A novel approach from infrared to ultraviolet emission enhancement in Yb3+, Er3+:CaF2 nanofilms

Under 978 nm excitation, we explored the infrared-to-ultraviolet upconversion properties in the nanofilms with the nanoparticles of Yb3+, Er3+ codoped calcium fluoride (CaF2:Yb3+, Er3+). The strong enhancement of ultraviolet emission was observed. The result is attributed to the optical performance characteristics of the nanostructure materials. Furthermore, a novel upconversion approach explains well the UV-enhanced emission.