Surface plasmon generation through hybridization with Tamm modes

Abstract

Tamm plasmons (TPs) are electromagnetic modes formed at the interface between a photonic structure and a metallic layer [1]. They present optical properties at the boundary between microcavity modes and surface plasmons (SP). Compared to conventional SPs, Tamm plasmons present the advantage to be radiative and also to have reduced losses due to the larger penetration of the electric field in the dielectric part of the structure. The coupling between TP and semiconductor nanostructures (quantum dots, quantum wells) have led to the experimental demonstration of bright single photon sources [2], TP-exciton polaritons [3], and polarized laser emission [4]. Another very promising feature of TP modes is that they coexist outside the light-cone with the conventional SP present at the metal/air interface [5]. Here, we will report on the experimental observation of the electromagnetic coupling between TP and SP modes in a novel metal/semiconductor integrated structure comprising a buried quantum dot-based light source and a metallic surface grating for light extraction (Fig. 1). The TP mode is excited by the photoluminescence emission of quantum dots grown in the top part of the dielectric mirror. This allows for indirect excitation of the SP at the silver/air interface, provided that a non-negligible spatial overlap between the two modes takes place in the thin metallic layer. The hybrid nature of such a TP/SP mode propagating in the planar silver thin film is demonstrated by the observation of a spatial beating along the propagation. This beating turns out to be in very good agreement with the results of numerical calculations, based on the wave-vector mismatch existing between the two modes. Our results pave the way to a new generation of hybrid metal/semiconductor integrated optical devices for both energy-sensitive surface detection and excitation of surface plasmons via Tamm plasmons.