Ultra-broadband near-infrared luminescence of Ni²⁺: ZnO-Al ₂O₃-SiO₂ nanocomposite glasses prepared by sol-gel method

We have studied the synthesis and near-infrared luminescent properties of Ni2+-doped ZnO-Al2O3-SiO2 nanocomposite glasses embedded activated spinel nanocrystals prepared using a sol-gel technique. Nanocrystal-dependent optical properties in Ni 2+-doped nanocomposite glasses were systematically investigated. We found that Ni2+ ion is optically active only in the composite embedded nanocrystals, which can provide octahedral position with appropriate crystal field strength. Near-infrared emission ranging from 1100 to 1600 nm was observed in the Ni2+-doped composite fabricated by sol-gel method. Such an ultra-broadband luminescence from the nanocomposite could cover the infrared emission bands obtained from multiple rare earth ions (Ho3+, Pr3+, and Tm3+) doped glasses.