Mid-infrared fluorescence properties, structure and energy transfer around 2 µm in Tm3+/Ho3+ co-doped tellurite glass

Abstract

Tm3+/Ho3+ doped tellurite glasses with good thermal stability and low phonon energy are prepared. 1.8µm fluorescence, enhanced near 2µm fluorescence and a weak 2.3µm fluorescence are observed in the Tm3+/Ho3+ co-doped glasses. The energy transfer mechanism between Tm3+ and Ho3+ has been analyzed according to the absorption spectra, the emission spectra and the level structures of Tm3+ and Ho3+ ions. The decay lifetime of 1.8µm and 2µm fluorescence in Tm3+/Ho3+ co-doped tellurite glass are 0.38ms and 2.46ms, respectively. Moreover, the energy transfer efficiency between Tm3+:3F4 and Ho3+:5I7 levels is calculated and compared. Additionally, the calculated forward energy transfer coefficient CTm-Ho is about five times as large as the reverse energy transfer coefficient CHo-Tm. Results demonstrate that the Tm3+/Ho3+ doped tellurite glass has excellent spectroscopic properties and can be an attractive candidate for 2µm laser.