Comparison of different modulation techniques for optical OFDM Intensity Modulation and Direct Detection IM/DD system

In this article, we have demonstrated an Optical Orthogonal Frequency Division Multiplexing (OFDM) Intensity Modulation and Direct Detection (IM/DD) system with different modulation techniques such as Quadrature Amplitude Modulation (QAM) and Phase Shift Keying (PSK). 16 QAM and 16 PSK modulation with different number of subcarriers are applied to IM/DD system to achieve the best Bit Error Rate (BER) performance. According to best BER, the downstream data rate and transmission distance were choosing to be 10 Gbps and 100 km, respectively. Compared with other modulation techniques, IM/DD system with 16 QAM and 128 subcarriers achieved the best BER performance.