6 November 2000 Time-resolved dynamics of plasma self-channeling and bulk modification in silica glasses induced by a high-intensity femtosecond laser
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Proceedings Volume 4088, First International Symposium on Laser Precision Microfabrication; (2000) https://doi.org/10.1117/12.405677
Event: First International Symposium on Laser Precision Microfabrication (LPM2000), 2000, Omiya, Saitama, Japan
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.
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Sung-Hak Cho, Sung-Hak Cho, Hiroshi Kumagai, Hiroshi Kumagai, Katsumi Midorikawa, Katsumi Midorikawa, Minoru Obara, Minoru Obara, } "Time-resolved dynamics of plasma self-channeling and bulk modification in silica glasses induced by a high-intensity femtosecond laser", Proc. SPIE 4088, First International Symposium on Laser Precision Microfabrication, (6 November 2000); doi: 10.1117/12.405677; https://doi.org/10.1117/12.405677
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