We demonstrate quantum key distribution (QKD) with classical signals in a seven-core fiber using dense wavelength division multiplexing. Quantum signals are transmitted in an outer core separately and intercore crosstalk (IC-XT) is the main impairment of them. In order to alleviate IC-XT, we propose a quantum-classical interleave scheme. Then the properties of IC-XT are analyzed based on the measurement results which indicate counter-propagation is a better co-existence method than co-propagation. Finally, we perform QKD experiments in the presence of two classical channels with a channel spacing of 100 GHz between quantum channel and the nearest classical channels. The experiment results prove counter-propagation almost immune to IC-XT, which is consistent with our analysis. Also, the feasibility of the transmission over the range of metropolitan area networks is validated with our scheme.
@article{arxiv.1811.04198,
title = {Experimental wavelength-space division multiplexing of quantum key distribution with classical optical communication over multicore fiber},
author = {Chun Cai and Yongmei Sun and Yongrui Zhang and Peng Zhang and Jianing Niu and Yuefeng Ji},
journal= {arXiv preprint arXiv:1811.04198},
year = {2019}
}