Design of multi-beam free space optical communication system for mitigation of atmospheric and geometric nonlinearities

Free space optical communication (FSO) has occupied a significant hold among researchers nowadays because of wider bandwidth, easier deployability and greater immunity toward links. To carry out line of sight transmission, FSO requires clear climatic conditions with non-turbulent atmosphere. The present work aims at mitigating the effects of nonlinearities present in the atmosphere and link geometry under turbulent atmospheric conditions. While single beam is not capable alone to overcome the turbulence effects in FSO communication, therefore, we have proposed a high data rate multiple beam FSO communication system. For modeling the channel with moderate turbulences, the modified Gamma-Gamma (G-G) distribution has been used. Further, on comparison with single-beam FSO, the multi-beam FSO demonstrates an improved Q-factor which reveals reduction in attenuations that is encouraging for an efficient communication link. With spatially diverse transmitters, a significant enhancement in FSO link length, signal-to-noise ratio and power has been achieved.