Study of damage in fused silica induced by ultra-short IR laser pulses

We report on a neu type of permanent damage obtained in bulk fused silica by focusing IR femtosecond laser pulses with microjoule energy. It consists of an uniaxial birefringence zone over a lateral size of a few microns and a depth of a few tens of microns. The birefringence zone is followed by sub-micrometer filamentary cracks extending up to 80 mum. Nonlinear pulse propagation plays a crucial role in the onset of this type of damage. (C) 2001 Elsevier Science B.V. All rights reserved.