Experimental investigation of heterodyne quantum key distribution in the S-band or L-band embedded in a commercial C-band DWDM system.

The tolerance of continuous-variable quantum key distribution to co-propagating DWDM channels is investigated. The quantum channel is operated in the S-band or L-band and multiplexed with a commercial C-band DWDM system. The results show that, compared to previously proposed configurations, the number of co-propagating channels can be doubled. At a fiber length of 25 km, 56 DWDM channels with a total launch power of 14.5 dBm are tolerated by the quantum channel.