Optical Waveguide Formation in LiNbO₃ by the 2.6 MeVNickel Ions Implantation

The optical waveguide was formed on an LiNbO₃ substrate by 2.6 MeV nickel ions implantation to the dose of 9 x 10¹⁴ ions/cm². Five dark modes were observed by the prism coupling technique. The refractive index profile was obtained by using the reflectivity calculation method. A large index decrease was found in the guiding region and in the optical barrier, which is somewhat different from that of the LiNbO₃ waveguide formed by the MeV He⁺ ions. The position of the optical barrier is deeper than that of the damage peak calculated by TRIM'90 (Transport of Ions in Matter) code. The crystal lattice damage in the guiding region caused by the Ni⁺ ion implantation was analysed by the Rutherford backscattering/channelling technique.