Ultraviolet and violet upconversion luminescence inEr3+-doped yttrium aluminum garnet crystals

Abstract

The ultraviolet and violet upconverted luminescence around 320, 410, and 470 nm in ${\mathrm{Er}}^{3+}$-doped yttrium aluminum garnet has been observed at room temperature with a tunable OPO laser excitation. The upconversion mechanisms upon ${}^{4}{S}_{3/2}$ excitation $(\ensuremath{\approx}545 \mathrm{nm})$ are investigated by means of the decay profiles of upconvered luminescence and excitation spectrum. It appears that, depending on the excited wavelength, the upconverted luminescence is dominantly contributed either by energy-transfer upconversion or by excited-state absorption. The relative intensities of upconverted luminescence are discussed using Judd-Ofelt theory.