Detailed index profiles of ion implanted waveguides in KNbO₃

Abstract

Abstract Planar optical waveguides have been produced in KNbO3, by He ion implantation at 2.0 MeV. The depth profiles for the two indices (na and nc) have been determined using a dark mode reflectivity calculation. They show a pronounced anisotropic behaviour. For a dose of 2 × 1016 cm−2 the nuclear damage peak has an index decrease ∼10% for na, and ∼7% for nc, showing a sensitivity to nuclear damage at least three times that of LiNbO3. The electronic damage region has ∼0.5% decrease for na, but an increase for nc which is larger at shorter wavelengths. This anisotropic and dispersive behaviour is comparable with other implanted niobates, and a similar damage mechanism of radiation-enhanced diffusion is suggested.