Disclosed is an apparatus and method including a semiconductor substrate including a waveguide having a guiding region and one or more bounding regions coupled to the guiding region; a first PN junction disposed in the substrate and coupled to one or more of the one or more bounding regions; and dopant atoms disposed within the semiconductor substrate at the PN junction. An alternate embodiment includes a memory device, having a waveguide having a guiding region for propagating a radiation signal; an influencer, coupled to the waveguide, for controlling a characteristic of the radiation signal propagating in the waveguide between a first mode and a second mode; and a latching layer, coupled to the guiding region and responsive to the influencer, for retaining the characteristic of the radiation signal for a memory cycle.