Performance analysis of free space optical link at 650 nm wavelength

Free-space optics, as the name implies, means the transmission of optical signals through free space or air. Such propagation of optical capacity through air requires the use of light. Light sources can be either LEDs or lasers (light amplification by stimulated emission of radiation). FSO is a simple concept that is similar to optical transmission using fiber-optic cables. FSO meets the need of modern wireless communication by providing safer and high speed connectivity. License free operation, low cost, high security and long range are some of its various features which add to its usefulness. In this paper FSO link is optimized for operation under 650nm wavelength. Simulation results provide maximum link range of 1000 m using visible red laser beam. The bit rate achieved for optimized link is 1.25 Gbps The achieved values of Bit Error Rate (BER) and Quality Factor(Q) are 10^-21 and 9 respectively. The paper also discusses simulation study of comparison of NRZ and RZ modulation schemes at 650 nm.