Radiative coupling of quantum dots in photonic crystal structures

Momchil Minkov and Vincenzo Savona
Phys. Rev. B 87, 125306 – Published 11 March 2013

Abstract

We derive a general formalism to model the polariton states resulting from the radiation-matter interaction between an arbitrary number of excitonic transitions in semiconductor quantum dots and photon modes in a photonic crystal structure in which the quantum dots are embedded. The Maxwell equations, including the linear nonlocal susceptibility of the exciton transitions in the quantum dots, are cast into an eigenvalue problem, which can be applied to any structure whose photon modes can be computed with reliable accuracy, and in addition naturally allows for disorder effects to be taken into account. We compute realistic photon modes using Bloch-mode expansion. As example systems, we study typical InGaAs quantum dots in a GaAs photonic crystal structures—an Ln cavity or a W1 waveguide. For a single dot, we reproduce known analytical results, while for the two-dot case we study the radiative excitation transfer mechanism and characterize its strength, the dependence on the detuning between quantum dot and photon modes, and the dependence on interdot distance. We find in particular that the interdot radiative coupling strength can reach 100μeV in a short cavity, and its decay with distance in longer cavities and waveguides is determined by the group velocity of the exchanged photons and their radiative lifetime. We also show that, for an Ln cavity of increasing length, the radiative excitation transfer mechanism is subject to a crossover from a regime where a single photon mode is dominating, to a multimode regime—occurring around n = 150 for the system under study.

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  • Received 20 December 2012

DOI:https://doi.org/10.1103/PhysRevB.87.125306

©2013 American Physical Society

Authors & Affiliations

Momchil Minkov and Vincenzo Savona

  • Institute of Theoretical Physics, Ecole Polytechnique Fédérale de Lausanne EPFL, CH-1015 Lausanne, Switzerland

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Vol. 87, Iss. 12 — 15 March 2013

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