An Automatic Alignment Bidirectional Visible Light Communication System Based on Red Laser Diode

In recent years, visible light communication using LEDs has attracted great attention. However, LED's narrow modulation bandwidth restricts the achievable data rate. In that case, researches on LD-based VLC are widely proceeding. Because of the high beam convergence of LDs, the terminal devices must be strictly aligned. In this paper, we propose an automatic alignment VLC system based on red LDs. By using the camera and the galvo, we demonstrate a mobile real-time VLC system over a distance of 0.6 meter and a field angle of ±10°. Based on the Gigabit Ethernet protocol, the system can provide a TCP data transmission of 909Mbps.