Layout for polarization insensitive modulation in LiNbO₃ waveguides

We present in this paper a new waveguide-electrode layout for electrooptical devices integrated in a Z-cut X-propagating lithium niobate crystal. Polarization independent operation is achieved in this structure by a combination of several factors: simultaneous utilization of three electrooptic coefficients (r₃₃ r₃₁ r₂₂), electrode shift with respect to waveguides, and consideration of a necessary insertion of a buffer layer. Phase and amplitude modulation schemes are described based on this configuration. The layout has advantages, when compared to other polarization-insensitive schemes, in terms of lower voltage length and absence of polarization conversion.