Now a day’s communications with high data rate as well as more band width is the most important need of the whole world. Free space optical communication network (FSO) is line of sight wireless communication technology. In FSO communication between transmitter and receiver takes place, data carried by an optical laser beam light transferred to the free space rather than fiber glass. It has many advantages over other communication technologies like unlicensed bandwidth, more security, easy to install etc. but FSO chann el highly sensitive to affected by bad weather condition namely rain, fog, snow, dust. Due to bad weather conditions transmission of data from one point to another point becomes difficult, transmitted signal strength reduced at end point of transmission, the data rate also decreases. In this work, performance analysis of Carrier Suppressed Return to Zero (CSRZ), Non-Return to Zero (NRZ) and Return to Zero (RZ) coded FSO communication using log normal channel model under different weather conditions has been done at two operating bands. These bands are C-Band and L-Band. For both bands, varying transmission distance(1-10Km), input power (5-50dBm), divergence angle (0-9mrad) and attenuation (0.19-85dB/Km) at 100GHz channel spacing with different type of filters and amplifiers are used. In this thesis, result analysis shows that RZ with lowpass Chebyshev filter and EDFA has super quality than CSRZ and NRZ for short distance transmission and low attenuation. But TW-SOA enhance the performance of CSRZ, NRZ and RZ at high attenuation. Simulation conducted along with Opti- system simulator in terms of graphical plot. Keywords: Q-factor, FSO, Propagation loss, WDM, DWDM, Attenuation, Opti-system.