All-Optical MIMO Demultiplexing Using Silicon-Photonic Dual-Polarization Optical Unitary Processor

Dual-polarization (DP) arbitrary optical unitary processor (OUP) is a critical device to realize an energy-efficient multi-input-multi-output (MIMO) process of mode-division multiplexed (MDM) systems in the optical domain. In this article, a 6-port OUP with polarization-splitter-rotators is realized on a compact silicon photonic chip based on the multi-plane light conversion (MPLC) concept. All-optical MIMO demultiplexing of 300-Gbps 3-mode DP quadrature phase-shift-keying (QPSK) signal is demonstrated at 1540, 1550, and 1560-nm wavelengths with an energy consumption of around 1.5 pJ/bit. Since all-optical MIMO is transparent to the signal format, the energy cost (J/bit) would decrease inversely as we increase the baudrate, making it an attractive approach in reducing the power consumption of the future ultra-high-capacity MDM systems.