DAC-free generation and 320-km transmission of 11.2-GBd PDM-64QAM using a single I/Q modulator

We successfully generate 11.2-GBd PDM-64QAM using one I/Q modulator driven with eight-level signals synthesized by all binary electrical inputs. The signal quality is verified with ~1-dB Q margin (from 7% FEC threshold) after 320-km SSMF transmission.