8 $\times$ 448-Gb/s WDM Transmission of 56-GBd PDM 16-QAM OTDM Signals Over 250-km Ultralarge Effective Area Fiber

An 8 × 448-Gb/s polarization-division-multiplexing 16-ary quadrature amplitude modulation wavelength-division multiplexing signal with 4-b/s/Hz spectral efficiency is generated using optical time-division multiplexing and real-time field-programmable gate array-based generation of four-level in-phase and quadrature modulator driving signals. Transmission performance over 250-km ultralarge effective area fiber with erbium-doped fiber amplifier-only amplification is investigated.