Negative Refraction in Atomic Two-Component Media

Abstract

Negative Refraction in Atomic Two-ComponentMedia: In the present thesis we study the feasibility of negative refraction at optical wavelengths and low absorption in gases consisting of two species of atoms. Compared to a single-component system, we expect it to be easier to find candidates for an experimental realization due to less stringent conditions that must be met. The two involved species contribute the electric and the magnetic response, respectively. To obtain a negative refractive index, both responses must be large. Therefore, we optimize the magnetic susceptibility, which typically is considerably smaller than the electric susceptibility, in different systems. Moreover, we investigate a mechanism in so-called closed-loop systems that enhances the magnetic response by a factor of 1, the inverse fine structure constant. Closed-loop configurations are characterized by the fact that the coupling control and probe fields build up a closed interaction loop in the level scheme. We find that the enhancement occurs, as the electric probe field component scatters into the magnetic probe transition. Using the previous results, we calculate the refractive index for several combinations of two realistic level schemes and address the occurring instabilities of the probe field. We obtain a refractive index of n = 6.4 and n = 3.7, respectively, at vanishing absorption for two different systems