## 4 Conclusions  
In this work, the impact of ICXT on the OP of 112 Gb/s PAM4 signals in inter-DCI links links with full loss and dispersion compensation has been studied through MC simulation.  
It has been shown that, for one interfering core and high SSRP, the system is more tolerant to the ICXT than for low SSRP, with an improved tolerance of around 8 dB. The OP has been assessed by setting the ICXT level independent from the MCF length and considering the variation of the MCF length from 10 km, where electrical noise significantly contributes to the performance degradation, to 80 km, where signal-ASE beat noise is dominant. With the increase of the MCF length from 10 km to 80 km, the maximum acceptable ICXT level for an OP = \(10^{-4}\) varies only 1.4 and less than 0.5 dB, respectively, for \(|S_{mn}\cdot R_{s}|\) = 1000 and \(|S_{mn}\cdot R_{s}|\) = 0.01.  
The OP dependence on the number of interfering cores has been also studied. It has been shown that, by doubling the number of interfering cores, the maximum acceptable ICXT level per interfering core to not exceed OP = \(10^{-4}\) decreases nearly 3 dB and 3.5 dB, for \(r=0\) and \(r=0.1\), respectively, and independently of the SSRP regime. In addition, it has been shown that, for high SSRP, an extinction ratio of 0.1 tolerates a higher ICXT level of about 6 dB in comparison with null extinction ratio, while, for low SSRP, the ICXT tolerance is not significantly affected by the extinction ratio variation. Furthermore, having two interfering cores with different SSRPs leads to an intermediate situation regarding the  
Figure 5: OP as a function of the ICXT level per interfering core, for \(L\) = 80 km, for two interfering cores, with the same SSRP and with different SSRPs, for (**a**) \(r=0\) and (**b**) \(r=0.1\). The dashed lines represent a cubic interpolation of log\({}_{10}\)(OP).  
maximum acceptable ICXT level to achieve an OP of \(10^{-4}\), in comparison to having both cores with high SSRP or low SSRP. Therefore, having one core with low SSRP is enough to induce a severe reduction of the maximum acceptable ICXT level for a specific OP, even if the other interfering cores have a small contribution to ICXT, as in the case of high SSRP.  
The results presented in this work have been obtained through numerical simulation only and considered some simplifications. In an experimental environment, the OP levels presented in this work may be affected when, considering different values for some relevant system features such as spatial MUX, DeMUX, and optical filter insertion losses, ICXT in the spatial MUX and DeMUX, differences between the chromatic dispersion parameters of the different cores, different losses in each core, and incomplete dispersion compensation (resulting in significant residual dispersion).  
Conceptualization, J.R. and A.C.; Data curation, R.D., J.R., and A.C.; Formal analysis, J.R. and A.C.; Investigation, R.D., J.R., and A.C.; Methodology, J.R. and A.C.; Project administration, J.R. and A.C.; Software, R.D. and J.R.; Supervision, J.R. and A.C.; Validation, J.R. and A.C.; Visualization, R.D., J.R., and A.C.; Writing--original draft, R.D.; Writing--review and editing, R.D., J.R., and A.C. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
This work is supported by FCT/MCTES and when applicable co-supported under the project UIDB/EEA/50008/2020 and project DigCore/UIDP/50008/2020.  
The authors declare no conflict of interest.