Simultaneous three-photon absorption induced ultraviolet upconversion in Pr3+:Y2SiO5 crystal by femtosecond laser irradiation

Near-infrared to ultraviolet upconversion luminescence was observed in the Pr3+:Y2SiO5 crystal with 120 fs, 800 nm infrared laser irradiation. The observed emissions at around 270 nm and 305 nm could be assigned to 5d → 4f transitions of Pr3+ ions. The relationship between the upconversion luminescence intensity and the pump power of the femtosecond laser reveals that the UV emission belongs to simultaneous three-photon absorption induced upconversion luminescence.