Impact of spontaneous Raman scattering on quantum channel wavelength-multiplexed with classical channel in time domain

In the quantum key distribution system,quantum channel is always affected by spontaneous Raman scattering noise when it transmits with classical channels that act as synchronization and data channels on a shared fiber. To study the effect of the noise exactly,the temporal distribution characteristics of the Raman scattering noise are analyzed theoretically and measured by a single-photon detector. On the basis of this,a scheme to decrease the noise is proposed.