Bright up-conversion green photoluminescence in Ho~(3+)-Yb~(3+) co-doped Bi_4Ti_3O_(12) ferroelectric thin films

摘要

Ho~(3+)-Yb~(3+) co-doped bismuth titanate ferroelectric thin films were prepared by a chemical solution deposition method on fused silica substrates and their up-conversion luminescence characteristics excited by a 980 nm diode laser were investigated. The two emission bands centered at 546 and 656 nm in the emission spectra can be assigned to ~5F_4 + ~5S_2 → ~5I_8 and ~5F_5 → ~5I_8 transitions of Ho~(3+) ions, respectively. A bright green emission was observed even when the laser pumping power was relatively low. The dependence of the emission intensity on the pumping power indicated that the up-conversion emission in the thin films was a two-photon process. The up-conversion emission mechanism is discussed in detail. This study suggests that Ho~(3+) and Yb~(3+) co-doped Bi_4Ti_3O_(12) thin films can be applied to the fabrication of new multifunctional photoluminescence ferroelectric thin-film devices.