We show that the performance of a 1310-nm quantum key distribution (QKD) system with an up-conversion detector pumped at 1550 nm is comparable with or better than that of current 1550-nm QKD systems with 1310-nm pump detectors. The nonlinearly induced dark counts are reduced when the wavelength of the pump light is longer than that of the quantum signal. We developed a 1550-nm pump up-conversion detector for a 1310-nm QKD system. We experimentally studied the polarization sensitivity, pump signal format, and various influences on the dark count rate. Using this detector in a proof-of-principle experiment, we achieved a secure key rate of 500 kbit/s at 10 km and 9.1 kbit/s at 50 km in a 625-Mbit/s, B92, polarization-coding QKD system with mean photon number of 0.1, and we expect that the system performance could be improved further if one applies more advanced protocols, higher data rates, and a better periodically poled lithium niobate (PPLN) module.
Citation: Optics Express
Pub Type: Journals
fiber optics communications, optical communications, photon counting, quantum cryptography, quantum detectors