Photoluminescence at 1.54 μm in sol-gel-derived, Er-doped BaTiO₃ films

Nanostructured Er-doped BaTiO₃ films were deposited by the sol-gel method on SiO₂/Si substrates. The spontaneous luminescence in the films at 1.54 μm was observed under the excitation of both 514 and 980 nm lasers. Transient photoluminescence showed that, for the Er:BaTiO₃ film containing 3.0 mol% Er, the decay of the 1.54 μm emission is a single exponential decay with a 1/e lifetime of approximately 5 ms. Concentration quenching was observed for the film containing 5.0 mol% Er, which was attributed to energy transfer and cross relaxation between closely sited Er³⁺ ions in the BaTiO₃ lattice.