A device includes an input waveguide on a base. The input waveguide guides a light signal through a light-transmitting medium to a light sensor. The light sensor includes a sensor waveguide on the base. The sensor waveguide includes a light-absorbing medium that receives the light signal from the input waveguide. The light-absorbing medium has one or more continuous doped regions that are each positioned such that an application of electrical energy to the doped regions forms an electrical field in the light-absorbing medium. One or more of the doped regions has a first portion that is located within the light-absorbing medium and a second portion located outside of the light-absorbing medium. The device also includes an electrical conductor for applying the electrical energy to one of the doped regions. The electrical conductor contacts the portion of the doped regions that is located outside of the light-absorbing medium.