Photonic control of phased arrays using analog vector modulation

A compact free-space/solid optics photonic controller for phased array antennas/transducers is introduced that uses the principle of in-phase (I) and quadrature (Q) vector modulation via two dimensional (2-D) spatial light modulators (SLMs). The SLMs are used as distributed optical gain control devices to implement the vector modulation operation required to generate the desired radio frequency (RF) signals with the correct phase and amplitude values. In one design, the system is fed by four independent lasers where one pair of lasers is mutually incoherent with the other pair of lasers. These lasers are modulated (directly or externally) by separate forms (different phase shifts: 0, 90, 180, 270 degrees) of the input RF carrier. Depending on the phase and amplitude of the carrier required for the nth antenna/transducer element, two predetermined laser beams from the nth pixel locations of two of the preselected SLMs are optically combined in intensity via a photosensor to generate the desired RF signal. In a similar fashion, the system can provide independent control for all N elements of the phased array