Reduction of FWM noise in WDM-based QKD systems using interleaved and unequally spaced channels

Abstract

To extensively deploy quantum key distribution (QKD) systems, copropagating with classical channels on the same fiber using wavelength division multiplexing (WDM) technology becomes a critical issue. We propose a user-based channel-interleaving WDM scheme with unequal frequency spacing (UFS-iWDM) to reduce the impairment on the quantum channels induced by four-wave mixing (FWM), and theoretically analyze its impact on quantum bit error rate (QBER). Numerical simulation results show that a UFS-iWDM can significantly reduce the FWM noise and improve QBER compared with the corresponding WDM scheme with equal frequency spacing (EFS), especially in the case of nonzero dispersion shifted fiber.