1.55 μm emission and upconversion luminescence of Er3+-doped strontium borate glasses

Er3+-doped strontium borate glasses 10SrCO3–2SrF2–3Li2CO3–85H3BO3:xEr3+ (x=0.5, 1.0, 2.0 and 3.0) were synthesized via conventional melt quenching technique. The emission spectra, the luminescence decay curves and upconversion emission spectra were measured. Under the excitation of a 980 nm laser diode, 1.55 μm infrared fluorescence and efficient green and red upconversion fluorescence have been observed. The broad and intense emission positions centered at around 1550 nm show increasing red shift with the increase of Er3+ ions concentration. It can be noted that the full-width at half-maximum and the decay lifetimes of the 1.55 μm emission show the dependence of Er3+ ions concentration. A possible mechanism has also been proposed. It is worth noting that both the excited state absorption and the energy transfer of Er3+ ions are of great importance to the upconversion process.