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

Successful incorporation 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 ⁴I_13/2 (first excited) and the ⁴I_15/2 (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