Photoluminescence characterisation of Er3+/Yb3+ co-implanted alumina (Al2O3) thin films and sapphire crystals

Successful incorporation of both erbium and ytterbium in alumina by ion implantation is reported. Some evidence for indirect pumping of erbium through the transfer of energy from ytterbium has been observed. Both plasma-enhanced CVD deposited alumina thin films and sapphire crystals were employed as substrates. Yb3+ and Er3+ concentrations ranged from 2.4 At% to 8 At% and from 0.4 At% to 0.8 At%, respectively. The samples show strong, broad, room-temperature photoluminescence at λ = 1.53 µm corresponding to the intra-4f transitions between the 4I13/2 (first excited) and the 4I15/2 (ground) state of Er3+. The full width at half maximum of the emission spectrum is as high as 67 nm for the Al2O3 thin films; for the sapphire crystals it is 45 nm. The fluorescence lifetime of the samples has been measured to be as high as 4.2 ms at 50 mW pump power.