First experimental demonstration of faster-than-Nyquist PDM-16QAM transmission over standard single mode fiber

We demonstrate faster-than-Nyquist (FTN) transmission with a novel mitigation scheme of intercarrier interference. To the best of our knowledge, it is the first experimental demonstration of FTN PDM-16QAM transmission over standard single mode fiber (SSMF). Due to the use of maximum likelihood sequence detection and multi-input multi-output processing for severely overlapped Nyquist-PDM-16QAM carriers, 5.4-dB optical signal-to-noise ratio improvement is experimentally observed under the scenario of 2×16-GBd PDM-16QAM back-to-back transmission with a carrier spacing of 15 GHz. A net spectral efficiency up to 7.68 b/s/Hz is achieved by transmission of a 15-GHz spaced dual-carrier superchannel over 960-km SSMF, with hard decision forward error correction taken into account. Furthermore, FTN superchannel transmission with carrier spacings of 14 and 15 GHz are successfully realized over 960- and 1920-km SSMFs, respectively.