Abstract: An electro-optical directional coupler is provided having a substrate and a first and second optical waveguide formed on the substrate, where the second waveguide extends adjacent to and parallel with the first waveguide for at least one interaction length. The interaction length has a first end and a second end such that an optical signal applied only to one of the first and second waveguides couples to the other of the first and second waveguides between the ends. A first electrode is proximate the first and second waveguides and between the ends of the interaction length. A first voltage applied to the first electrode independently tunes a coupling of a TE mode. A second electrode located proximate the first and second waveguides and the first electrode and between the ends of the interaction length. A second voltage applied to the second electrode independently tunes a coupling of a TM mode.