Delayed Optoelectronic and Delayed Incoherent Feedback Lasers

摘要

This report results from a contract tasking Universite Libre de Bruxelles as follows: Lasers are ubiquitous today, mostly in the form of semiconductor lasers (SLs), which are characterized by smallness in size, weight, cost of production, and power requirements. Optical networks depend on SLs for generation, amplification, and distribution of the light that transmits voice, video, and data. However, an unfortunate property of these devices is their high susceptibility to unavoidable optical feedback, such as reflection from any optical element of the system surrounding the laser. Even tiny amounts of optical feedback (less than 0.01%) can cause the laser to enter a state of erratic pulsating instabilities and irregular chaotic transitions. Systematic experimental studies started recently. Fourier spectra measurements showed the gradual emergence of new frequencies as the feedback rate is progressively increased. But time series are still delicate to obtain because of the extremely small time scale of the intensity pulsations. Most of our understanding of these instabilities came from numerical simulations of simple model DDEs where the delay is the round-trip time of the light from the laser to the mirror and back to the laser. We propose to investigate the bifurcation possibilities of these lasers by combined analytical and numerical techniques. The goal is to find simple guidelines on the properties of the pulsating solutions and/or frequencies. The properties of several types of feedback will be compared. Finally, we shall investigate the case of two mutually injected lasers because of a series of experiments studied at Kirtland AFB.