Shared Carrier Phase Recovery of Wavelength- and Space-Division Multiplexed Channels Enabled by CW-Seeded Parametric Optical Frequency Combs

We demonstrate a phase-coherent transmission system supported by the transmission of a seed lightwave in a dedicated multi-core fiber (MCF) core used as a reference for parametric optical frequency comb (OFC) generation at both the transmitter and receiver. We exploit the phase coherence of the wavelength/space-division multiplexed channels to implement a shared digital signal processing (DSP) scheme that reduces the complexity of carrier phase recovery (CPR). In the scheme, the carrier phase noise estimated from a small set of reference channels is used to recover other channels across both wavelengths and cores. The system performance is evaluated over transmission distances of up to 176 km in a 4-core MCF, showing that just 6 reference channels enable CPR of 3 (cores)x150x24-GBaud polarization-multiplexed 64-ary quadrature amplitude modulation C-band channels, with data-rates >30 Tb/s/core. This is achieved with <0.5 dB Q-factor compared to independent CPR. The results demonstrate the potential of OFC-based MCF systems for high-capacity, short- to medium-reach optical interconnects with reduced hardware requirements and simplified DSP.