Comparison of 100G PAM-8, CAP-64 and DFT-S OFDM with a bandwidth-limited direct-detection receiver

We present a detailed comparison of applying three advanced modulation formats including pulse amplitude modulation-8 (PAM-8), carrier-less amplitude and phase modulation-64 QAM (CAP-64), and discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S OFDM) with a bandwidth-limited direct-detection receiver for 100 Gb/s/lambda optical transmission systems. These modulation formats are all experimentally demonstrated with corresponding digital signal processing (DSP) algorithms. The comparison is carried out to evaluate the performance of each modulation format in terms of nonlinear equalization, received optical power and optical signal to noise ratio (OSNR). Our experimental results show that only 112 Gbit/s DFT-S OFDM is successfully achieved over 50 km of SSMF under the hard decision-forward error correction (HD-FEC) threshold of 3.8 x 10(-3). (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement