DFT Spread Spectrally Efficient Frequency Division Multiplexing for IM-DD Transmission in C-Band

In this article, we propose and experimentally demonstrate a new discrete Fourier transform spread (DFT-S) spectrally efficient frequency division multiplexing (DFT-S SEFDM) system. DFT-S technique is adopted to reduce the peak-to-average-power-ratio (PAPR) of SEFDM signal in optical intensity modulation and direct detection (IM-DD) system for the first time. The existing detection algorithms for SEFDM signal, such as logarithmic-maximum-a-posterior (log-MAP) Viterbi and cascaded binary-phase-shift-keying iterative detection (CBID), are successfully modified to our DFT-S SEFDM system. Experimental results show that DFT-S SEFDM outperforms conventional SEFDM owing to its lower PAPR. In our test, to verify the benefits of our scheme, a net data rate of beyond 100 Gb/s can be achieved after 2-km standard single mode fiber (SSMF) transmission, and DFT-S SEFDM also can outperform DFT-S DMT owing to its tolerance to bandwidth limitation. We further verify the advantage of DFT-S SEFDM in IM-DD C-band system, and show its resistance to the impact of dispersion-induced power fading.