Effects of focused and collimated laser beams on the performance of underwater wireless optical communication links

In this paper, the optical transmittance and bit error rate (BER) of focused and collimated laser beams are experimentally examined in an underwater optical wireless communication link with different water types. The water types used are fresh water, salty water and their variations with maalox in order to obtain turbid water. In bit error rate (BER) analysis, on-off keying (OOK) is used together with Bose-Chaudhuri-Hocquenghem (BCH) and convolutional codes. Results show that salt and maalox content decreases the transmittance, the convolution codes have better BER performance than BCH codes under the same modulation scheme (i.e., OOK) and focusing improves both the transmittance and BER performance as compared to collimated beams.