Stochastic Properties and Outage in Crosstalk-Impaired OOK-DD Weakly-Coupled MCF Applications With Low and High Skew×Bit-Rate

Intercore crosstalk (ICXT) impaired weakly-coupled multicore fiber (MCF) systems using on-off keying (OOK) and direct-detection (DD) are experimentally assessed. The stochastic properties of the received bit amplitudes that depend on the relative propagation delay (skew) between two cores of the MCF and on the OOK bit-rate are discussed. For low skew×bit-rate (<; <; 1): (i) the received amplitude of bits 0 or 1 of the interfered core are mainly characterized by two possible levels; (ii) when the short-term average crosstalk (STAXT) power increases (decreases), the fluctuations of the received amplitudes of bits 1 and 0 become larger (lower). For high skew×bit-rate (>>1): (i) the received amplitudes of bits 0 and 1 present a noise-like behaviour; (ii) larger fluctuations of the received amplitudes of the OOK signal may not occur only for high STAXT powers. For both low and high skew×bit-rate, it is shown that the histogram of the received amplitudes of bits 1 or 0, and the histogram of the mean and variance of these amplitudes are reasonably well characterized by Gaussian distributions. Experimental results suggest that the rule of thumb to design emerging MCF applications with higher ICXT tolerance is to use cores with skew much longer than the symbol period.