Birefringent modifications induced by femtosecond filaments in optical glass

摘要

We present a study of the refractive index modifications spontaneously induced by infrared femtosecond filaments propagating in the bulk of transparent solids. It was found that extended modified refractive index channels up to several mm in length can be formed under loose focusing conditions in fused silica. The observed birefringence zone at the beginning of these channels is attributed to the anisotropic stress induced via nonlinear losses in the high intensity region of the filament.