Dresden 2014 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 84: Poster: Electronic structure theory / Carbon (other than graphene) / Si, Ge, and SiC / III-V semiconductors (other than nitrides)
HL 84.15: Poster
Mittwoch, 2. April 2014, 17:00–20:00, P1
Properties of exciton-polariton gap-solitons in a two-dimensional lattice — •Edgar Cerda-Mendez1, Dimitryi Krizhanovskii2, Sergei Gavrilov3, Klaus Biermann1, Maurice S. Skolnick2, and Paulo Santos1 — 1Paul-Drude-Institut für Festkörperelektronik, Berlin, Germany — 2University of Sheffield, Sheffield, United Kingdom — 3Institute of Solid State Physics, Chernogolovka, Russia
Exciton-polaritons are bosonic quasi-particles that result from the strong coupling of photons and quantum well excitons in a semiconductor microcavity (MC). While the small mass arising from the photonic component allows polaritons to form condensates at low densities and high temperatures, the repulsive excitonic interactions provide a strong nonlinearity. The periodic spatial modulation of the MC creates an artificial band structure with energy gaps and negative dispersion. Due to the nonlinearity, spatially self-localized polariton states, known as gap solitons (GSs), may appear within the energy gaps when the kinetic energy contribution due to localization of polaritons with a negative mass compensates their repulsive interaction energy. In this work, we show that the properties of polariton condensate GSs are well described by a simple variational approach to solve the Gross-Pitaevskii equation. The GSs form in an (Al,Ga)As-based MC where a 2D tunable lattice is created by surface acoustic waves. We calculated the metastable states in the square lattice. The model predicts the observed real and k-space profiles of the GS as well as the dependence of its coherence length and optical threshold power with the lattice amplitude.