RF-inspired silicon photonics: Beamforming at optical frequencies

After decades of research and developments, radio frequency monolithic phased arrays are becoming mainstream for automotive radar and high-speed wireless communication applications. Optical beam steering has been around for several decades as well; but, they have not been as widely used partially due to their relatively higher cost and form factor. Advancement in fabrication technology may enable monolithic optical phased arrays with low cost, size, and power consumption for a wide range of applications such as imaging, lidar, display, and holography. In this paper, we cover architectural considerations, device structures, and complete realization of a monolithic optical phased array transceiver in a commercial CMOS SOI process. Throughout the paper, we draw analogies and side-by-side comparisons between radio frequency and optical realizations of optical phased arrays and associated building blocks.