Filamentation and damage in fused silica induced by tightly focused femtosecond laser pulses
- Centre de Physique Theorique, Ecole Polytechnique, CNRS UMR 7644, F-91128, Palaiseau Cedex (France)
- Laboratoire d'Optique Appliquee, Ecole Nationale Superieure des Techniques Avancees-Ecole Polytechnique, CNRS UMR 7639, F-91761 Palaiseau Cedex (France)
We investigate experimentally and numerically the damage tracks induced by tightly focused (NA=0.5) infrared femtosecond laser pulses in the bulk of a fused silica sample. Two types of irreversible damage are observed. The first damage corresponds to a permanent change of refractive index without structural modifications (type I). It appears for input pulse energies beyond 0.1 {mu}J. It takes the form of a narrow track extending over more than 100 {mu}m at higher input powers. It is attributed to a change of the polarizability of the medium, following a filamentary propagation which generates an electron-hole plasma through optical field ionization. A second type of damage occurs for input pulse energies beyond 0.3 {mu}J (type II). It takes the form of a pear-shaped structural damage associated with an electron-ion plasma triggered by avalanche. The temporal evolution of plasma absorption is studied by pump-probe experiments. For type I damage, a fast electron-hole recombination is observed. Type II damage is linked with a longer absorption.
- OSTI ID:
- 20666276
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 71, Issue 12; Other Information: DOI: 10.1103/PhysRevB.71.125435; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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