Enhanced optical activation of Er3+ in Er3+-doped Al2O3 powders by Y3+ codoping in a sol–gel method

Enhanced photoluminescence (PL) mechanism of Er3+-doped Al2O3 powders by Y3+ codoping at wavelength 1.53 μm has been investigated through PL measurements of 0.1 mol% Er3+- and 0–20 mol% Y3+-codoped Al2O3 powders prepared at a sintering temperature of 900 °C in a non-aqueous sol–gel method. PL intensity and lifetime of Er3+–Y3+-codoped Al2O3 powders composed of γ-(Al,Er,Y)2O3 and θ-(Al,Er,Y)2O3 phases increased with increasing Y3+-codoping concentration. The 10–20 mol% Y3+ codoping in 0.1 mol% Er3+-doped Al2O3 powders intensified the PL intensity by about 20 times, with a PL lifetime prolonged from 3.5 to 5.8 ms. A maximal increase of the optical activity of Er3+ in 0.1 mol% Er3+–Y3+-codoped Al2O3 powders about one order was achieved by 10–20 mol% Y3+ codoping. It is found that the improved PL properties for Er3+–Y3+-codoped Al2O3 powders are mainly attributed to enhanced optical activation of Er3+ in the Al2O3 by Y3+ codoping, and to the slightly increased radiative quantum efficiency of Er3+ in the Al2O3.