1 Gb/s Underwater Optical Wireless On-Off-Keying Communication with 167 MHz Receiver Bandwidth

We demonstrate bandwidth-limited 420 nm, 1.1 Gb/s on-off keying (OOK) based underwater optical wireless communication (UOWC) with only 167 MHz bandwidth by using maximum likelihood sequence estimator (MLSE), with a record spectral efficiency of 6.58 b/s/Hz for OOK based UOWC communication. The MLSE is adopted here to compensate the bandwidth limitation mainly caused by the photodiode (3 dB bandwidth is 150 MHz) at the receiver. By using 7 and 10 taps MLSE detection and assuming BER threshold of 3.8×10 −3 , the bitrate that can be achieved after 1 meter underwater transmission is 0.9 and 1.1 Gb/s, which is more than two times of data rate using conventional symbol-by-symbol detection.