Surface plasmons (SPs) are surface waves at the interface between a dielectric and a good metal, and are formed by the interaction between light and the free electrons at the metal-dielectric... Show moreSurface plasmons (SPs) are surface waves at the interface between a dielectric and a good metal, and are formed by the interaction between light and the free electrons at the metal-dielectric interface. They provide strong field confinement for optical fields, opening new possibilities for enhanced light-matter interaction. We combine SPs with a semiconductor gain layer and a resonator for SPs to create a SP-laser. The resonator for SPs is created by scattering on an array of holes in the gold film, i.e., a metal hole array. In this thesis, we describe experiments on SP propagation and SP lasing in active two-dimensional metal hole arrays operating at telecom wavelengths. A resonator for SPs is created by scattering on an array of holes in the gold film. We have studied such active hole arrays with square and hexagonal lattice symmetries both below and above their lasing threshold. We have investigated the role of the symmetry of the lattice on the SP propagation and SP lasing. We have explored the laser frequencies and the feedback mechanism of these SP lasers, and observed the spatial profile and direction of the emitted laser beams. Show less
Stochastic differential equations with delay are the inspiration for this thesis. Examples of such equations arise in population models, control systems with delay and noise, lasers, economical... Show moreStochastic differential equations with delay are the inspiration for this thesis. Examples of such equations arise in population models, control systems with delay and noise, lasers, economical models, neural networks, environmental pollution and in many other situations. In such models we are often interested in the evolution of a particular quantity, for example the size of a population, or the amount of pollution in a particular area, changing in time. A differential equation with delay, or delay equation, is a differential equation in which the change in time of such a quantity is expressed as a function of the value of that quantity at different points in time, in the past as well as in the present. This is in contrast with an ordinary differential equation, in which the change in time of the quantity at a specific time is expressed as a function of that quantity at that specific time only. Show less
