Study On Time-delay Signature And Bandwidth Of The Chaos Generated By A Vertical-cavity Surface-emitting Laser Under Chaotic Optical Injection

Based on the chaotic signals generated by semiconductor laser has been widely applied in the physical random number generators,chaotic radar,high-speed chaotic secure communications,etc.The optical feedback,optical injection and photoelectric feedback external disturbance all make the semiconductor laser produce chaotic signal,and the optical feedback system is preferred because it is easy to produce the high dimensional chaos,of course,chaotic generated by optical feedback includes recurrence features termed time-delay signature(TDS),The TDS can provide a opportunity for eavesdropper to extract a key parameter,which may break the security of chaotic communications,so how to suppress the TDS of the delay system becomes the hot topic of research;On the other hand,The optical injection system can enhance the bandwidth of chaotic signal and improve the information transmission capacity,and also can suppress the chaotic signal TDS.So comprehensively consideration,injected chaotic output signals of vertical cavity surface emitting laser(VCSEL)with double-optical feedback into another VCSEL,which can obtain two-channel chaotic signals with more suppressed TDS and wider bandwidth.In this thesis,an acquired high-performance chaotic system driven by chaotic optical injection is proposed,in which a vertical-cavity surface-emitting laser(named master VCSEL)subject to double optical feedback is parallelly and unidirectionally injected into another VCSEL(named slave VCSEL),and the effective bandwidth(EBW)and TDS of the chaotic signal obtained by the system are simulated theoretically.Firstly,use the spin flip model rate equation of VCSELs and combine the autocorrelation analysis tool of time-delay system,The results show that the TDS for two orthogonal polarization components of master VCSEL with double optical feedback can be obviously much weaker than those for single optical feedback under the equal feedback strength by selecting suitable feedback delay time,and the average intensity of the two chaotic signals are almost equal,the TDS values are 0.20 and 0.16,respectively.On this basis,by injecting the chaotic outputs from the master VCSEL into the slaver VCSEL,the two polarization components chaotic outputs from the slaver VCSEL can be obtained the simultaneously suppressed TDS and wide bandwidth.Moreover,through further analyzing the influences of the injection strength and frequency detuning on the EBW of the chaotic system,we find that the EBW of the two polarization components of the slaver VCSEL are significantly higher than that for master VCSEL under stronger injection strength and larger frequency detuning conditions.Finally,the chaotic signals of slaver VCSEL with wide EBW and suppressed TDS can be determined by combining the evolution characteristics of TDS and EBW of chaotic outputs in the parameter space of injection strength and frequency detuning.