We demonstrate the first 10GHz clock-rate, differential-phase-shift-keyed quantum key distribution system on a 10Gb/s multi-user WDM-PON network. A dual feeder fiber scheme is used to reduce spontaneous Raman scattering-induced inter-channel cross-talk.
We present the first demonstration of quantum key distribution (QKD) on a multi-user wavelength division multiplexed passive optical network (WDM-PON) with simultaneous, bidirectional 10Gb/s classical channel transmission. The C-Band QKD system operates at a clock rate of 10GHz and employs differential phase shift keying (DPSK). A dual feeder fiber and band filtering scheme is used to suppress classical to quantum channel cross-talk generated by spontaneous Raman scattering, which would otherwise prevent secure key distribution. Quantum keys were distributed to 4 users with negligible Raman cross-talk penalties. The mean QBER value for 4 users was 3.5% with a mean raw key distribution rate of 1.3Mb/s, which decreased to 696kb/s after temporal windowing to reduce inter-symbol interference due to single photon detector timing jitter.
To improve the potential security threats of WDM-PON access network, a novel WDM-PON based on quantum key distribution FPGA controller of passive decoy state modified model is presented here. QKD FPGA is responsible for 1.25 Gbps upstream PRBS source, clock regeneration, phase modulation control, key sifting, privacy amplification, and upstream time-divided-multiple-access control on quantum channels. An 8-user network experiment shows that over 20 km fibre, the mean secure exchange key rate can reach up to 500 bps in total, with the acceptable quantum bit error rate below safe limit and a few impact on classical channels. This scheme can provide a promising way for the coexistence between quantum key distribution and classical data service.
To improve the potential security threats of WDM-PON access network, a novel WDM-PON based on quantum key distribution FPGA controller of passive decoy state modified model is presented here. QKD FPGA is responsible for 1.25 Gbps upstream PRBS source, clock regeneration, phase modulation control, key sifting, privacy amplification, and upstream time-divided-multiple-access control on quantum channels. An 8-user network experiment shows that over 20 km fibre, the mean secure exchange key rate can reach up to 500 bps in total, with the acceptable quantum bit error rate below safe limit and a few impact on classical channels. This scheme can provide a promising way for the coexistence between quantum key distribution and classical data service.
The integration of quantum key distribution (QKD) into passive optical networks (PONs) poses new challenges due to the specific characteristics of the access network, as the high losses from passive splitters and the spontaneous Raman scattering noise generated by classical channels co-propagating in the same optical fiber. In this paper, different QKD technologies and implementations are compared, taking into account both discrete-variable and continuous-variable QKD systems to maximize the achievable secret key rate performance in single-fiber bidirectional PONs.
This paper reports the first quantum key distribution experiment implemented with a 10-GHz clock frequency. We used a 10-GHz actively mode-locked fiber laser as a source of short coherent pulses and single photon detectors based on frequency up-conversion in periodically poled lithium niobate waveguides. The use of short pulses and low-jitter upconversion detectors significantly reduced the bit errors caused by detector dark counts even after long-distance transmission of a weak coherent state pulse. We employed the differential phase shift quantum key distribution protocol, and generated sifted keys at a rate of 3.7 kbit/s over a 105 km fiber with a bit error rate of 9.7%.