Optical properties of Ge28Ga6.2S65.3:Er0.5 glass: Stark levels and optical gain coefficient

The absorption and emission spectra corresponding to optical transitions between the 4I15/2, 4I13/2 and 4S3/2 manifolds in Er3 + ions in a Ge28Ga6.2S65.3:Er0.5 (a stoichiometrically derived composition) chalcogenide glass have been investigated at temperatures varying from 12 to 293 K. The combined analysis of spectra corresponding to 4I15/2 → 4S3/2, 4S3/2 → 4I15/2 and 4I13/2 → 4I15/2 transitions has allowed us to determine, in a self-consistent way, the energy positions of the Stark levels in the 4I15/2, 4I13/2 and 4S3/2 manifolds. The Stark levels are then used to calculate the emission cross-section and examine its spectral shape, and hence calculate the dependence of spectral optical gain coefficient on the relative population of the 4I15/2 and 4I13/2 manifolds.