White upconversion emission in Er3+/Yb3+/Tm3+ codoped LiTaO3 polycrystals

• Er/Yb/Tm:LiTaO3 polycrystals were prepared by solid-state reaction method.
• White emission was observed in Er3+/Yb3+/Tm3+:LiTaO3 polycrystal.
• The structural properties were confirmed by XRD.
• The color coordinates were calculated in Er3+/Yb3+/Tm3+:LiTaO3 polycrystals.

White upconversion emission was observed in Er3+/Yb3+/Tm3+:LiTaO3 polycrystals prepared by solid-state reaction method. The structural properties of Er3+/Yb3+/Tm3+:LiTaO3 polycrystals were confirmed by X-ray diffraction (XRD) patterns. The color coordinate of (0.33, 0.33) in 1 mol% Er3+/20 mol% Yb3+/1 mol% Tm3+:LiTaO3 polycrystal was found to be equal to the standard point of energy white-light. The blue emission was populated via the cooperative sensitization upconversion process, and efficient two-photon green upconversion and one-photon red upconversion emissions were observed. The increased green upconversion emission was attributed to the fast cross relaxation process of 3H4 (Tm) + 4I13/2 (Er) → 3H6 (Tm) + 4S3/2 (Er). The gained excellent optical quality of white upconversion emission suggested that Er3+/Yb3+/Tm3+:LiTaO3 polycrystal will be a potential laser candidate material for the application of the three-dimensional backlighting.

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