Free space optical communication (FSO) utilizes an optical system to transmit message signals through the air directly from the source to the receiver. With benefits such as fast data rates, licenses free spectrum, secure communication, quick deployment, and cheap maintenance costs, FSO systems are highly appealing for integration into next-generation wireless networks. However, the performance of the FSO system is significantly harmed by atmospheric factors such as haze, fog, rain, and snow. Fog significantly reduces the optical signal compared to all weather conditions. Therefore, a thorough metrological investigation of the region should be conducted prior to creating the FSO connection. This study proposed an FSO system with a capacity of around 1376 Gbps by integrating three different multiplexing methods. These techniques include polarization division multiplexing (PDM), wavelength division multiplexing (WDM), and coherent optical orthogonal frequency division multiplexing (CO-OFDM) which helps to achieve this high capacity and high spectrum efficiency of 3.4 bps/Hz. Using the quadrature amplitude modulation (4-QAM) technique, four WDM channels, each containing 344 * 109 bits per second (bps) of data, are carried across a minimum of 1.84 km and a maximum of 67.1 km FSO connection. Additionally, the proposed hybrid multiplexed PDM-CO-OFDM-WDM-FSO system’s performance is examined under a variety of foggy weather conditions and compared with the recent research published that shows highest achieved distance with maximum data capacity. The findings demonstrate that even under the most challenging channel conditions, the maximum link range is attainable with a minimum allowable bit error rate (BER) of log (BER) ≤ −2.42, using pre- and post-optical amplification between FSO channels.