Research on the Optical Receiving Performance of Underwater Wireless Optical Communication System Based on Fresnel Lens

In response to the practical demands of high rate, long distance, low cost and miniaturized equipment for underwater wireless communication, an underwater wireless optical communication experimental system with Fresnel lenses as optical receiving antennas has been established. Using 488 nm and 520 nm lasers as the test light sources, the relationship curves between the focusing performance of several Fresnel lenses with different light transmission aperisions and focal lengths after passing through the underwater channel and the lens surface, laser wavelength, and incident angle were obtained. The influence of the laser incident angle on the focusing spots of 488 nm and 520 nm lasers was measured. The experimental results indicate that the Fresnel lens exhibits excellent light concentration performance, with the overall system concentration efficiency being higher than that of conventional lenses, significantly enhancing the received optical power in underwater wireless optical communication systems. Additionally, configuring the sawtooth surface as the incident surface of the Fresnel lens can improve the concentration efficiency by approximately 1% to 5% compared to using a smooth incident surface.