Abstract
A theoretical model for the stochastic time evolution of the intercore crosstalk (ICXT) in homogeneous weakly-coupled multicore fibers (MCF) with multiple interfering cores is proposed and validated experimentally. The model relies on the introduction of non-stationary time varying random phase shifts at every center point between the phase matching points of the MCF where the difference of the effective refractive indexes of the core of the originating signal and the core suffering from ICXT is zero. Closed form-expressions for the autocovariance of the short-term average ICXT (STAXT) with stationary and non-stationary phase shift models in MCFs with multiple excited cores are derived and validated by comparison with experimental results. These expressions enable estimating the decorrelation time of the STAXT generated by multiple interfering cores from the decorrelation times of the STAXT generated by each pair of cores. The proposed model and the ICXT measurements taken continuously over more than 150 hours show that the decorrelation time of the STAXT generated by multiple interfering cores exceeds the one obtained for the pair of cores with shorter decorrelation time. The proposed model is increasingly important to simulate and design MCF-based systems where the ICXT dynamics must be properly accounted for to develop efficient ICXT-tolerant techniques.
Highlights
Multicore fiber (MCF) technology is a powerful candidate to overcome the capacity crunch foreseen for the near future in different optical networks
The short-term average ICXT (STAXT) autocovariance evaluated from experimental measurements is obtained and compared with the STAXT autocovariance proposed in Eq (17) for a MCF with multiple interfering cores
We conceive that the inconsistency may result from (i) some inaccuracy of the experimental measurements, (ii) due to its simplicity, the model proposed is unable to completely characterize the mechanism associated with the random time variation of the ICXT in MCFs leading to some inaccuracy in the tails of the autocovariance of the STAXT and (iii) the contribution of the crosstalk induced by the fan-in and fan-out devices to the autocovariance of the STAXT may not be neglected in the tail region
Summary
Multicore fiber (MCF) technology is a powerful candidate to overcome the capacity crunch foreseen for the near future in different optical networks. In [29], the random time nature of the ICXT and STAXT in weakly-coupled homogeneous MCFs have been theoretically modeled by including a stochastic time variation in each phase shift. A Brownian motion has been proposed to model the time evolution of the phase shifts, and closed form expressions for the autocorrelation and autocovariance functions of the STAXT have been proposed With this model, derived considering only one interfering core, simulation of the time varying nature of the ICXT in MCFs can be performed. From these results, the parameters required by the theoretical model to evaluate the autocovariance of the STAXT are estimated and the autocovariance of the STAXT evaluated from the proposed model with multiple interfering cores is validated.
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