Sensitisation of erbium luminescence in erbium-implanted alumina

Experimental evidence of an efficient broadband sensitisation mechanism in erbium-implanted alumina is presented. Alumina thin films were deposited by plasma-enhanced chemical vapour deposition. The as-grown films were implanted with erbium. Photoluminescence excitation spectra showed that erbium-implanted alumina thin films exhibit 1.53 μm luminescence even when pumped at wavelengths outside Er3+ absorption bands. The samples were analysed structurally using transmission electron microscopy and electron energy loss spectroscopy. We postulate that the sensitising species is either small nanoclusters of aluminium or pairs of aluminium ions, though the possibility of defect-mediated sensitisation cannot be conclusively ruled out at this stage.