Upconversion properties of Y2O3:Er,Yb nanoparticles prepared by laser ablation in water

► We prepared Y2O3:Er,Yb nanoparticles by laser ablation in liquid, and their upconversion properties were investigated. ► Average particle size was several 10 nm, which increased with the increase in irradiated laser power of preparation. ► Green and red emission was observed by the excitation at 980 nm. ► Number of photon of nanoparticles involved in route was a value among 2 and 3 which indicated the blend of 2 and 3 photon process.