Optical spectroscopy and scanning near-field optical microscopy on HE+ irradiated lithium fluoride crystals

He+ ions with an energy of 1.5 -2 MeV and doses ranging from 6 ´ 1013 to 2.5 ´ 1016 ions/cm2 were used to produce primary and aggregate defects in Lithium Fluoride (LiF) crystals. The optical properties of the implanted samples and their dependence on ion dose were studied by means of optical absorption spectroscopy and Scanning Near-field Optical Microscopy (SNOM). The results show the formation, for high doses, of macrodefects such as lithium intrinsic nano-aggregates that could play an important role in the realisation of non-linear optical waveguide