Delay Times Extraction In A Chaotic Semiconductor Laser With Double Optical Feedback

In recent years, chaos has attracted much attention for its potential applications in the laser ranging, secure communications, and true random number generator. The main methods of generating chaotic laser with semiconductor are injection, optoelectronic feedback and optical feedback. However, utilizing optical feedback can easily produce broadband high-dimensional chaos in semiconductor laser, which is used as the primary means of generating chaotic source in practical application. But the semiconductor laser with single feedback contains significant periodic signals of external cavity, which will lead to a high side lobe in the laser ranging and be weakly secure systems because of delay time identification. Therefore, in order to eliminate the influence of the external cavity cycle and improve the complexity of chaos, people have been explored to generate chaos in double feedback.Focusing on generating chaotic laser with double feedback, this thesis is mainly summarized as follows:1. The numerical model of laser diodes with double optical feedback built on the rate equation of single feedback. Theoretically we realized the generation of chaotic laser in the semiconductor with double feed back, and found the double feedback compared with single feedback can improve spectrum bandwidth and the spectrum of chaotic laser contain external cavity length information.2. In the experiment we provide a detailed analysis of the power spectrum of dual external cavities of system. Compared to the system of single feedback, the dual feedback produces spectral envelope modulation in the power spectrum. We show that the value of cavity resonance frequencies can be deduced from the power spectra both integer multiple external-cavity lengths and fractional multiple cavity lengths in different feedback strength. So dual-feedback external cavities information can not be hidden, and external cavities with multi-channel feedback can also be deduced from the power spectra.3. Through experiments and theoretical simulation, we analyzed the impact of bias currents and feedback intensity on peak sidelobe and the full width of half of autocorrelation, and studied numerically both bias currents and feedback intensity related to chaotic waveform characterized with the largest lyapunov exponent and correlation dimension.