Chaotic Synchronization of Mutually Coupled Lasers with Another Laser and Its Encoding Application in Secret Communication

Abstract A chaotic synchronization based on mutually coupled different semiconductor lasers and its coding communications are studied. A route to chaos is illustrated by a bifurcate diagram. Chaotic distribution is presented in two lasers. The synchronization equation is given in theory. A chaotic synchronization is obtained between the emitter and the receiver. Other complex dynamical behavior synchronizations are also obtained, such as period-5 and period-10 synchronizations. Cascade synchronizations are achieved. A novel On/Off coding system is presented while its chaotic phase encoding is successfully implemented. Chaos key is also numerically simulated. We find that synchronization can still be achieved when the parameter of the emitter changes at any time so that the newly generated chaotic carrier can ensure mask the information in each communication. Then the real-time variable parameter results in difficulty for eavesdroppers to decipher. Compared with a single laser emitter, this emitter has many secret keys and high security, which is beneficial to its potential application in secret communication.