Emulation of lossless exciton-polariton condensates by dual-core optical waveguides: Stability, collective modes, and dark solitons

Year: 2014

Authors: Salasnich L., Malomed B.A., Toigo F.

Autors Affiliation: Dipartimento di Fisica e Astronomia Galileo Galilei and CNISM, Università di Padova, Via Marzolo 8, Padova, 35131, Italy; Istituto Nazionale di Ottica (INO) Del Consiglio Nazionale Delle Ricerche (CNR), Sezione di Sesto Fiorentino, Via Nello Carrara, Sesto Fiorentino, 1-50019, Italy; Department of Interdisciplinary Studies, School of Electrical Engineering, Tel Aviv University, Tel Aviv, 69978, Israel

Abstract: We propose a possibility to simulate the exciton-polariton (EP) system in the lossless limit, which is not currently available in semiconductor microcavities, by means of a simple optical dual-core waveguide, with one core carrying the nonlinearity and operating close to the zero-group-velocity-dispersion point, and the other core being linear and dispersive. Both two-dimensional (2D) and one-dimensional (1D) EP systems may be emulated by means of this optical setting. In the framework of this system, we find that, while the uniform state corresponding to the lower branch of the nonlinear dispersion relation is stable against small perturbations, the upper branch is always subject to the modulational instability. The stability and instability are verified by direct simulations too. We analyze collective excitations on top of the stable lower-branch state, which include a Bogoliubov-like gapless mode and a gapped one. Analytical results are obtained for the corresponding sound velocity and energy gap. The effect of a uniform phase gradient (superflow) on the stability is considered too, with a conclusion that the lower-branch state becomes unstable above a critical wave number of the flux. Finally, we demonstrate that the stable 1D state may carry robust dark solitons.


Volume: 90 (4)      Pages from: 043202  to: 043202

More Information: The authors acknowledge partial support from Universita di Padova (Grant No. CPDA118083), Cariparo Foundation (Eccellenza Grant No. 11/12), and MIUR (PRIN Grant No. 2010LLKJBX). The visit of B.A.M. to Universita di Padova was supported by the Erasmus Mundus EDEN Grant No. 2012-2626/001-001-EMA2. L.S. thanks F. M. Marchetti for useful e-discussions.
DOI: 10.1103/PhysRevE.90.043202

Citations: 6
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