Various 3D sensing, imaging, illumination, and ranging uses, as well as their convergence in new lidar technology, could be made possible by implementing optical phased arrays (OPAs) in integrated photonic circuits. Although large aperture sizes are required to enable medium- to long-range lidar, current integrated OPA approaches must be scaleable regarding control complexity, power consumption, or optical efficiency.
The serpentine OPA (SOPA), a novel OPA concept by researchers, addresses these basic issues and allows architectures that scale up to large apertures. The SOPA supports passive, 2D wavelength-controlled beam steering and is built on a serially interconnected array of low-loss grating waveguides. Scalable tiling of SOPAs into large apertures (e.g., for 3D sensing) with a high fill factor is also made possible by an essentially space-efficient design that folds the feed network into the aperture.
The SOPA is demonstrated empirically using a 1450–1650 nm wavelength sweep to generate 16,500 addressable spots in a 27–610 array. They also show far-field interference of beams from two different OPAs on a single silicon photonic chip. It is the first move toward developing long-range computational imaging lidar based on novel active aperture synthesis techniques.
A free-space optical beam can be formed and electrically guided to be emitted from or received by an on-chip aperture using optical phased arrays (OPAs) used in integrated photonics.
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