Fig. 1. Generation of chaotic laser by semiconductor lasers. (a) Optical feedback; (b) optical injection; (c) optoelectronic feedback

Fig. 2. Generation methods of chaotic laser by optoelectronic oscillator. (a) Intensity type; (b) phase type

Fig. 3. Chaos synchronization with semiconductor lasers. (a) System schematic of chaos synchronization system using master-slave scheme and common-signal-driven scheme; (b) typical scatter plots of laser intensity waveforms in synchronized and desynchronized scenarios; (c) influence of injection strength R_inj and optical frequency detuning Δf on chaos synchronization quality in master-slave scheme^[88]; (d) influence of optical wavelength detuning between response lasers on chaos synchronization quality in common-signal-driven scheme^[83]

Fig. 4. Typical schemes of chaotic-carrier optical communication by using chaotic lasers. (a) Master-slave communication system; (b) common-signal-driven communication system

Fig. 5. Message encryption methods at transmitting end in chaotic-carrier optical communication. (a) Chaos masking (optical coupling); (b) chaos masking (electro-optical modulation); (c) chaos modulation; (d) chaos shift keying

Fig. 6. Principles of chaos laser key distribution. (a) Key masking exchange; (b) consistent key extraction

Fig. 7. Field test of master-slave communication system based on chaotic semiconductor lasers^[6]. (a) Experimental setup; (b) results of encrypted and decrypted message; (c) optical-communication metropolitan area network in Athens

Fig. 8. Integrated chaotic laser transceiver with optical feedback and its communication results^[8]. (a) Integrated chaotic laser; (b) result of encrypted message; (c) result of decrypted message

Fig. 9. Communication system and results of wideband chaotic transmitter by mutual optical coupling^[101]. (a) Experimental setup; (b) results of transmitter with increased chaos bandwidth by optical mode beating; (c) secure transmission result of QPSK message

Fig. 10. Discrete-mode laser-based broadband chaos synchronization and result of high-speed chaotic-carrier optical communication^[15]. (a) Synchronized chaotic carrier with wide bandwidth of 31.7 GHz; (b) frequency spectrum of encrypted message; (c) optical communication result

Fig. 11. Field test of chaotic-carrier optical communication based on hardware optoelectronic oscillator^[115-116]. (a) Experimental setup; (b) secure transmission results; (c) optical-communication metropolitan area network in Besançon

Fig. 12. Transmission rate improvement of hardware optoelectronic oscillator-based chaotic-carrier optical communication by using high-order signal format^[117]. (a) Eye diagrams and frequency spectra of doubinary code; (b) communication result of doubinary code-based chaos communication

Fig. 13. Chaotic-carrier optical communication based on AI-OEO receiver: scheme and results in master-slave communication system^[17]. (a) Experimental setup; (b) chaotic waveforms of hardware transmitter and AI receiver; (c) communication result

Fig. 14. Chaotic-carrier optical communication based on AI-OEO transceivers: scheme and results in common-signal-driven communication system^[18]. (a) System schematic; (b) communication result

Fig. 15. Chaotic laser-based key distribution using random feedback phase keying. (a) Scheme diagram^[4]; (b) synchronization random keying^[4]; (c) synchronization recovery time^[165]

Fig. 16. Key distribution based on open-loop chaos synchronization. (a) Output-mode keying of FP laser and mode switching time^[9]; (b) experimental setup of wavelength-shift keying of DBR laser, and synchronization recovery time and wavelength switching time of laser^[94]

Fig. 17. Integrated chaotic lasers. (a) Integrated laser with external cavity modularization^[193]; (b) straight waveguide monolithic integrated laser^[200]; (c) heterogeneous hybrid integrated laser^[204]

Fig. 18. Novel lasers. (a) Short-cavity DFB laser; (b) broadband chaotic output spectrum of short-cavity DFB laser^[206]; (c) 2D microcavity laser^[209]; (d) broadband chaotic output spectrum of 2D microcavity laser^[209]; (e) long-cavity FP laser^[210]; (f) broadband chaotic output spectrum of long-cavity FP laser^[210]