Selectively enhanced up- and down-conversion emissions of Er3+ via Yb3+-Mn2+ dimer sensitizing in spinel MgGa2O4:Er3+,Yb3+,Mn2+

Selectively enhanced green upconversion (UC) and near-infrared (NIR) downconversion (DC) emissions of Er 3+ by Yb 3+ -Mn 2+ dimer sensitizing have been demonstrated in Er 3+ /Yb 3+ /Mn 2+ tri-doped spinel MgGa 2 O 4 upon excitation of 980   nm laser diode (LD). By optimizing the doping rate of Mn 2+ , the intensity ratio of green to red UC emission intensities of Er 3+ (G/R) could be enhanced about 10 times. Meanwhile, the 1.5   μm NIR DC emission could also be increased about 3.6 times in this system. The DC and UC emission properties, UC mechanism, as well as the enhancing mechanism have been investigated and discussed in detail. A selectively enhancing mechanism based on Yb 3+ -Mn 2+ dimer sensitizing is proposed to explain the selectively enhancing phenomena. This work could inspire the design of novel UC materials for various applications, such as temperature sensors and optical transmission, etc.