Underwater blue-green LED communication using a double-layered, curved compound-eye optical system

Optical receiving systems with single-lens structures have problems such as low receiving efficiency and small field of view when applied to underwater optical wireless communication systems. In this study, a design scheme for a double-layered fly-eye-lens optical system with wide-angle focusing is proposed. Based on the analysis of the LED light source transmission model and seawater channel, the optical-power receiving equation of the fly-eye lens system is deduced. The fly-eye-lens receiving system was designed and simulated using Zemax according to the geometrical optics principle of the lens array. An experimental device for measuring the insertion loss and receiving efficiency of an underwater blue-green LED communication system was built, and the optical power of the receiving optical system was experimentally measured. For the link distances of 1, 3, and 5 m, the received optical power of the double-layered-compound eye system was higher than that of the single-layered system, with a power increase of 72%, 65%, and 60%, respectively. The results show that the double-layered fly-eye-lens receiving antenna can significantly improve the optical power received by the receiving end; therefore, this antenna structure has strong practicability and good development prospects in the field of underwater optical wireless communication.