Upconversion excitation of Cr3+2E emission in Y3Ga5O12 codoped with Cr3+ and Yb3+

Abstract The 2 E → 4 A 2 emission of Cr 3+ in crystals and glasses is of great importance in science and technology. We report a new excitation mode for this emission in Y 3 Ga 5 O 12 (YGG) codoped with Cr 3+ and Yb 3+ . It is based on an upconversion mechanism using 2 F 5/2 of Yb 3+ as an intermediate state. Excitation in the near-IR at 969.6 nm leads to visible luminescence around 700 nm at low temperature. In YGG:2%Cr 3+ ,1%Yb 3+ at 15 K and for a laser power of 150 mW the efficiency of the process is 5.5%. From its time dependence the upconversion mechanism is found to be dominated by an energy transfer step: Two excited Yb 3+ ions simultaneously transfer their 2 F 5/2 excitation to Cr 3+ .