Saturable Absorber: Transparent Glass-Ceramics Based on Co 2+ , Ga 2 O 3 -doped ZnO Nanocrystals

A saturable absorber for Er lasers - transparent glass-ceramics with nanosized (6 nm) Co 2+ , Ga 2 O 3 -doped ZnO crystals is developed. It exhibits a broad 4 A 2 ( 4 F) → 4T1(4F) absorption band of Co 2+ ions in tetrahedral sites. At ~1.54 μm, the saturation intensity is 0.7±0.1 J/cm 2 and the laser damage threshold is as high as 25±2 J/cm 2 .