High-frequency chaotic bursts in laser diode with optical-feedback

The diversity of observed nonlinear dynamics in laser diodes subjected to optical feedback shows promise as an excellent candidate for chaos-based commercial applications. Thus, works in the last decade have primarily focused on system performances, geometric configurations, and balancing their trade-offs. We demonstrate an optical feedback system operating on phase-conjugate feedback exhibiting state-of-the-art chaos bandwidth values reaching approximate to 30 GHz. We report numerous high-frequency, spatiotemporally complex, chaotic dynamics undocumented in the past four decades. We highlight the underlying physics involving a three-tier temporal interaction mechanism between laser relaxation oscillations, phase-conjugate feedback induced external cavity modes, and chaotic bursts repeating each delay time in the extended cavity. We show supporting real-time high-definition system outputs captured by modern large bandwidth oscilloscopes. The presented work shows to our knowledge, the highest bandwidth and complexity entropy to-date in an optical chaos from a single laser, thereby proving the unnecessary need for further complexity using cascading lasers. The chaotic behavior due to the non-linearity present in a time-delayed feedback system has potential applications for secure optical communication and encryption. Here, a laser diode with phase-conjugate feedback is reported with state-of-the-art broadband, spatiotemporally complex, and high-entropy chaos.