Transparent glass-ceramics containing Co2+:Zn(Al,Ga)2O4 spinel nanocrystals with sizes of 6–11 nm were studied. Absorption band of the Co2+ ions in the material is shifted to longer wavelengths as compared with glass-ceramics with no Ga2O3 addition. Absorption saturation at 1.54 μm was observed and its characteristics (absorption recovery time, ground-state and excited-state ...