Reverse saturable absorption in nano colloidal Ge28Sb12Se60 chalcogenide glass

► Linear and nonlinear absorption properties of the new nano colloidal solutions of Ge28Sb12Se60 glass was synthesized and investigated. ► The energy gap of the dispersed chalcogenide nanoclusters was found to depend on cluster size which is inversely proportional to concentration. ► Nonlinear optical characterisation of samples studied by the Z-scan technique reveal a strong reverse saturable absorption through two photon absorption. ► The studies show that materials are promising candidates for optoelectronic devices, optical limiters and for the development of nonlinear optical devices with a relatively small limiting threshold.