Infrared-to-violet upconversion from Yb3+ and Er3+ codoped amorphous fluoride film prepared by pulsed laser deposition

Yb 3+ – Er 3+ codoped amorphous Zn0.3Al0.25Pb0.3Li0.09Yb0.1Er0.01F2.37 film has been prepared by pulsed-laser deposition. Violet, green, red, and ultraviolet upconversion emissions were observed under infrared excitation at 988 nm. In comparison with the upconversion of the target, the violet and ultraviolet emissions are enhanced greatly. The enhancement is attributed to the diminishing of the cross relaxation: G11/24→4F9/2 (Er3+): F7/22→2F5/2 (Yb3+) induced by the decrement of the structure parameter Ω2.