In this paper, the implementation of a dense wavelength division multiplexing (DWDM) 32 × 40 Gbps (1.28 Tera bit/s) for the free-space optical (FSO) communication system is investigated. Analysis is performed for return-to-zero (RZ) and non-return-to-zero (NRZ) line codes for 1 km free space optic length. Motivation to the current analysis is to compare RZ and NRZ lines codes in the DWDM-FSO communication system and it is found that the NRZ line code is better than RZ code. A 1.28 Tb/ps wavelength division multiplexed communication system for free space optic channel workplace has been discovered in which 32 channel each of 40 Gbps data streams are combined using wavelength division multiplexed. The study includes the attenuation caused by atmospheric effect and beam divergence. Bit-error rate (BER), quality factor (Q), and eye diagram are indicator of performance evaluation. By comparing one can get a promising system to the high capacity access network with more bandwidth, cost effective and good flexibility.