Linear and non-linear optical properties of transparent glass-ceramics based on Co2+-doped Zn(Al,Ga)2O4 spinel nanocrystals

Abstract Transparent glass-ceramics containing Co2+:Zn(Al,Ga)2O4 spinel nanocrystals with sizes of 6-11 nm were prepared on the basis of the glass of the ZnO-Al2O3-Ga2O3-SiO2 system nucleated by TiO2. The absorption and luminescence properties of these glass-ceramics are defined mainly by tetrahedrally coordinated Co2+ ions located in Zn(Al,Ga)2O4 nanocrystals with spinel structure. Co2+ ions in glass-ceramics exhibit absorption saturation at 1.54 µm (the 4A2(4F)→4T1(4F) transition of Co2+ ions in tetrahedrally coordinated sites). This absorption band is shifted to higher wavelengths by 20 nm as compared with glass-ceramics with no Ga2O3 addition. The concentration of Co2+ ions in Zn(Al,Ga)2O4 nanocrystals changes in a complex way with rise in heat-treatment temperature. Characteristic times of luminescence decay, values of ground-state absorption cross-sections, and absorption saturation recovery time were determined. The developed glass-ceramics are promising as saturable absorbers for 1.6 µm erbium lasers.