Visible and near infrared upconversion photoluminescence from Y2O3:Er3+, Yb3+, Li+ phosphors under 1532Â nm excitation light

Visible and near-infrared upconversion luminescence from Y2O3 co-doped with Er3+, Yb3+ and Li+ phosphors under continuous excitation with 1532 nm light are reported. The upconversion emissions at 530-570 nm (green light emission region), and 640-700 nm (red light emission region) correspond to transitions from the 4S3/2to4I15/2and (4F9/2 + 4I9/2) to 4I15/2 electronic energy levels of the Er3+ ions respectively. The near infrared emissions at 900-1100 nm region correspond to inter-electronic energy levels transitions from 4I11/2 to 4I15/2 of Er3+ ions and 2F5/2 to 2F7/2 of Yb3+ ions. The role of Li+ and Yb3+ ions were to enhance the luminescence emission of these phosphors around 9, 7 and 11 times, respectively in comparison with only-erbium doped samples. The luminescence spectra of these phosphors remain unchanged when dispersed in deionized water, cholesterol and in bovine serum.