Polarized excimer laser-induced birefringence in silica

We have used linearly polarized 193-nm-excimer laser irradiation to create polarization-induced birefringence in silica. We have observed the polarization-induced birefringence irrespective of whether the sample undergoes net compaction or expansion. The sign of the birefringence is dependent on whether the glass is expanding or compacting. It is suggested that the birefringence derives from an anisotropic density change effected by the linearly polarized exposure. This effect can be expressed formally as an optical frequency-induced dc electrostriction.