# Intercore spontaneous Raman scattering impact on quantum key distribution in multicore fber

## TL;DR

This paper models intercore spontaneous Raman scattering in multicore fibers, analyzing its impact on quantum key distribution and comparing it with single-core fiber scattering effects.

## Contribution

It introduces a novel quantitative model for ICSRS based on intercore crosstalk characterization and evaluates its effects on QKD performance.

## Key findings

- Both forward and backward ICSRS reduce maximum transmission distance.
- High classical signal powers in dense WDM systems affect quantum signals.
- ICSRS behavior is similar to SRS in single-core fibers over distance.

## Abstract

We propose a model, for the first time, to quantitatively estimate the intercore spontaneous Raman scattering (ICSRS) in multicore fber (MCF) based on the characterization of intercore crosstalk (ICXT). Also, we show the propertis of ICSRS through numerical simulations. Then the impact of ICSRS on quantum key distribution (QKD) is evaluated. It is revealed that both the forward-ICSRS and backwardICSRS will reduce the maximum transmisson distance and the forward-ICSRS will reduce more. However, over the range of metropolitan area networks, quantum signals are affected only when the powers of classical signals are very high in dense wavelength division multiplexing system. Finally, the spontaneous Raman scattering (SRS) generated in single core fiber and the ICSRS generated in MCF are compared. The power variety trend with the transmission distance of SRS is similar to that of ICSRS, though there are subtle differences.