Microchannel formation through Foturan® with infrared femtosecond and ultraviolet nanosecond lasers

Abstract

Formation of microchannels produced through 1 mm thick photostructurable glass (Foturan®) samples with two different lasers, an IR laser that gives 450 fs pulses at 1027 nm wavelength and an UV laser delivering 10 ns pulses at 355 nm wavelength, has been studied. After laser irradiation, the samples were submitted to thermal treatment and selective etching with hydrofluoric acid (HF) for microchannel formation. Two different acid concentrations (5% and 10%) were tested. It has been found that photoexcitation with the femtosecond laser can be related to a multiphoton absorption process requiring eight photons, and the critical dose of radiation for this process to occur has been determined. Etch rates with 10% HF are about two times higher than with 5% HF under equal irradiation conditions, while similar etch contrast ratios are attained. High etch rate ratios, together with small modified areas, have been found to play a determinant role in obtaining microchannels with the best aspect ratios. Use of the femtosecond laser in the IR allows the modification of smaller zones, but to the detriment of high etch rates.