Modification of LiNbO3 optical properties by He+ implantation

Ion beam modified layer on x- and z-cuts of LiNbO 3 single crystal has been produced by 100 keV He ions implantation with doses from 1.10 16 to 1.10 17 at/cm -2 . Using ellipsometry, the complex refractive index [n-i.(lambda) .k/(4(pi) )] was measured for ordinary and extraordinary rays. The effect of ion beam modification depends on the ion beam orientation with respect to the crystal axes. Bombarding along the z-axis conserves the optical anisotropy of the material, both of the refractive index and the absorption coefficient.