Experimental verification of diffused laser beam-based optical wireless communication through air and water channels

Abstract

In this paper, the authors have made discussion on the solutions of alignment problem in wireless optical communication. Traditional light sources like light-emitting diode (LED) and laser diode (LD) have their respective advantages, but it is hard to combine the merits of both LED and LD such as large coverage, high modulation bandwidth and high color purity. Therefore, the combination of optical diffuser and LD was proposed to ensure high data rate while obtaining larger coverage area, implying improved system robustness. Through the experiments, the performance of LD beam diffused by engineered diffuser (ED) and ground glass diffuser (GGD) in air and water channels were verified at a data rate of 1 Gbps. In a 2-m air channel, within the deflection angle range of 12° or a lateral deviation tolerance of 41.5 cm, ED and GGD beam both provided 1-Gbps communication link with bit error rates (BERs) under the forward error correction (FEC) threshold of 3.8×10−3. In a 2-m water channel, the GGD beam covered the range of 0°–6° or a lateral deviation tolerance of about 20.9 cm, while the ED can cover the range of 6°–12° and in 0°–6° it falls short of FEC criterion.