Improved 2 µm broadband luminescence in Tm 3+ /Ho 3+ doping tellurite glass

Abstract

Tm 3+ /Ho 3+ doping tellurite glasses (TeO 2 -ZnO-La 2 O 3 ) were prepared by applying melt-quenching technique, and the ∼2.0 µm band luminescence characteristics were examined. A broadband and relatively flat luminescence at 1600 to 2200 nm was observed in the tellurite glass co-doped by 1.0 mol% Tm 2 O 3 and 0.085 mol% Ho 2 O 3 under the excitation of 808 nm laser diode (LD), which is the result of spectral overlapping of 1.83 µm band of Tm 3+ ions and 2.0 µm band of Ho 3+ ions. Further, about 103% enhancement was acquired after the introduction of 0.1 mol% CeO 2 and 7.5 mol% WO 3 at the same time, which is primarily caused by the cross-relaxation between Tm 3+ and Ce 3+ ions together with the enhanced energy transfer from the Tm 3+ : 3 F 4 level to Ho 3+ : 5 I 7 level due to the increase in phonon energy. Spectral characteristics associated with the radiative transition of Ho 3+ and Tm 3+ ions on the basis of Judd-Ofelt theory, and the fluorescence decay behaviors after the addition of Ce 3+ ions and WO 3 component were analyzed to understand the broadband and luminescence enhancement. The findings in this work indicate that tellurite glass with optimal Tm 3+ -Ho 3+ -Ce 3+ tri-doping combination and appropriate amount of WO 3 is a prospective candidate for broadband optoelectronic devices operated in the infrared bands.