Strip waveguides in LiNbO<inf>3</inf>fabricated by combined metal diffusion and ion implantation

Abstract

Embedded strip waveguides in LiNbO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> are fabricated by a titanium in-diffusion followed by a masked implantation of helium ions which reduces the refractive index in the unmasked regions and confines the optical wave. This technique yields waveguides with well-defined lateral dimensions and strong optical confinement. The index profiles of helium implanted LiNbO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> are determined with an index reduction of more than 1 percent up to about 1 μm depth for 350 keV He+ ions at a dose <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Phi \simeq 10^{16}</tex> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> . Electrooptic devices with self-aligned electrodes are fabricated by using the implantation mask as a lift-off mask, and Mach-Zehndet type interferometers are investigated.