Performance evaluation of free space optical link using mid and far infrared wavelengths in turbulent atmospheric conditions

Free space optical communication (FSO) links have gained huge popularity in last couple of decades. In this paper FSO link performance has been studied by calculating the DSNR and link margin for wavelengths of mid and far infrared regions, so as to find out the validity of popular myth that performance of FSO systems improves with selection of longer wavelengths. Although most of the FSO systems are intensity modulated (IM) - Direct detection (DD) systems which are easy to implement but improved BER can be achieved using higher modulated systems like 8- PPM. However irrespective of the choice of modulation technique i.e. weather OOK or 8- PPM modulated FSO was used, selection of longer wavelengths did not yield any improvement in Bit Error Rate (BER).