A photonic variable RF delay line for phased array antennas

It is shown that by applying spatial frequency-dependent phase compensation in an optical heterodyne process a variable RF delay line can be synthesized over a prescribed frequency band. Experimental results which demonstrate the performance of the delay line with regard to both maximum delay and resolution over a broad bandwidth are presented. A spatially integrated optical system is proposed for control of phased array antennas. The integrated system provides mechanical stability essentially eliminates the drift problems associated with freespace optical systems, and can provide high-packing density. The approach uses a class of spatial light modulator known as a deformable mirror device and leads to a steerable arbitrary antenna radiation pattern of the true time-delay type.>