Coherent QPSK Signals Based on Channel Noise Coding

Due to the lack of security of traditional optical chaotic communication, we propose a secure QPSK transmission scheme based on chaotic Channel noise. Numerical results show that this scheme can transmit <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$10 ~\text{Gb} / \mathrm{s}$</tex> QPSK signals below the hard decision forward error correction limit, with symbol error rate of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{0. 9 8}$</tex> for eavesdroppers.