Free Space Optical Communication: A Review
With the worldwide demand for larger bandwidth and greater mobility there is a rapid advancement of broadband wireless communications. The high capacity and low loss of optical fibre has seen its exploding growth in the last few decades in the LAN's and WAN's. Free space optical (FSO) wireless communication has emerged as a viable technology for bridging the gap in existing high date rate fibre network and as a temporary backbone for rapidly deployable mobile wireless communication infrastructure. Free space optical communication offers the potential to send large amount of data security over moderate distances without the expense of laying fibre optic cable. The technology is helpful where the physical connection of the transmitter and receiver locations is difficult. These robust systems which establish communication links by transmitting laser beams directly through the atmosphere, have matured to the point that mass produced models are now available. FSO system offers many features among them being the low start up and operational cost, rapid development and high fibre like bandwidth. It offers capacities in the range of 100Mbps to 2.5Gbps and demonstration systems report data rates as high as 160Mbps.It is a line of sight technology that currently enables optical transmission up to 2.5Gbps of data, voice and video communications through the air, allowing optical connectivity without deploying fibre optic cables or securing spectrum licences. Even though FSOs provide high security as its laser beams cannot be determined with the devices like spectrum analyser or RF meters, there are some challenges (atmospheric turbulence, scintillation, object sway) in the implementation of it.