In underwater wireless optical communication (UWOC), one of the key technologies is to generate high-speed communication signal for transmitter. In this paper, we designed such transmitter based on laser diode (LD) arrays, which is composed of three LDs with central wavelength 450nm. The modulation format is non-return-to-zero on-off keying (NRZ-OOK) with data rate up to 50Mbps. Using such transmitter, we established a point-to-point underwater wireless optical communication link in an experimental tank with 20m length, 20m width and 14 depth. The experimental results show that the maximum error-free data rate of the system can reach 50Mbps with 10.7m transmission distance, while the maximum error-free transmission rate is 30Mbps with 14.7m transmission distance. These results verify the feasibility of the LD-based modulation scheme for high-speed UWOC applications. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.