Experimental Investigation of Crosstalk Penalties in Multicore Fiber Transmission Systems

We experimentally study the impact of crosstalk in multicore fibers, using polarization-multiplexed quadrature phase-shift keying signals. Using a 7-core fiber, we perform single-span transmission experiments, where the level of crosstalk to the core under test can be varied. We find the penalty in the required optical signal-to-noise ratio (OSNR), compared to a system with no crosstalk, for different signal-to-crosstalk ratios and at different pre-forward-error-correction target bit-error rates (BERs). We show that, for a 1-dB penalty, a 15.7-dB signal-to-crosstalk ratio can be tolerated at BER = 1 × 10^-3. We also perform recirculating loop experiments with varying amount of crosstalk per span to find the impact on the achievable transmission distance.