Optimal cascade operation of optical phased-array beam deflectors.

An optimal strategy for cascading phased-array deflectors is presented that allows for high-resolution random-access beam steering with continuous scan-angle control but requires a minimum number of control lines. The system is analyzed theoretically by use of a Fourier optics approach and then verified experimentally. A pair of 32-channel optical phased arrays fabricated by use of surface electrodes on lanthanum-modified lead zirconate titanate (PLZT) was sandwiched together to form a functional two-stage phased-array cascade. Experimental results from the PLZT-based two-stage deflector are presented that confirm the performance enhancements of the optimized cascading technique. A phase-staggered discrete-offset-bias protocol for controlling the cascaded system is shown to be optimal in terms of maximum diffraction efficiency and minimum number of control lines, while still providing for full analog scan control.