Fig. 1. Conceptual scenario of private person-to-person THz chaotic communication.

Fig. 2. Schematic of photonic heterodyne generation of encrypted THz signal with physical chaos.

Fig. 3. Principle of NN training and THz chaos synchronization.

Fig. 4. Experimental setup of private THz chaotic communication.

Fig. 5. Photonic THz chaos synchronization performance. (a) NN training performance between physical chaos and chaos from NN with 45-deg line; (b) temporal waveform comparison between physical chaos and chaos from NN; (c) C.C results at Alice’s and Bob’s sides.

Fig. 6. Transmission performance in terms of BER and eye diagram with different mask coefficient (α).

Fig. 7. Data capacities CBob (blue line with hexagon) and CEve (red line with dot) versus the mask coefficient (α).

Fig. 8. Information interception probability (η) of Eve with chaos mismatching time.

Fig. 9. BER performance of Eve with the free ciphertext attack.