design and fabrication of underwater FSO system

iIn this article, the consideration of design and manufacturing method of laser base under water digital communication system for transformation of every kind of data (video, image, sound, text) is presented. By studying the effects of transmission channel (water) on the propagation properties of laser, 532 nm has been chosen as laser source wavelength. Then, the transmitter and receiver systems are discussed. Each of these systems includes two main parts: software and hardware. In software parts, to control transmission, receiption and processing of the every kind of data, essential codes have been written in MATLAB software for serial port. In hardware parts, computer and laser TTL modulation circuit in transmitter and detector circuit and computer in receiver are related by USB to serial converter FTDI chip. Finally, the field test shows that this system is able to best communicate (every kind of data) in 100 m link length by 3 Mb/s rate.