Abstract

We tightly focus femtosecond laser pulses in the bulk of a transparent material. The high intensity at the focus causes nonlinear absorption of the laser energy, producing a microscopic plasma and damaging the material. In previous work, we examined the morphology of such material damage^1,2 and measured the dynamics of the plasma expansion.³ Here we report the thresholds for bulk damage and critical self-focusing in fused silica using 110-fs pulses at both 400-nm and 800-nm wavelength. We find that permanent damage can be produced with energies of only tens of nanojoules. In addition, we observe no significant self-focusing at these energies.

© 1999 Optical Society of America