Water Tanks as Lenses for Optical Wireless Power Transfer

Abstract

In this paper, the transmitting efficiency of optical wireless power transfer (OWPT) systems through different water environments is studied, where light emitting diodes (LEDs) and silicon solar cells serve as the optical transmitters and receivers, respectively. It is then found that clean water tanks can significantly help improve the OWPT transmitting efficiency in the air, due to Snell’s law of refraction. In other words, clean water tanks are simple and low-cost, yet effective optical lenses. Therefore, we propose to employ clean water tanks to improve the OWPT efficiency not only in the air but also in unclean underwater environments. Extensive experiments are carried out, whose results confirm our proposal above. More specifically, a plastic tank filled with clean tap water helps boost the OWPT efficiency in the air by 68.85% and 213.33% under the illumination of a high-power blue LED and a low-power white LED array, respectively. In addition, a clean plastic water tank can help increase the OWPT efficiency in an unclean seawater environment by 28.7%. Furthermore, a mathematical model is proposed to represent the dependence of the transmitting efficiency through a water tank to the water level, which is then verified through different experiments.

Keywords

• Optical wireless power transfer
• optical lenses
• water tanks
• underwater wireless power transfer