Performance investigation of long-haul high data rate optical OFDM IM/DD system with different QAM modulations

In this paper and as a first time, we have designed and simulated 100 Gbps long haul intensity modulation and direct detection (IM/DD) optical orthogonal frequency division multiplexing (OFDM) system with high order modulation techniques by using optisystem software QAM IM/DD OFDM system was analyzed and simulated to provide high data rate for downstream signal by using dispersion compensation fiber (DCF) inside fiber link. 4-QAM OFDM system demonstrated the best BER performance compared to other simulated systems for long haul transmission distance. For comparison and investigation, important results as eye diagram, Q factor, Eb/No and BER are explained against propagation length for every simulated system.