Spatially resolved Raman analysis of laser induced refractive index variation in chalcogenide glass
Résumé
We report a detailed 2D μ-Raman analysis of the refractive index modification (Δn) induced by femtosecond laser filament in the bulk of Ge-Ga-S ternary chalcogenide glass. The invariant illumination and detection geometry during the 2D scanning, allows both qualitative and quantitative determination of the proportion of different structural units to be carried out. The results indicate that during the light-matter interaction, S3Ga-GaS3 ethane like groups are transformed into triclusters of Ga/S. The decreased population of edge- and corner-sharing GeS4/2 tetrahedra implies the formation of mixed triclusters : T/S where T = Ga and/or Ge. Finally, correlations between photostructural changes and Δn are presented.