Structure and nonlinear optical properties of novel transparent glass-ceramics based on Co2+:ZnO nanocrystals

Transparent glass-ceramics (GCs) based on Co2+:ZnO nanocrystals (mean diameter, 11?nm) are synthesized on the basis of cobalt-doped glasses of the K2O?ZnO?Al2O3?SiO2 system. For these GCs, the absorption band related to the 4A2(4F)?????4T1(4F) transition of Co2+ ions in tetrahedral sites spans until ~1.73 ?m. Saturation of the absorption is demonstrated at 1.54 ?m, with a saturation fluence F s??=??0.8?????0.1 Jcm?2 (? GSA??=??1.7?????0.2??×??10?19 cm2) and a recovery time of 890?????10 ns. Passive Q-switching of an Er,Yb:glass laser is realized with the synthesized GCs. This laser generated 0.37 mJ/100 ns pulses at 1.54 ?m. The developed GCs are promising as saturable absorbers for 1.6?1.7 ?m crystalline erbium lasers.