Filament-induced self-written waveguides in glassy As4Ge30S66

The filamentation of femtosecond laser pulses and filament-induced self-writing of a permanent waveguide are observed in As 4 Ge 30 S 66 chalcogenide glass. The radial profile of the self-written waveguide is extracted from the defocused transmission microscopic images via a two-step procedure: at first the phase image of the waveguide is computed using the transport-of-intensity equation and then the index profile is obtained from the phase image by applying the inversed Abel transform.