Suppression of high frequency resonance in an electro-optical modulator

A method for suppressing modal coupling to a substrate of an electro-optic device comprising:

• inducing an electric field in an optical waveguide by applying an RF signal to a driving electrode;
• intensifying the electric field in the optical waveguide by positioning a plurality of electrically floating electrode segments and a plurality of electrically grounded electrode segments proximate to the optical waveguide so that each of the plurality of electrically grounded electrode segments are separated from an adjacent one of the plurality of electrically grounded electrode segments by a predetermined distance;
• and
• interrupting continuity of induced electrical current in the plurality of electrically grounded electrode segments, thereby substantially prohibiting modal conversion and propagation of high order modes in the plurality of electrically grounded electrode segments and the plurality of electrically floating electrode segments.

An electro-optic device comprising:

• means for inducing an electric field in an optical waveguide formed in a substrate;
• means for intensifying the electric field in the optical waveguide with a plurality of electrically floating electrode segments and a plurality of electrically grounded electrode segments so that each of the plurality of electrically grounded electrode segments are separated from an adjacent one of the plurality of electrically grounded electrode segments by a predetermined distance;
• and
• means for interrupting continuity of induced electrical current in the electrically grounded electrode segments, thereby substantially prohibiting modal conversion and propagation of high order modes in the plurality of electrically grounded electrode segments and the plurality of electrically floating electrode segments.

An electro-optic modulator comprising:

• a substrate including a first and a second optical waveguide that form an interferometer in an upper surface of the substrate;
• a plurality of electrically floating electrode segments that are positioned on the substrate to intensify an electric field in the first and the second optical waveguides;
• a plurality of electrically grounded electrode segments that are positioned on the substrate so that each of the plurality of electrically grounded electrode segments are separated from an adjacent one of the plurality of electrically grounded electrode segments by a predetermined distance, the plurality of electrically grounded electrode segments substantially prohibiting modal conversion and propagation of high order modes in the plurality of electrically grounded electrode segments and the plurality of electrically floating electrode segments, thereby suppressing modal coupling to the substrate;
• a buffer layer formed on the substrate, the plurality of electrically floating electrode segments, and the plurality of electrically grounded electrode segments;
• and
• a driving electrode that is formed on the buffer layer, the driving electrode adapted to receive an RF signal from an RF input, the RF signal inducing the electric field in the first and the second optical waveguides.