Planar waveguide in beta barium borate formed by proton implantation and optical properties in visible and near-infrared band

Abstract β-BaB 2 O 4 is nonlinear crystal that provides attractive features for various nonlinear optical application. We report on z -cut β-BaB 2 O 4 planar waveguide produced by multi-energy proton implantation in total of 3 × 10 16 ion/cm 2 at room temperature. The refractive index profile is a barrier-confined distribution, which is reconstructed according to the dark mode spectroscopy at the wavelength of 633 nm. The near-field light intensity profiles in the visible (633 nm) and near-infrared band are measured by end-face coupling method. The absorption spectra recorded over the wavelength range 185–2500 nm shows there is hardly change after proton implantation. The investigation results of the Raman spectra demonstrate that the positions and widths of all the peaks are very similar in the β-BaB 2 O 4 crystal and waveguide layer.