Zirconium-diffusion-doped Ti:LiNbO_3 strip waveguide for integrated optics

Abstract

We report Zr4+-doped Ti:LiNbO3 strip waveguide fabricated by Zr4+-diffusion-doping followed by diffusion of 8 μm wide, 100 nm thick Ti-strips on a Z-cut congruent substrate. Optical study shows that the waveguide well supports both TE and TM, is single-mode at the 1.5 μm wavelength, and has a loss ≤ 1.3/1.5 dB/cm for the TE/TM mode. Secondary ion mass spectrometry study shows that the Zr4+-profile part having a Zr4+-concentration above the threshold of photorefractive damage covers 60% (70%) ordinary (extraordinary) index profile in the waveguide. We conclude that the waveguide is optical-damage-resistant.