Joint classical and quantum optical communications

An optical communication method via an optical propagation medium, comprising

• modulating an optical carrier by both a first electrical signal and a second electrical signal, in order to provide an optical dual signal comprising an optical quantum signal resulting from the modulation of the optical carrier by the first electrical signal and an optical classical signal resulting from the modulation of the optical carrier by the second signal, first data being encoded in the first electrical signal;
• transmitting the dual optical signal on the optical propagation medium;
• receiving the dual optical signal from the optical propagation medium (120);
• extracting the first electrical signal and the second electrical signal (RFc) from the received dual signal using a coherent receiver comprising a local oscillator;
• compensating in the extracted first signal and from the extracted second signal
• a frequency mismatch between a central frequency of the optical quantum signal and a local oscillator optical wave provided by the local oscillator;
• and/or
• a phase mismatch between the optical carrier and the local oscillator wave;
• and
• decoding the first data from the compensated first signal;
• wherein second data are encoded in the electrical second signal and wherein the method further comprises:
• decoding the second data from the extracted second signal.