OFDM-based broadband underwater wireless optical communication system using a compact blue LED

We propose and experimentally demonstrate an IM/DD-OFDM-based underwater wireless optical communication system. We investigate the dependence of its BER performance on the training symbol number as well as LED's bias voltage and driving voltage. With single compact blue LED and a low-cost PIN photodiode, we achieve net bit rates of 225.90Mb/s at a BER of 1.54×10−3 using 16-QAM and 231.95Mb/s at a BER of 3.28×10−3 using 32-QAM, respectively, over a 2-m air channel. Over a 2-m underwater channel, we achieve net bit rates of 161.36Mb/s using 16-QAM, 156.31Mb/s using 32-QAM, and 127.07Mb/s using 64-QAM, respectively. The corresponding BERs are 2.5×10−3, 7.42×10−4, and 3.17×10−3, respectively, which are all below the FEC threshold.