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Proceedings Paper

Laser micromachining of transparent fused silica with 1-ps pulses and pulse trains
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Paper Abstract

Ablation rates and etched-surface morphology of fused silica has been studied with 1-ps Nd:glass laser pulses in a regime of near-diffraction-limited spot size. Shallow holes of 1.7- micrometers diameter were too small for the formation of laser- induced periodic-surface structures. Atomic-force and scanning-electron microscopy showed that reproducible etch depth and moderately smooth surfaces are attainable for low fluences of 5.5 - 45 J/cm2--the `gentle' ablation regime. Etch depth progressed linearly with the number of laser pulses until the onset of surface swelling and shock- induced microcracks after a critical number Nc of laser pulses, scaling as Nc equals 1.7 + 80/F (fluence F in J/cm2). Below this limit--for accumulated etch depths less than approximately 2 micrometers --3D surface structuring with sub-micron precision is possible with picosecond-laser pulses. In the strong ablation regime (F > 45 J/cm2), surface morphology was poor and microcracking developed within 2 - 4 pulses. These shock-induced microcracking effects were eliminated when a mode-locked train of approximately 400 identical 1-ps pulses, each separated by 7.5 ns, was applied. Very smooth and deep (approximately 30- micrometers ) holes of 7 - 10-micrometers diameter were excised at a total fluence of approximately 100 kJ/cm2, establishing a new means for rapid and precise micromachining of fused silica and other brittle materials.

Paper Details

Date Published: 4 June 1999
PDF: 8 pages
Proc. SPIE 3616, Commercial and Biomedical Applications of Ultrafast Lasers, (4 June 1999); doi: 10.1117/12.351828
Show Author Affiliations
Peter R. Herman, Univ. of Toronto and Photonics Research Ontario (Canada)
Anton Oettl, Univ. of Toronto and Photonics Research Ontario (Canada)
Kevin P. Chen, Univ. of Toronto and Photonics Research Ontario (Canada)
Robin S. Marjoribanks, Univ. of Toronto and Photonics Research Ontario (Canada)

Published in SPIE Proceedings Vol. 3616:
Commercial and Biomedical Applications of Ultrafast Lasers
Murray K. Reed; Joseph Neev, Editor(s)

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