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Title

Time resolved study of femtosecond microfabrication in silica glass

Author(s)

Misawa, Hiroaki;  Juodkazis, Saulius;  Marcinkeviaius, Andrius;  Watanabe, Mitsuru;  Mizeikis, Vygantas;  Matsuo, Shigeki

Abstract

We report investigation of light-induced damage threshold (LIDT) in purified silica (transmission band down to 160 nm) by 350 fs laser pulses at the wavelength of 795 nm and 498 nm. Focusing a single pulse by a high numeric aperture NA = 1.35 microscope objective lens results in one of the lowest single-shot bulk LIDT values reported so far, 5 J/cm(2), while the surface ablation threshold is 2.5 J/cm(2) with both values being well below the critical self-focusing power in silica. Furthermore, we report the peculiarities of damage by two-pulse irradiation (duration of each pulse is 440 fs), where both pulses have energies at the level of 0.5 x LIDT. Comparison between the experimental data and numeric simulation, which takes into account optical free-carrier generation and relaxation, demonstrates that these processes can explain the measured self-focusing, super-continuum generation, and light-induced damage threshold values. We argue that use of high numeric aperture objective, despite substantial temporal pulse stretching, results in tight focusing which is capable of overcoming the beam self-focusing, and the resulting fabrication quality is comparable to that obtained using shorter pulses.

Publication type

Conference paper

Source

Proceedings of SPIE: Laser Applications in Microelectronic and Optoelectronic Manufacturing VI, San Jose, United States, 22-24 January 2001 / Malcolm C. Gower, Henry Helvajian, Koji Sugioka and Jan J. Dubowski (eds.), Vol. 4274, pp. 98-109

Publication year

2001

Keyword(s)

Laser microfabrication;  Light-induced damage threshold;  Silica

Publisher

SPIE

ISSN

0277-786X (series ISSN)

ISBN

9780819439529, 0819439525

Publisher URL

http://dx.doi.org/10.1117/12.432501

Copyright

Copyright © 2001 Society of Photo-Optical Instrumentation Engineers. This paper was originally published in Proceedings of SPIE (Vol. 4274), and is available from: http://dx.doi.org/10.1117/12.432501. The published version of the paper is reproduced here in accordance with the copyright policy of the publisher. One print or electronic copy may be made for personal use only. Systematic electronic or print reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.

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