Optical transitions and upconversion properties of Er3+-doped chloride tellurite glasses

Er3+-doped lead chloride tellurite glasses were prepared using the conventional melting and quenching method. The absorption spectra were measured and the Judd-Ofelt analysis was performed. The spectroscopic parameters such as the intensity parameters, transition probabilities, radiative lifetimes, and branching ratios were obtained. Intense infrared emission and visible upconversion luminescence under 976nm excitation were observed. For the 1.55 mum emission, the full width at half maximum and the emission cross sections are more than 50nm and 8 x 10(-20) cm(2), respectively. Three efficient visible luminescences centred at 525, 547, and 658nm are assigned to the transitions from the excited states H-2(11/2), S-4(3/2), and F-4(9/2) to the ground state I-4(15/2), respectively. The upconversion mechanisms and the power-dependent intensities are also discussed and evaluated.