Influence of B2O3 on spectroscopic properties of Er3+/Yb3+ co-doped tungsten-tellurite glasses

A series of novel Er3+/Yb3+ co-doped (85 - x) TeO2-15WO(3) - x B2O3 (TWB; x = 2 %, 5 %, 8 % (mole fraction)) glasses were prepared. Influence of B2O3 on the spectroscopic properties of Er3+/Yb3+ co-doped tungsten-tellurite glasses were investigated. It is found that the intensity of 1.5 mu m fluorescence, lifetime of the I-4(13/2) level and upconversion fluorescence all decrease with the increase of B2O3 content. The product of full width at half maximum (FWHM) and stimulated emission cross-section (sigma(peak)(e)) of Er3+ :I-4(13/2) -> I-4(13/2) -> I-4(15/2) transition has an optimum when B2O3 is 5% (mole fraction). The emission spectra of Er3+ : I-4(13/2) -> I-4(15/2) transition was analyzed using peak-fit routine, and an equivalent four-level system was proposed to estimate the stark splitting for the I-4(15/2) and I-4(13/2) levels of Er3+ ions in TWB glasses at room temperature.