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2017-08-30 - Article/Dans un journal avec peer-review - Anglais - 9 page(s)

Rivolta Nicolas , Benisty Henri, Maes Bjorn , "Topological edge modes with PT symmetry in a quasi-periodic structure" in Physical Review A, 96, 2, 023864, 10.1103/PhysRevA.96.023864

  • Edition : American Physical Society
  • Codes CREF : Matériaux optiques (DI1256)
  • Unités de recherche UMONS : Matériaux Micro et Nanophotoniques (S803)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)
  • Centres UMONS : Physique des matériaux (CRPM)

Abstract(s) :

(Anglais) We investigate topological features of a 1D photonic quasi-crystal within the PT symmetry context. Via the scattering characteristics we analyze various properties of a particular mirrored structure, which supports topological edge modes in its bandgaps. These interface modes display a non-trivial dependence on the quasi-periodic geometry, even in a passive system. Subsequently, the tailored addition of gain and loss generates curious PT-like features. For example, the quasi-crystal high density of modes leads to complicated mode-merging behaviours between edge and band modes, such as the symmetry recovery phenomenon. Furthermore, anisotropic transmission resonances (connected with unidirectional invisibility) are also present, but they display richer patterns in comparison to previously studied periodic structures. Additionally, we examine lasing effects in detail, with numerics and a simple Fabry-Perot model. The large variety of mode-merging behaviours opens the way to laser resonance engineering.