Doubling direct-detection data rate by polarization multiplexing of 16-QAM without a polarization controller

Polarization multiplexing (POL-MUX) is precluded in self-coherent direct-detection (DD) with remotely transmitted pilot, as signal x pilot components fade. We propose POL-MUX QAM by novel low-complexity photonic integrated optical front-end and adaptive 3×2 MIMO DSP.