Patent ID: 7280712

Claim:
An apparatus, comprising: an optical waveguide having adjoining first and second regions disposed in semiconductor material, the first and second regions having opposite doping types; a first buffer disposed along the optical waveguide; a first higher doped region of semiconductor material outside an optical path of the optical waveguide, an inner portion of the first higher doped region adjoining and coupled to the first region of the optical waveguide, an outer portion of the first higher doped region adjoining the first buffer, the first higher doped region having a higher doping concentration than a doping concentration within the optical path of the optical waveguide; a first contact having an inner portion adjoining and coupled to the first higher doped region, the first contact having an outer portion adjoining the first buffer; and a depletion region overlapped by the optical path of the optical waveguide at an interface between the first and second regions of the waveguide, the first and second regions of the waveguide having respective doping concentrations such that the depletion region is present without a drive voltage externally applied to the optical waveguide.