Monolithic Polarization and Phase Diversity Coherent Receiver in Silicon

In this paper, we realized a monolithic silicon photonic integrated circuit (PIC) for polarization and phase diversity coherent detection. The PIC includes two polarization beam splitters, two 90 $^{\circ}$ optical hybrids, and four pairs of balanced photodiodes implemented as integrated germanium detectors. We tested the PIC using polarization-division multiplexed quadrature phase-shift keyed signals at 43 and at 112 Gb/s.