Ultraviolet upconversion luminescence in Er3+-doped Y2O3 excited by 532 nm CW compact solid-state laser

Ultraviolet upconversion emissions at 262, 276, 308 and 320 nm were observed from Er3+-doped Y2O3 with a 532 nm continuous wave compact solid-state laser excitation. Power-dependence analysis demonstrates that two-photon upconversion process populates the 4D5/2, 2H9/2 and 2P3/2 states. The energy transfer upconversion (ETU) plays an important role in populating 4D5/2 and 2P3/2 states. It appears that 2P3/2 state population originates from ETU 2H11/2+2H11/2→4I13/2+2P3/2, moreover, a subsequent excited state absorption (ESA) from the 4I9/2 level.