Fig. 1. Measured relative intensity of reflected light from the prism versus the effective refractive index at a wavelength of 633 nm before and after annealing for O implanted planar waveguides: (a) TM polarized light and (c) TE polarized light. Effective refractive indices of the (b) TM₀ mode and (d) TE₀ mode varying with different annealing temperatures for the same time of 30 min.

Fig. 2. Dpa profile of the 3 MeV O ions with the fluence of 1.5 × 10¹⁵ ions/cm² implanted into LiNbO₃ crystal.

Fig. 3. Reconstructed RIP of the LiNbO₃ planar waveguide at a wavelength of 633 nm after A1 annealing treatment: (a) TE; (b) TM.

Fig. 4. Near-field intensity profiles of the LiNbO₃ planar waveguide at a wavelength of 633 nm after A2 annealing treatment: (a) measured by the end-face coupling method; (b) calculated by the beam propagation method.

Fig. 5. Optical microscope images of ridge waveguide cross section: (a) WG15; (b) WG25; (c) WG35; (d) WG50.

Fig. 6. Near-field intensity profiles of the LiNbO₃ ridge waveguide with a width of 15 µm at the wavelength of 633 nm: (a) measured by the end-face coupling method; (b) calculated by the beam propagation method.