The invention relates to suppression of high frequency resonance in an electro-optical
device. The electro-optical device includes an optical waveguide formed in a substrate
and a plurality of electrically floating electrode segments that are positioned
on the substrate to intensify an electric field in the optical waveguide. The device
also includes a RF ground electrode that is positioned on the substrate. The RF
ground electrode defines a slot having a shape that suppresses modal conversion
and propagation of high order modes in the RF ground electrode and in the plurality
of electrically floating electrode segments, thereby suppressing modal coupling
to the substrate. The device further includes a buffer layer formed on the upper
surface of the substrate, on the plurality of electrically floating electrode segments,
and in the slot. A driving electrode receives a RF signal that induces-the electric
field in the optical waveguide.
