Spectroscopic properties of Er3+-doped fluorotellurite glasses modified by Nb2O5 and WO3.

We have investigated the spectroscopic properties of Er³⁺-doped fluorotellurite glasses with the basic molar composition 75%TeO₂-10%P₂O₅-10%ZnO-5%PbF₂, modified by replacing 5% TeO2 by a metal oxide, namely WO₃ or Nb₂O₅. The absorption edge of the glasses studied has been described within the Urbach approach, while the absorption and photoluminescence spectra have been analyzed in terms of the standard Judd-Ofelt theory, along with the photoluminescence decay of the ⁴I_13/2 and ⁴S_3/2 levels of the Er³⁺ ion. The absorption and emission spectra of the ⁴I_15/2 ↔ 4I_13/2 infrared transition have been analyzed within the McCumber theory to yield the peak emission cross-section and figure of merit for the amplifier gain. It appears that the fluorotellurite glass containing WO₃ as a modifier is characterized by the largest figure of merit, indicating this matrix as a promising new host for doping with Er³⁺ ions. [ABSTRACT FROM AUTHOR]