Fig. 1. Schematic diagram of satellite-to-ground chaotic free-space optical communication system

Fig. 2. Schematic for the free-space optical communication system based on the chaotic pulse position modulation transceiver^[26]

Fig. 3. Architecture of the proposed chaotic free-space optical communication system^[32]

Fig. 4. Optical subsystem before (a) and after (b) introducing the DOEs^[30]

Fig. 5. Configuration of secure data transmission with semiconductor lasers as Tx and Rx. The chaos synchronization between Tx and Rx is implemented in virtue of the symmetric injection from a common driving signal^[27]

Fig. 6. Optoelectronic-feedback-based space-to-ground chaotic laser communication system^[29]

Fig. 7. Chaotic free-space optical communication model^[34]