Fig. 1. Block diagram of the OEO chaotic system with double feedback

Fig. 2. (a) Time-domain diagram of the OEO chaotic system with single feedback; (b) detail for Fig. 2(a)

Fig. 3. Time-domain diagram of the OEO chaotic system with double feedback; (b) detail for Fig. 3(a)

Fig. 4. Chaotic bifurcation diagrams of (a) single feedback OEOchaotic system and (b) double feedback OEO chaotic system

Fig. 5. Variation of power spectrum and autocorrelogram under different combinations of delay time T1 and T2. (a) Power spectrum; (b) autocorrelogram

Fig. 6. Evolution of time-delay signature of the original OEO, double delay OEO and variable parameter OEO with the gain

Fig. 7. Comparison of permutation entropy of the original OEO, double delay OEO and variable parameters OEO

Fig. 8. Evolution of the permutation entropy of the double-delay chaotic laser system with different combinations of two delay time

Fig. 9. Evolution of the entropy of the double-delay chaotic laser system with different combinations of two gains