An optical device (100, 200, 250, 300, 350, 500, 600, 650, 700, 800, 850, 1000, 1200), comprising: a first silicon waveguide (205, 505, 605, 1005, 1205, 1405) disposed on a dielectric substrate, the first silicon waveguide comprising a first ridge (240A, 640, 825, 1040) extending in a direction of an optical path; a dielectric layer having a lower surface disposed on an upper surface of the first ridge; a second silicon waveguide (215, 515, 615, 1015, 1415) disposed on an upper surface of the dielectric layer opposite the lower surface of the dielectric layer, the second silicon waveguide comprising a second ridge (240B, 740, 820, 1040) extending in the direction of the optical path, wherein the second ridge at least partially overlaps both the dielectric layer and the first ridge, and wherein the first silicon waveguide is doped a first conductivity type and the second silicon waveguide is doped a second, different conductivity type; a first electrical contact coupled to the first silicon waveguide; and a second electrical contact coupled to the second silicon waveguide, wherein the first electrical contact and a third electrical contact are coupled to the first silicon waveguide, with one of the first electrical contact and the third electrical contact being on a left side of the first silicon waveguide, and the other one of the first electrical contact and the third electrical contact being on a right side of the first silicon waveguide, characterized in that the second electrical contact and a fourth electrical contact are coupled to the second silicon waveguide, with one of the second electrical contact and the fourth electrical contact being on a left side of the second silicon waveguide, and the other one of the second electrical contact and the fourth electrical contact being on a right side of the second silicon waveguide, wherein the optical device is configured to receive a first voltage at the first and third electrical contacts, wherein the optical device is configured to receive a second voltage at the second and fourth electrical contacts, to generate a voltage potential that establishes a charge modulation region. a first silicon waveguide (205, 505, 605, 1005, 1205, 1405) disposed on a dielectric substrate, the first silicon waveguide comprising a first ridge (240A, 640, 825, 1040) extending in a direction of an optical path; a dielectric layer having a lower surface disposed on an upper surface of the first ridge; a second silicon waveguide (215, 515, 615, 1015, 1415) disposed on an upper surface of the dielectric layer opposite the lower surface of the dielectric layer, the second silicon waveguide comprising a second ridge (240B, 740, 820, 1040) extending in the direction of the optical path, wherein the second ridge at least partially overlaps both the dielectric layer and the first ridge, and wherein the first silicon waveguide is doped a first conductivity type and the second silicon waveguide is doped a second, different conductivity type; wherein the second ridge at least partially overlaps both the dielectric layer and the first ridge, and wherein the first silicon waveguide is doped a first conductivity type and the second silicon waveguide is doped a second, different conductivity type; a first electrical contact coupled to the first silicon waveguide; and a second electrical contact coupled to the second silicon waveguide, wherein the first electrical contact and a third electrical contact are coupled to the first silicon waveguide, with one of the first electrical contact and the third electrical contact being on a left side of the first silicon waveguide, and the other one of the first electrical contact and the third electrical contact being on a right side of the first silicon waveguide, characterized in that the second electrical contact and a fourth electrical contact are coupled to the second silicon waveguide, with one of the second electrical contact and the fourth electrical contact being on a left side of the second silicon waveguide, and the other one of the second electrical contact and the fourth electrical contact being on a right side of the second silicon waveguide, wherein the optical device is configured to receive a first voltage at the first and third electrical contacts, wherein the optical device is configured to receive a second voltage at the second and fourth electrical contacts, to generate a voltage potential that establishes a charge modulation region.