Automatic Gbps Receiver for Mobile Device in Beam-Steered Infrared Light Communication System

This work presents a beam-steered infrared light communication (BS-ILC) system that enables high data rate wireless optical transmission to individual mobile users. The BS-ILC system comprises arrayed waveguide grating router-based optical antennas, camera-based user localization, and optical receivers (each integrated with an infrared tag). A high-speed photodetector has typically a small active area to minimize its junction capacitance, but this small size will result in a very limited field of view (FoV), which is detrimental to an optical wireless system aimed to provide some degree of mobility to users. Thus, the desired BS-ILC system requires precise and automatic alignment to establish a high-performance optical link between users and optical antennas. In this work, we propose an optical wireless receiver that can automatically align its orientation with respect to the optical antenna to ensure the light angle of incidence within the receiver's FoV. The automatic receiver consists of a motorized actuator and an optimization control algorithm. The actuator controls the orientation of the receiver, and the optimization algorithm is developed to accelerate the searching process of the actuator. In an indoor laboratory system setup, the amount of less than 200 ms has been demonstrated to establish gigabit-per-second optical link, and seamless transmission has also been realized for the mobile receiver while on the move with the FoV of ± 0.6°.