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Proceedings Paper

Time-resolved dynamics of plasma self-channeling and bulk modification in silica glasses induced by a high-intensity femtosecond laser
Author(s): Sung-Hak Cho; Hiroshi Kumagai; Katsumi Midorikawa; Minoru Obara
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Paper Abstract

The time-resolved dynamics of plasma self-channeling and refractive index bulk modification in the silica glasses are first observed using a high-intensity femtosecond (110 fs) Ti: sapphire laser ((Lambda) pequals790 nm) We propose the new pump-probe measurement to observe the lifetime of both plasma self-channeling and induced refractive index bulk modification. The energy variation of transmitted probe beam, which propagates transversely through the plasma self- channeling is measured. At the pre-breakdown domain, the lifetime of induced plasma self-channeling is 20 ps and structural transition time for reforming the refractive index change is 10 ps. At the breakdown domain, however, the lifetime of induced plasma formation is 30 ps and structural transition time for forming the optical damage is 40 ps. We find that the process of refractive index bulk modification is significantly different from those of optical damage. We also measure a wavelength shift (blueshift) of reflected probe beam from the surface of the plasma self-channeling induced by the pump beam. A maximum value of blue wavelength shift is 3 nm when the time delay of probe beam is 2 ps. The expanding velocity of the plasma ionization is calculated from the wavelength shirt (blueshift) using the Doppler formula. A maximum velocity of the plasma ionization is calculated to be approximately 6x105 m/s at the delay time of 2 ps.

Paper Details

Date Published: 6 November 2000
PDF: 4 pages
Proc. SPIE 4088, First International Symposium on Laser Precision Microfabrication, (6 November 2000); doi: 10.1117/12.405677
Show Author Affiliations
Sung-Hak Cho, RIKEN--The Institute of Physical and Chemical Research (Japan)
Hiroshi Kumagai, RIKEN--The Institute of Physical and Chemical Research (Japan)
Katsumi Midorikawa, RIKEN--The Institute of Physical and Chemical Research (Japan)
Minoru Obara, Keio Univ. (Japan)


Published in SPIE Proceedings Vol. 4088:
First International Symposium on Laser Precision Microfabrication
Isamu Miyamoto; Koji Sugioka; Thomas W. Sigmon, Editor(s)

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