Infrared-to-green and blue upconversion in Tm3+-doped TeO2–PbO glass

The infrared-to-visible upconversion (UC) in Tm3+-doped TeO2–PbO glass was investigated by exciting the samples with a Q-switched neodymium doped yttrium aluminum garnet laser operating at 1064nm. UC emission bands at ∼454, ∼482, and ∼518nm corresponding, respectively, to the transitions D21→F43, G41→H63, and D21→H53 were observed. Based on the dependence of the UC signals as a function of the Tm3+ concentration and excitation intensity, we concluded that the generation of the UC emissions involves excited state absorption and cross relaxation among Tm3+ ions.