Performance estimation of 100 GB/s hybrid SACOCDMA-FSO-MDM system under atmospheric turbulences

Mode division multiplexing (MDM) is an emerging multiplexing technique that simultaneously transmits independent channels through a spatial light modulator (SLM). Further, Spectral amplitude coding optical code division multiple access (SAC-OCDMA) is an encouraging invention because it gives an appealing answer for burst and asynchronous environment. In addition, free space optics (FSO) provides a cost-effective, secure, high data rate for last mile access compared to other systems. In this paper, a hybrid 100 GB/s SACOCDMA-FSO-MDM system is proposed, and its performance is estimated by using four SAC-OCDMA codes that are Zero Cross Correlation (ZCC), Random Diagonal (RD), Multi Diagonal (MD), and Enhanced double weight (EDW) under atmospheric turbulences such as haze, rain, and clear weather. Laguerre Gaussian (LG) modes (used for MDM) and direct detection (DD) method are used for the construction of the system using 10 channels; each carries 10 Gb/s data. Results specify that the ZCC code is more suitable under all the atmospheric conditions as it possesses no cross-correlation, lesser noise that diminishes the hardware's complexity. For clear weather, the ZCC code gives a BER of 10^–29 at a maximum distance of 22 km.