Fast and low grating lobe multi-beam steering with a subarray level unequally spaced optical phased array

A grating-lobe-suppressed optical phased array (OPA) based on an unequally spaced technique is proposed to realize multi-beam steering, in which the multi-beam is achieved using the subaperture (SA) technique. The element distribution in SA is optimized by a modified genetic algorithm to minimize peak sidelobe levels (PSLL). The results show that grating lobes can be well suppressed using the proposed technique within the whole scanning range o f the beams. The PSLL of the optimized unequally spaced OPA reaches as low as 0.21 in the +/- 5 degrees beam direction, which is much better than the equally spaced OPA. Simultaneously, multi-beam asynchronous scanning can be achieved, which significantly improves the accuracy and flexibility of beam steering control. Besides, the simulations show that the spacing range between adjacent elements and the element number should be appropriately chosen to achieve better sidelobe suppression and a narrow beam width. (C) 2021 Optical Society of America