29.5 A Single-Chip Optical Phased Array in a 3D-Integrated Silicon Photonics/65nm CMOS Technology

The realization of a low-cost and robust optical beam-steering platform is a key enabler for a number of applications, including light detection and ranging (LIDAR) and free-space optical communications (FSO). Optical phased arrays (OPAs) have emerged as a promising solution, due to advancements in photonic integrated circuits (PIC) foundry processes, which have enabled high-precision fabrication of PICs with a large number of components [1]–[3]. In order to meet steering range and directivity requirements in systems such as autonomous vehicles, a clear path to scaling OPAs to millimeter-scale apertures with thousands of tight-pitched antenna elements is critical. As the element count grows, independent phase control for each element becomes crucial since maintaining coherence between elements becomes more difficult due to process variations. Moreover, independent control allows for unique system capabilities, such as multi-beam formation and converging/adaptive beams, which makes OPAs a particularly attractive solid-state beamforming technology.