Optical and spectroscopic properties of Er3+/Yb3+ co-doped calcium borotellurite glasses

Er3+/Yb3+ co-doped calcium borotellurite glasses were prepared by melt quenching technique, and their optical and spectroscopic properties were investigated as a function of Yb2O3 content. Density, refraction index, optical absorption, luminescence, and radiative lifetime were measured at room temperature. Temperature effect in luminescence and radiative lifetime were also considered. Density, molar volume, and refraction index increased with Yb2O3 content. The optical absorption spectra showed characteristic transitions of Er3+ and Yb3+. The luminescence intensities at 1535 nm increased as a function of Yb3+ content. Radiative lifetime values from I-4(13/5) -> I-4(15/2) transition decreased with the increase of Yb3+ due to a higher probability of non-radiative decay rate. The emission cross-section decreased up to 0.92 mol% Yb3+ and exhibited an increase for the 1.58 mol% Yb3+. The gain cross-section shows a potential application in S, C and L bands of the optical communication window. The emission intensity at 1535 nm decreased with the increase of the temperature from 300 to 420 K. The Er3+/Yb3+ codoped calcium borotellurite glasses presented properties, such as high refraction index and high emission at 1535 nm, which are attractive for applications like optical-fiber amplifiers or other photonic devices.