Exciton-polariton confinement in Fibonacci quasiperiodic superlattice

Abstract

We investigate the propagation of exciton-polaritons (bulk and surface modes) in quasiperiodic superlattices of Fibonacci type, truncated at z = 0, where z is defined as the growth axis. For our purposes, the Fibonacci structure can be realized experimentally by juxtaposing two basic building blocks A and B, following a Fibonacci sequential rule. Here A is the spatially dispersive medium modelled by a semiconductor from the nitride family (GaN, for instance), which alternates with a common dielectric medium B (sapphire). Our main aim is the investigation of the modified optical properties of the exciton polariton modes for a better understanding of the dynamics of the excitation in confined systems. The dispersion relation shows a bottleneck profile for the superlattice modes, whose behavior is similar to those found in the bulk crystal. The Cantor-like energy spectrum is also investigated, and scaling properties are shown for the Fibonacci quasiperiodic structure.