We present a fully automated quantum key distribution prototype running at 625 MHz clock rate. Taking advantage of ultra low loss (ULL) fibres and low-noise superconducting detectors, we can distribute 6,000 secret bits per second over 100 km and 15 bits per second over 250km.

Quantum confined nanocrystals of PbS in glass were used as intracavity saturable absorbers to obtain passive continuous-wave mode locking in a Cr:forsterite laser. We obtained near transformed-limited 4.6 ps laser pulses at 110 MHz repetition rate, and a wide tunability range of 1207–1307 nm. The absorption saturation intensity of the quantum-dot PbS doped glasses was measured to be 0.2 MW/cm2.

Abstract:We demonstrate mode-division multiplexed WDM transmission over 50-km of few-mode fiber using the fiber's LP 01 and two degenerate LP 11 modes. A few-mode EDFA is used to boost the power of the output signal before a few-mode coherent receiver. A 6×6 time-domain MIMO equalizer is used to recover the transmitted data. We also experimentally characterize the 50-km few-mode fiber and the few-mode EDFA.

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