Experimental demonstration of polarization-division multiplexing of chaotic laser secure communications

Optical polarization-division multiplexing (PDM) can double the capacity of a communication system. In this paper, PDM between a conventional fiber-optic channel and a chaos-encrypted channel, and between two chaos-encrypted channels, is proposed and experimentally investigated. The bit rate for each channel is 1.25 Gb/s, while the transmission in the standard single-mode fiber can be up to 22.54 km. The effect of the mutual power leakages on the receiver quality is experimentally explored, which is induced by the variation in polarization direction during the propagating process. In addition, the effect of optical launched power at the transmitter side on the Q-factor is tested and analyzed.