DV-QKD in coexistence with classical channels in multicore fiber

The simulation results demonstrate the possibility of simultaneous transmission of the classical and quantum channels in the same multicore fiber using space division multiplexing. Low crosstalk between the fiber cores helps to isolate the T12 DV-QKD channel (that propagates in one of the fiber cores) from the detrimental effect of the spontaneous Raman scattering of the classical channels propagating in both directions in each other core. The simulation illustrates how QBER and secret key rate degrade with an increase of the classical channel power for the specified crosstalk level between the fiber cores. The simulations examine the system over a wide range of classical channel powers (which may exceed typical values) to find an upper bound under which secure communication is still possible.