Visible upconversion emission intensities are investigated in Er3+-doped Y2O3 nanocrystals. We also find that the upconversion intensity varies nonlinearly with the excitation power with a threshold of 110 mW, which indicates that the green and red emissions would be photon avalanche upconversion when the excitation power exceeds the threshold.
© 2009 Chinese Optics Letters
Yunxiang Wang, Yunfeng Bai, and Yinglin Song, "Multi-photon upconversion luminescence of Er3+-doped Y2O3 nanocrystals," Chin. Opt. Lett. 7, 524-526 (2009)