Near vacuum ultraviolet luminescence of Gd3+ and Er3+ ions generated by super saturation upconversion processes

Abstract

Near vacuum ultraviolet (UV) upconversion (UC) emissions with a spectral resolution of 1 nm, from the 6GJ, 6D J, 6IJ, 6PJ levels of Gd3+ and the 2L17/2, 4D 7/2, 2H(2)9/2, 2D5/2, 4G7/2, 2K13/2, 2P 3/2 levels of Er3+, were observed under 974 nm laser excitation. Mechanism analyses illustrate that successive energy transfers (ETs) from Yb3+ to Er3+ generate UV UC radiations in Er 3+, while two resonant ETs from Er3+ to Gd3+ lead to UV UC radiations in Gd3+. Power dependence analyses indicate that the expected inefficient four- and five-photon processes have been switched into efficient two-photon processes due to a super saturation UC phenomenon that employs consecutive saturations at the intermediate states. ©2009 Optical Society of America.