Optical and spectral characterization of Er3+/Yb3+-codoped NAT ceramics

Er3+/Yb3+-codoped aluminum oxide (Al2O3) modified tellurite ceramics have been prepared by high-temperature melting. Judd-Ofelt parameters of Eu3+, which was introduced in 15%Na2O-15%Al2O3-70%TeO2 (NAT) ceramic system as a probe, present a medium asymmetry and covalence environment around rare-earth ions. Efficient 551 nm green and 668 nm red two-photon pumped upconversion fluorescence and strong 1.533 μm infrared radiation were observed and recorded in the Er3+/Yb3+-codoped NAT ceramics under the excitation of ∼980 nm diode lasers. For 1.533 μm near-infrared emission, the maximum stimulated emission cross-section was calculated to be 6.61x10-21 cm2, and the ordinary exhibition referring to tellurite glass system is due to the lowering of refractive index, which is caused by the abundance of Al2O3 composition. Efficient visible upconversion and infrared emissions indicate that Er3+/Yb3+-codoped NAT ceramics are promising substrates in developing color light sources, upconversion display devices, infrared sensors and infrared radiation sources.