The present invention provides an optical waveguide modulator. In one embodiment, the optical waveguide modulator includes a semiconductor planar optical waveguide core and doped semiconductor connecting paths located adjacent opposite sides of the core and capable of applying a voltage across the core. The optical waveguide core and connecting paths form a structure having back-to-back PN semiconductor junctions. In another embodiment, the optical waveguide modulator includes a semiconductor optical waveguide core including a ridge portion wherein the ridge portion has at least one PN semiconductor junction located therein. The optical waveguide modulator also includes one or more doped semiconductor connecting paths located laterally adjacent the ridge portion and capable of applying a voltage to the ridge portion.