Design of transmitter and receiver for experimental blue-green laser communication system

An experimental blue-green laser communication system was developed using optical pulse position modulation (PPM) to study the feasibility of high-rate underwater communication among submerged objects. As a primary optical modulation means, PPM modulation is reviewed firstly. By comparison with other means, the conclusion was drawn that PPM has lower power requirement and it is a near optimal modulation for background-limited optical communications. For establishing laser beam propagating through the channel with modulated information through different pulse positions from the transmitter to the receiver, the transmitter subsystem and the receiver subsystem are developed and the key techniques are described separately in detail. Results indicated that the whole blue-green communication system was compact, efficient, reliable and inexpensive, and achieved a high-speed rate communication up to megabits per second and a reasonably low error rates.