Evidence by Mueller spectropolarimetry of optical rotation imprinted by femtosecond laser in silica

Transmission Mueller-matrix spectroscopy is applied to study femtosecond laser induced modifications in silica glass in the spectral range 450–1000 nm. Within type II regime, the modifications exhibit not only linear birefringence but also circular birefringence. We reveal that the laser polarization orientation determines the amplitude and the sign of the circular properties.