Research On Time-delay Signature Identiifcation In Chaotic Semiconductor Laser With Optical Feedback Based On Power Spectrum Analysis

External-cavity feedback semiconductor lasers have been used extensively as the firstcandidate of chaotic light source in random key generation, chaotic secure communications,high-resolution lidar ranging and chaotic optical time domain reflectometer, because of simpleconfiguration, good stability and complex dynamics. However, external-cavity resonancemakes chaos has time-delay signature and implicit periodicity, which will reduce the securityof chaotic communication system and degrade the randomness of random number extractedfrom chaos. Therefore, suppression of time delay in chaotic semiconductor laser has becomethe attracted focus in chaos application.In this thesis, firstly, we investigate whether time delay information can be suppressed inedge emitting laser (EEL) with mirror feedback by power spectrum analysis. Then, weexplore the scheme on filtered feedback which time delay can be hidden. The main work andresults are summarized as follows.1) Experimentally and numerically study the time delay extraction in chaotic EEL withmirror optical feedback. By power spectrum analysis, we find time delay information can beidentified for the situation which time delay can be hidden in view of the existing study.However, using autocorrelation function (ACF) and mutual information(MI), identification oftime delay depend on the length of time series. The time delay can be extracted frombackground noise only for enough long timeseries, otherwise can be hidden. So, analysis theenough long time series by ACF and MI, the time delay information also can be extractedfrom the above situation. In addition, the situation is able distinguish between single optical feedback and double optical feedback τ1:τ2≈1:2,FPR1> FPR2by power spectrum analysismethod, unable by ACF and MI. Therefore, for fixed time delay feedback system, time delaycannot be suppressed based on power spectrum analysis.2) We proposed time delay can be hidden in EEL with filtered optical feedback.Numerical simulation analysis the effect of the filter parameters (filter line width of thefrequency detuning amount) and the parameters of the external cavity feedback (feedbackstrength and external cavity length) on time delay identification. Simulation results show thatthe time delay information is more difficult to identify with filtered optical feedback thanmirror optical feedback delay under the same feedback strengthen. The preliminaryexperimental results also confirmed this.3) We proposed also time delay can be hidden in vertical cavity surface emitting laser(VCSEL) with filtered optical feedback. Based on SFM, we established rate equation ofVCSEL with filtered optical feedback. Numerical simulation results show that time delay canbe extracted easily for VCSEL with mirror feedback, while can be hidden for VCSEL withfiltered feedback at the same feedback rate, which choose the appropriate filter parameters(filter line width, frequency detuning). In addition, we analyze the influence of line width andfrequency detuning on the identification of time delay. The results show that the narrower theline width, time delay information more easily be hidden; the frequency of the filter withVCSEL larger mismatch, time delay information can be suppressed.