The dynamics of absorption after excitation of fused silica and BK7 glass with femtosecond laser radiation are visualized by transient absorption spectroscopy. Focusing laser radiation with pulse durations in the picosecond time regime in BK7 glass generates free electrons with relaxation by emission of radiation or by formation of defects. The temporal and spatial emission characteristics are observed by high-speed photography in the streak mode. The beam waist moves within the pulse duration towards the incoming laser radiation by self-focusing and with the laser radiation absorbed by multi-photon processes. The dynamics of the long lasting stress formation is visualized by time-resolved Nomarski-Photography. The modification of the glass is investigated during and after irradiation with ultra-short pulsed laser radiation (100 fs<tp<3 ps) at the wavelength λ=810 nm. The formation of a sound wave in fused silica and BK7 glass is observed and the mechanical stress, depending on the excitation pulse duration, is measured.
[1]
Pierre Meynadier,et al.
Time-resolved study of laser-induced colour centres in ?
,
1996
.
[2]
J. Marburger,et al.
Self-focusing: theory
,
1975,
International Quantum Electronics Conference, 2005..
[3]
G. Petite,et al.
Ultrafast processes in laser irradiated wide bandgap insulators
,
1997
.
[4]
G. Petite,et al.
Femtosecond multiphoton generation of the self‐trapped exciton in α‐SiO2
,
1992
.
[5]
R. Alfano,et al.
Observation of Self-Phase Modulation and Small-Scale Filaments in Crystals and Glasses
,
1970
.
[6]
P. Meynadier,et al.
Subpicosecond study of carrier trapping dynamics in wide-band-gap crystals
,
1997
.
[7]
Greene,et al.
Primary relaxation processes at the band edge of SiO2.
,
1993,
Physical review letters.