Methods of fabricating electro-optical modulators and the resulting electro-optical modulators are described herein. In some embodiments, a method comprises defining a waveguide having a core region, implanting dopants into a contact region of the waveguide, and diffusing the dopants laterally toward the core region. In some embodiments, a method comprises implanting n-type and p-type dopants into respective first and second contact regions of the optical waveguide and annealing the optical waveguide to induce lateral diffusion of the n-type and p-type dopants toward a center of the optical waveguide. In some embodiments, an electro-optical modulator comprises a waveguide comprising a contact region and a core region, and the waveguide has a dopant concentration that decreases from the contact region to the core region according to a super-linear curve. Methods and resulting structures described herein provide desirable electrical resistance and low overlap between dopants and optical signals.