Coherent detection-based high-speed chaotic secure transmission method

A coherent detection-based high-speed chaotic secure transmission method, comprising the following steps:

• step 1:
• at a transmit terminal in a chaotic secure transmission system, optically coupling an optical chaotic carrier c(t) and transmission information m(t) by using an orthogonal basis, masking the transmission information by using a noise feature of the optical chaotic carrier to obtain a chaotic masked signal cm(t);
• wherein the orthogonal basis comprises at least one of a polarization orthogonal basis or a phase orthogonal basis;
• step 2:
• transmitting the chaotic masked signal over an optical fiber transmission link;
• and
• step 3:
• at a receive terminal in the chaotic secure transmission system, compensating the chaotic masked signal after coherent detection for linear and nonlinear effects through digital signal processing and using a phase orthogonal basis-based chaotic decryption algorithm to separate the optical chaotic carrier from the chaotic masked signal so as to complete decryption,
• wherein using the phase orthogonal basis-based chaotic decryption algorithm to decrypt the chaotic masked signal obtained by optically coupling the optical chaotic carrier c(t) and the transmission information m(t) by using the phase orthogonal basis is specifically implemented as follows:
• (1) first compensating the chaotic masked signal received by the receive terminal for the linear and nonlinear effects to obtain a compensated chaotic masked signal, wherein the compensated chaotic masked signal is represented by Einp;
• then performing distributed Fourier transform on the compensated chaotic masked signal Einp to obtain spectrum information of the compensated chaotic masked signal and searching for a maximum peak of the spectrum information to obtain initial frequency offset information fc of the compensated chaotic masked signal;
• and finally, performing initial frequency offset compensation to obtain a signal Einc;
• and
• (2) performing serial-to-parallel conversion on the signal Einc after the initial frequency offset compensation to obtain a series of parallel data, and testing a phase slope lf of the series of parallel data to further estimate an accurate frequency offset of the signal, so as to implement accurate frequency offset compensation of the signal;
• using an average information phase of parallel data having signal intensity greater than a threshold Rth to compensate for a laser phase noise disturbance;
• and obtaining the transmission information through in-phase and quadrature (IQ) separation after the compensation to implement chaotic decryption.