An electro-optic device may include a photonic chip having an optical grating coupler at a surface. The optical grating coupler may include a first semiconductor layer having a first base and first fingers extending outwardly from the first base. The optical grating coupler may include a second semiconductor layer having a second base and second fingers extending outwardly from the second base and being interdigitated with the first fingers to define semiconductor junction areas, with the first and second fingers having a non-uniform width. The electro-optic device may include a circuit coupled to the optical grating coupler and configured to bias the semiconductor junction areas and change one or more optical characteristics of the optical grating coupler.