Planar Luneburg Lens System for Two-Dimensional Optical Beam Steering

An integrated optical beam steering device includes a planar Luneburg lens that collimates beams from different inputs in different directions within the lens plane. It also includes a curved (e.g., semi-circular or arced) grating coupler that diffracts the collimated beams out of the lens plane. The beams can be steered in the plane by controlling the direction along which the lens is illuminated and out of the plane by varying the beam wavelength. Unlike other beam steering devices, this device can operate over an extremely wide field of view—up to 180°—without any aberrations off boresight. In other words, the beam quality is uniform in all directions, unlike with aplanatic lenses, thanks to the circular symmetry of the planar Luneburg lens, which may be composed of subwavelength features. The lens is also robust to misalignment and fabrication imperfections and can be made using standard CMOS processes.