Fast and wide-range optical beam steering with ultralow side lobes by applying an optimized multi-circular optical phased array

A multi-circular optical phased array (OPA) is proposed and investigated through simulation to realize fast and wide-range optical beam steering with ultralow side lobes. The proposed multi-circular OPA has a circularly symmetrical distribution, and its radical element spacings are optimized by a modified genetic algorithm to achieve the best side lobe suppression. Specifically, the peak side lobe level (PSLL)of the far-field pattern in 0 degrees beam direction reaches as low as 0.0715 for a 73-element optimized multi-circular OPA, which is much better than a multi-circular OPA with uniform radical element spacing (the PSLL is 0.3686). The prominent feature of the proposed OPA is that, once the OPA is optimized towards a specific elevation direction by the modified genetic algorithm, a wide-angle optical beam steering with nearly the same side lobe suppression can be achieved without updating the OPA distribution, which makes it possible for fast optical beam steering over a wide scanning range. In the simulation, ultralow side lobe beamsteering with an elevation angle from 0 degrees to 30 degrees and an azimuth angle from 0 degrees to 360 degrees is achieved with the PSLL variation less than 0.001. The relationship between the optimized PSLL and the elevation angle used for OPA optimization is also investigated, which is helpful in achieving the best side lobe suppression for different scanning ranges. The proposed OPA is expected to find applications such as laser radar, high-resolution display, and free space optical communications. (C) 2018 Optical Society of America.