Various embodiments of the present invention are directed to dynamically and electronically reconfigurable optical devices that can be operated as a lens or prism for incident beams of electromagnetic radiation. The optical devices include a phase-modulation layer (1501) disposed between first and second nanowire layers (1502,1503). Overlapping nanowires can be electronically addressed to implement a selected effective refractive index pattern of one or more regions (1510) of the phase-modulation layer, such that each region refracts a portion of an incident beam of electromagnetic radiation having a wavelength of interest in order to focus, diverge, or bend the incident beam.