Upconversion luminescence from Nd ³⁺-doped gerimania-ormosil organic-inorganic hybrid films derived at low temperature

Nd ³⁺-doped germania-ormosil hybrid films are synthesized by a sol-gel spin-coating technique for photonic applications. Acid-catalyzed solutions of γ-glycidoxypropyltrimethoxysilane mixed with gemanium isopropoxide are used as matrix precursors. Planar waveguide films with a thickness of about 1.8-μm are obtained by a single spin-coating process and at low temperature heat treatment. The effects of Nd ³⁺ doping concentration and heat treatment temperature on upconversion emission of the hybrid films are studied. An intense room-temperature violet upconversion emission at 397 nm is observed from the hybrid film with an optimum Nd ³⁺ concentration of 0.5 mol% upon excitation with a yellow light at 584 nm.