Nonlinear Dynamics of Discrete Mode Semiconductor Lasers with Optical Feedback

Abstract

Research on discrete-mode semiconductor lasers (DMSLs) has revealed interesting insights into how they work fundamentally and operate. This study looked closer at a DMSL to understand its behavior when optical feedback is applied, in order to uncover the nonlinear dynamics and phenomena behind the operation of this particular laser. The research presents a comprehensive analysis answering key questions. First, the study characterized DMSL experimentally using cutting-edge tools to find important performance information. The linear fit methodology is used to determine the threshold current. It also looked at how the lasing wavelength and peak power change as the current increases. In addition, it examined the suppression of side peaks using optical spectra. The study then experimentally investigated the nonlinear dynamics of DMSL under optical feedback. By closely analyzing time series, power spectrum, and phase portraits, the dynamics were mapped out when varying feedback ratios at both bias currents (30, and 40 mA). Remarkably, different dynamic states emerged at specific feedback ratios, including stable state, quasi-periodic, multi-state intermittency, and chaotic. Notably, the shift from stable to quasi-periodic happened at different feedback ratios for each bias current. Multi-state intermittency behavior with combinations of stable state, P1, and quasi-periodic also occurred at particular currents. Intriguingly, chaos appeared at distinct feedback ratios for each current. This study is significant because the knowledge gained can enable innovation in areas such as secure communications and random number generation.