The performance of the subcarrier multiplexing with spectral amplitude code optical code division multiplying access (SCM˗SAC˗OCDMA) system based on Free Space Optic (FSO) by using MD code has been investigated, which reduces the MAI and increase the number of users. The proposed system can overcome the weather condition problems, i.e., haze. The proposed system shows superior performance in terms of bit error rate (BER). For example, in the heavy haze condition of Malaysia, when the FSO link is 23.3 km and the value of BER becomes 2.7×10 -9 . Thus, the proposed system is a potential candidate for future broadband access solutions in communication networks. The proposed SAC˗OCDMA˗FSO using the SCM system shows better performance compared with the conventional SAC˗OCDMA˗ FSO system and the number of users improves by 31.8%.