Low-loss ridge Ti:LiNbO₃ waveguides fabrication

In this work we discuss a method of smooth waveguide fabrication by wet etching, using a novel mixture of organic and inorganic acids. We fabricated 4.5μm-deep large single mode waveguide with walls and edges roughness comparable with the roughness of non-etched regions. Surface and wall roughness as well as etching rates and propagation losses are presented and compared to characteristics achieved by traditional wet etching recipes. The method was developed as part of the effort to implement fast and widely tunable AWG-based wavelength filter with channel spacing suitable for dense WDM networks.