Outage Probability Due to Intercore Crosstalk in Dual-Core Fiber Links With Direct-Detection

Abstract

The outage probability (OP) in short-haul directdetection (DD) optical links supported by weakly-coupled multicore fiber (MCF) impaired by intercore crosstalk (ICXT) and using on-off keying signaling is assessed theoretically and through simulation. A closed-form expression for the OP is proposed for a single interfering core. This expression is useful to provide fast and reliable performance estimates in preliminary studies of weakly-coupled MCF-based systems where the ICXT is highly correlated along the signal bandwidth, i. e., when the skew-bit rate product is small. Particularly, results for a 20 kmlong link at 10 Gbit/s and walk-off below 1 ps/km are detailed. For high skew-bit rate products, i. e., when the ICXT is decorrelated along the signal bandwidth, simulation results show that, for a typical OP of 10 −4 , the tolerance to ICXT increases above 4 dB, when compared with low skew-bit rate products. It is also shown that DD links with finite extinction ratio are more robust to outage induced by the ICXT than those with ideal extinction ratio.

Carrier Beating Impairment in Weakly Coupled Multicore Fiber-Based IM/DD Systems

“…It can be concluded that the walk-off has no influence on the CBI, because the walk-off has no effect on the characteristics of A XT ,x in (2). This seemingly contradicts the conclusion in [20], which states that significantly different IM/DD system performance can be observed for low and high walk-offs. The reason is that the OC-SXT term is the main XT component in [20] because the same OC's optical frequency of the lasers.…”

“…This seemingly contradicts the conclusion in [20], which states that significantly different IM/DD system performance can be observed for low and high walk-offs. The reason is that the OC-SXT term is the main XT component in [20] because the same OC's optical frequency of the lasers. But the OC-OCXT term is dominant XT component in Fig.…”

“…For short-reach IM/DD systems, many types of homogeneous [15]- [17] or heterogeneous [18] WC-MCF have been optimized with different XT threshold. For different kinds of WC-MCF based systems, the XT threshold has been studied, such as adaptive direction-detection orthogonal frequencydivision multiplexing (DD-OFDM) signals [19], the on-off key (OOK) signal [20], [21], the 4-level pulse amplitude modulation (PAM-4) signal [22] and the PAM-8 signal [23]. The combined effect of laser phase noise and intercore XT on IM/DD systems has also been investigated [24], [25].…”

Outage Probability Due to Crosstalk from Multiple Interfering Cores in PAM4 Inter-Datacenter Connections

“…The DP-DCM has been developed to keep the complexity and time of simulation of ICXT at acceptable levels. In such a model, the evolution of the ICXT impact on the system performance is evaluated in time fractions with a much shorter duration than the ICXT decorrelation time [20]. Those time fractions are separated by time intervals longer than the decorrelation time of ICXT.…”

“…Therefore, the evaluation of the system outage, through the outage probability (OP) metric, is of utmost importance to assess the performance of IM-DD links supported by MCFs. The ICXT impact on the OOK system performance has been assessed by comparing experimental and simulated BERs and OPs in weakly-coupled MCFs [19] and by comparison with theoretical results [20]. The dependence of the OP due to ICXT on several parameters and features of OOK systems, such as the laser linewidth [21], skew-symbol rate product [21,22], and ICXT level [19,22] has been studied.…”