Development of Free Space Optical Link for Broadband Data Communication

To transfer high speed data streams, a line of sight (LOS) broadband free space optical (FSO) communication link has been designed between two private local LANs located at an aerial distance of about 2 km. A laser diode (LD) – avalanche photodiode (APD) combination operating at 1550nm is used to work as an optical trans-receiver system while an Erbium-doped optical amplifier (EDFA) is used to boost up the laser power for launching into the atmosphere. In this work optical pulse position modulation (PPM) along with convolution coding is used at the receiver side. The system performance impairment due to atmospheric turbulence such as scintillation and attenuation produced by fog and rain are theoretically analyzed to study the channel characteristic of the FSO link. The preliminary results of simulation will be presented for predicating the performance of FSO link operating under normal weather conditions