Design and preparation of white light emission from up-conversion transitions in Er3+/Tm3+/Yb3+ co-doped cubic zirconia single crystals

High-quality cubic YSZ crystals were designed with various contents of Er 3+ , Tm 3+ and Yb 3+ to produce white light emission, and grown by the optical floating zone method. The up-conversion luminescence spectra of the crystals under 980 nm laser irradiation show three distinct groups of emission peaks at ∼473 nm (blue) generated by the Tm 3+ 1 G 4 → 3 H 6 transition, 531 and 547 nm (green) from the Er 3+ 2 H 11/2  →  4 I 15/2 and 4 S 3/2  →  4 I 15/2 transitions, and 640 and 662 nm (red) from the Er 3+ 4 F 9/2  →  4 I 15/2 transition. The optical power curve obtained by plotting the up-conversion luminescence intensity against the laser power shows that the blue emission involves a three-photon process, whilst both the green and red emissions are the results of two-photon processes. Overall white light emission was observed with the crystal prepared with 0.05 mol% Er 2 O 3 , 0.5 mol% Tm 2 O 3 and 2.0 mol% Yb 2 O 3 , and this crystal is suitable for use in highly efficient white light emission devices.