Performance Investigation of the Free Space Optics Link based Communication using DOE scheme at 1550nm

FSO is a terrestrial OWC system used for point-to-point communication and operates at near infrared (IR) frequencies (750–1600 nm). It is a laser driven Communication based on line of sight (LOS) enabling technology for the transmission and reception of information carrying light signals through the atmosphere. For the same, it uses light sources and light detectors, i.e., laser diodes and photodiodes, respectively. The real motive behind using FSO is to do away with the cost, time, and effort in laying fiber optic cables without adversely impacting high data rates for transmitting voice, image, text, video, or any other file. In recent years, Free space based optical communication has developed and grown rapidly and has been widely used in applications like satellite laser based communication, radar detection, and other fields. Space optical communication based system includes a TX-RX antenna system and a coupling system. The research of space optical communication system often separates the antenna systems and the coupling system for discussion. When analyzing TX-RX antenna systems, geometric optics is generally used. Based on ancient diffraction theory, the performance of space optical communication systems consisting of a transmitter antenna, receiver antenna, and fiber coupling based systems are analyzed. Besides, several practical situations are also considered such as the defocusing of the TX-RX antenna and the deviation of the fiber. The longer or greater the transmission distance, the greater the effect of diffraction. When the transmission distance is short, the defocusing of the primary mirror will help it improve the transmission efficiency of the given system.