Infrared to visible upconversion luminescence in Er3+/Yb3+ doped titanate glass prepared by containerless processing

Er3+ doped TiO2–La2O3 glasses modified by ZrO2 have been successfully fabricated by the containerless method with incorporated Yb3+ ions as sensitizers. Under the excitation of 980 and 808 nm diode lasers, visible emissions centered at 534, 554 and 674 nm are observed, which are assigned to the Er3+ transitions of 2H11/2→4I15/2, 4S3/2→4I15/2 and 4F9/2→4I15/2, respectively. The emission signals are so strong that they can be observed by naked eyes even at pumping power as low as 20 mW. Measurements of pump-power dependent intensity and time-resolved decay behavior of upconversion luminescence show that two-photon excited state absorption (ESA) and energy transfer (ET) between rare earth ions are the predominant mechanisms for upconversion emissions. Besides, the intensity of upconversion luminescence has been enhanced by increasing the concentration of ZrO2 in these rare earth doped bulk titanate glasses.