Fig. 1. Schematic of proposed key distribution scheme

Fig. 2. Time series, RF spectra, and cross correlation curve of chaotic driving signal before and after passing through the M-Z interferometer. (a)(c) Time series; (b)(d) RF spectra; (e) cross correlation curve

Fig. 3. Time series and cross correlation curves with and without M-Z interferometer under K_j＝0.2. (a) Time series of DFB-D and DFB-A with or without M-Z interferometer; (b) cross correlation curve of chaotic signals from DFB-D and DFB-A without M-Z interferometer; (c) cross correlation curve of chaotic signals from DFB-D and DFB-A with M-Z interferometer

Fig. 4. Time series and scatter plots of DFB-A and DFB-B. (a)(b) Phase difference Δϕ＝0; (c)(d) phase difference Δϕ＝π

Fig. 5. Phase-shift-keying code and short-time cross correlation curve between DFB-A and DFB-B. (a) Phase-shift-keying code; (b) short-time cross correlation curve

Fig. 6. Probability distribution of chaos synchronization recovery time

Fig. 7. Influence of parameter mismatch on chaos synchronization and bit error rate (BER). Influence of phase parameter mismatch on (a) chaotic synchronization and (b) BER; (c) influence of intrinsic parameter mismatch on chaotic synchronization; influence of intrinsic parameter mismatch on BER under (d) R＝1.0, (e) R＝0.5, and (f) R＝0.2

Fig. 8. BER as a function of retained ratio when eavesdropper intercepts and quantizes the chaotic drive signal from key distribution system with and without M-Z interferometer