An electro-optic modulator that is disposed along a surface of a substrate includes an optical waveguide having an optical waveguide core disposed along the surface, and two electrode stacks, each of the stacks extending along a corresponding side of a segment of the optical waveguide core to modulate light therein. Each stack includes two electrode segments vertically stacked over the surface of the substrate; wherein at least a part of the segment of the optical waveguide core along the surface is vertically located between the electrode segments of each electrode stack.