Up-conversion luminescence from Nd3+ ions doped in NaBi(WO4)2 single crystal

The luminescence of Nd3+-doped in NaBi(WO4)2 single crystal was investigated from 10 K to room temperature. The excitation source was a pulsed dye laser in resonance into the (4G5/2+2G(1)7/2) levels of Nd3+ ions. Several blue emission bands in the up-conversion luminescence spectra corresponded to transitions from 2P1/2 to 4I9/2. Some violet bands corresponding to transitions of 4D3/2 → (4I9/2, 4I11/2, 4I13/2) were also observed. For comparison, the luminescence spectra and decay curves excited by the pulsed 355 nm laser were measured. In order to investigate up-conversion mechanisms, the decay behavior and the dependence of the up-conversion luminescence on laser powers were investigated. The temporal decay behavior of the up-conversion luminescence indicated that the two-photon excited state absorption of the Nd3+ ions was the dominant mechanism in this crystal.