In one embodiment, a device is disclosed that includes: a first substrate, a plurality of antennas adjacent the first substrate; a plurality of oscillators integrated in the first substrate, each oscillator providing an output signal to drive a corresponding subset of the antennas; and a plurality of photodetectors corresponding to plurality of oscillators, each oscillator being adapted to injection lock its output signal to an electronic photodetector signal from the photodetector produced in response to an illumination of the photodetectors with a free-space optical signal modulated such that the photodetector signals are globally synchronized with each other, whereby the output signals driving the plurality antennas are also globally synchronized across the plurality of antennas.