Gbps data is transmitted over FSO link by applying WDM technique and compared with WDM-FSO system with Polarization Interleaving by varying the beam divergence angle from 1 mrad to 5 mrad. Next two FSO-WDM

111 www.ijeas.org  Abstract— This work is focused to carry out investigation of WDM Free Space Optical transmission when even and odd channels are orthogonally polarized. In this work 8 independent channels each having capacity of 1.56Gbps are transmitted over free space optical link of 15 kilometer at different beam divergence angles. Systems with and without polarization interleaving are compared here in this paper. Then after WDM-FSO polarization interleaving systems with 16 channels are realized. The bit rate of each channel is increased to 8Gbps and it has been found that WDM-FSO system with polarization interleaving having 16 channels and 128Gbps bitrates of whole system is optimized to work properly up to 25 kilometer range after its comparison with WDM-FSO polarization interleaving system having 8 channels and capacity 12.48 Gbps of whole system. Performance is measured in the terms of Quality Factor and Eye Diagrams.