Optical waveguide with homogeneous refractive index profile in LiNbO3 by double-low-energy Oxygen ion implantation

► The waveguide was formed by 550 keV O ion followed by 250 keV O ion implantation. ► A nearly homogeneous damage layer was formed in the annealed waveguide. ► A homogeneous near-field intensity profile was obtained from the waveguide. ► The estimated propagation loss is about 0.5 dB/cm.