Terabit Superchannel Transmission： A Nyquist-WDM Approach

摘要

In this work, we focus on enhancing the network reach in terabit superchannel transmission by using a noise-suppressed Nyquist wavelength division multiplexing (NS-N-WDM) technique for polarization multiplexing quadrature phase-shift keying (PM-QPSK) subchannels at different symbol-rate-to-subchannel-spacing ratios up to 1.28. For the first time, we experimentally compare the transmission reach of this emerging technique with that of no-guard-interval coherent optical orthogonal frequency-division multiplexing (NGI-CO-OFDM) on the same testbed. At BER of 2 x 10 3 and 100 Gbit/s per channel, an NGI-CO-OFDM terabit superchannel can transmit over a maximum of 3200 km SMF-28 with EDFA-only amplification, and an NS-N-WDM terabit superchannel can transmit over a maximum of 2800 km SMF-28 with EDFA-only amplification. Assuming different coding gain, 11 x 112 Gbit/s per channel with hard-decision (HD) forward-error correction (FEC) and 11 × 128 Gbit/s per channel NS-N-WDM transmission with soft-decision (SD) FEC can be achieved over a maximum of 2100 km and 2170 km, respectively. These are almost equal and were achieved using digital noise filtering and one-bit maximum likelihood sequence estimation (MLSE) at the receiver DSP. Characteristics including the back-to-back (BTB) curves, the ADC bandwidth requirement, and the tolerance to unequal subchannel power of an NS-N-WDM superchannel were also evaluated.