Refractive index variations induced by femtosecond laser direct writing in the bulk of As2S3 glass at high repetition rate

This paper deals with the refractive index variation (Δn) induced by femtosecond laser irradiation in the bulk of As2S3 glass in a high repetition rate regime. Extensive measurements of spatially resolved Δn profiles of photowritten channels are reported for various values of the pulse energy. Nearly Gaussian profiles are obtained for energy slightly above the threshold whereas at higher energies the structure of Δn is more complex with a negative core surrounded by a positive ring. A thermal model is applied to reproduce the behaviour of the overall structure diameter.

Graphical abstractTypical 3D image of the phase and Δn profiles at different energy values.Figure optionsDownload full-size imageDownload high-quality image (111 K)Download as PowerPoint slideResearch highlights► We characterize Δn profiles induced by fs laser in bulk of chalcogenide glasses. ► We describe the influence of the fs laser pulse energies on the Δn profiles. ► We evidence the thermal origin of the photowritten modifications.