High-speed secure key distribution using local polarization modulation driven by optical chaos in reciprocal fiber channel.

We propose a secure key distribution (SKD) based on local polarization modulation driven by optical chaos in a reciprocal fiber link. A robust error-free SKD with a key generation rate of 4.3 Gbit/s over transmission of 10-km standard single-mode fiber is experimentally demonstrated. A chaotic laser system shared by legitimate users serves as an external wideband entropy source. The polarization reciprocity of the fiber channel provides fundamental safety against eavesdropping. The robustness of SKD resulted from local chaotic polarization modulation is also theoretically analyzed and then verified by practical performance. The proposed scheme is an alternative SKD strategy with high speed and strong security.