Patent ID: 7522783

Claim:
An optical modulator comprising: an input waveguide core having a bottom surface disposed over a substrate at a first height, a top surface above the bottom surface, a left side wall extending from the bottom surface to the top surface, and a right side wall extending from the bottom surface to the to surface and disposed opposite to the left side wall; a first branch waveguide core having a bottom surface disposed over the substrate at a second height, a top surface above the bottom surface, a left side wall extending from the bottom surface to the top surface, a right side wall extending from the bottom surface to the top surface and disposed opposite to the left side wall, a first end portion and a second end portion, the second height being greater than the first height, the first end portion being disposed adjacent to the input waveguide core; a second branch waveguide core having a bottom surface disposed over the substrate substantially at the second height, a top surface above the bottom surface, a left side wall extending from the bottom surface to the top surface, a right side wall extending from the bottom surface to the top surface and disposed opposite to the left side wall, a first end portion and a second end portion, the first end portion being disposed adjacent to the input waveguide core; the input waveguide core and the first and second branch waveguides configured such that there is a lateral separation between the right side wall of the input waveguide core and the left side wall of the first end portion of the first branch waveguide core, and a lateral separation between the left side wall of the input waveguide core and the right side wall of the first end portion of the second branch waveguide core; cladding material disposed adjacent to at least one of the first and second branch waveguide cores; and a first signal-modulation electrode and a second signal-modulation electrode, each electrode being disposed adjacent to one of the first and second branch waveguide cores; wherein at least one of the first and second branch waveguide cores comprises an electro-optic material having a refractive index that varies with an applied electric field; and wherein each of the input waveguide core, first branch waveguide core, and second branch waveguide core has a refractive index that is greater than the refractive index of the cladding layer.