and 24% H2SO4. The diluted mixture enables selective etching of up to 9.6 mm long, 1 mu m wide and 18 mu m high microchannels in 23 days. The etching parameter D of 11.2 mu m(2)/s is a factor of 3 higher than previously reported and the selectivity is even increased by an order of magnitude. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

It is shown that utilizing MHz repetition rates for fs-laser written structures in YAG crystals and a diluted mixture of H3PO4 and H2SO4 can significantly improve inscription velocity and selective etching efficiency. This approach achieves record high writing velocities and increased selectivity, providing a more efficient and precise microchannel fabrication process.