LAUSR

Abstract 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 4S3/2 to 4I15/2 and (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.