title: Toy model for plasmonic metamaterial resonances coupled to two-level system gain.
abstract: We propose, solve, and discuss a simple model for a metamaterial incorporating optical gain: A single bosonic resonance is coupled to a fermionic (inverted) two-level-system resonance via local-field interactions. For given steady-state inversion, this model can be solved analytically, revealing a rich variety of (Fano) absorption/gain lineshapes. We also give an analytic expression for the fixed inversion resulting from gain pinning under steady-state conditions. Furthermore, the dynamic response of the "lasing SPASER", i.e., its relaxation oscillations, can be obtained by simple numerical calculations within the same model. As a result, this toy model can be viewed as the near-field-optical counterpart of the usual LASER rate equations.
authors.affiliation: Institut für Angewandte Physik and DFG-Center for Functional Nanostructures (CFN), Universität Karlsruhe (TH), Wolfgang Gaede-Strasse 1, D-76128 Karlsruhe, Germany. Martin.Wegener@physik.uni-karlsruhe.de
authors.forename: Martin
authors.initials: M
authors.lastname: Wegener
authors.forename: Juan Luis
authors.initials: JL
authors.lastname: García-Pomar
authors.forename: Costas M
authors.initials: CM
authors.lastname: Soukoulis
authors.forename: Nina
authors.initials: N
authors.lastname: Meinzer
authors.forename: Matthias
authors.initials: M
authors.lastname: Ruther
authors.forename: Stefan
authors.initials: S
authors.lastname: Linden