Intense 2.85 μm mid-infrared emissions in Yb3+/Ho3+ codoped and Yb3+/Er3+/Ho3+ tridoped TBLL fluorotellurite glasses and their energy transfer mechanism

Abstract

Yb 3+ /Ho 3+ codoped and Yb 3+ /Er 3+ /Ho 3+ tridoped TeO 2 –BaF 2 –LaF 3 –La 2 O 3 (TBLL) fluorotellurite glasses with low OH − absorption (0.026 cm -1 ), high glass transition temperature (434 °C) and low phonon energy (784 cm -1 ) were prepared. Their mid-infrared fluorescence properties and related energy transfer (ET) mechanism were studied under 980 nm excitation. A strong emission at 2.85 μm was realized in Yb 3+ /Ho 3+ codoped tellurite glass, which was attributed to the high-efficiency ET from Yb 3+ ions to Ho 3+ , and the ET efficiency was 91.1%. Further introduction of Er 3+ ions induced stronger 2.85 μm emission, and the ET efficiency was improved to 96.2%, ascribed to the establishment of more ET channels and Er 3+ ions playing the role of ET bridge between Yb 3+ and Ho 3+ ions. These results indicate that the Yb 3+ /Er 3+ /Ho 3+ tridoped tellurite glass could be a hopeful gain medium material for the ∼3 μm fiber laser.