Laser-induced birefringence in optical glasses

Laser-induced birefringence in silicate glasses is investigated. The birefringence is found at the boundary between the irradiated and unirradiated regions in the glass after long-term exposure to N₂ laser radiation (λ = 337 nm). Along with the stationary effect, a temporal (transient) change in the polarization of the probe beam is also observed, which arises only during UV irradiation and vanishes when the irradiation is over. The birefringence found is explained by the occurrence of anisotropy at the boundary between the irradiated and unirradiated regions of a glass due to a local change in the glass density in the irradiated region.