We report on a new wet etching/ion implantation method for fabricating ridge waveguide on <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> -cut LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> . The ridge structures are produced on LiNbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> crystal by anisotropic wet etching via minus <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> face. Mode guiding at wavelength of 632.8 nm has been realized by using direct 4.5 MeV oxygen implantation without any implantation mask. The ridge waveguide shows a reduced propagation loss of 1.3 dB/cm after the thermal annealing process.
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