Beam Tracking for Ultraviolet Communication Using Single PMT

In this article, we design and demonstrate a beam tracking system on the receiver side for ultraviolet (UV) communication using a single photomultiplier tube (PMT). Specifically, we investigate the properties of the angle-domain channel for UV communication. We characterize the effects of metallic housing and the spatial nonuniformity of the PMT on the angle-domain channel, both of which can significantly impact the channel’s performance. To adjust the orientation of the PMT and maintain satisfactory communication in mobile UV systems, we propose a beam alignment algorithm based on coordinate search and a beam tracking algorithm based on pattern-search. A real-time system is developed to test the performance of these algorithms. Experimental results show that the proposed beam alignment algorithm can quickly search for the incident direction, while the beam tracking algorithm effectively tracks a moving transmitter at a rate of 5.5 degrees/s, ensuring a reliable communication link. The proposed beam alignment and tracking scheme uses only a single PMT, making it lighter and more cost-effective compared to the PMT array scheme, and is thus well-suited for deployment in compact UV communication terminals.