Spontaneous emission of guided polaritons by quantum dot coupled to metallic nanowire: Beyond the dipole approximation

Abstract

In this paper, we theoretically analyze the emission of guided polaritons accompanying spontaneous recombination in a semiconductor quantum dot coupled to metallic nanowire. This study is aimed to shed light on the interaction between optically excited quantum emitters and metallic nanowaveguides beyond the validity of dipole approximation. To the best of our knowledge, this is the first time the geometry of quantum emitter and spatial inhomogeneity of the electric field constituting the fundamental polariton mode are fully taken into account. Even though we performed the analysis for disk-like quantum dot, all the conclusions are quite general and remain valid for any emitter with nanometer dimensions. Particularly, we found that the strong inhomogeneity of the electric field near the nanowire surface results in a variety of dipole-forbidden transitions in the quantum dot energy s ctra. It was also unambiguously shown that there is a certain nanowire radius that gives maximum emission efficiency into the fundamental polariton mode. Since the dipole approximation breaks for nanowires with small radii and relatively big nanoemitters, the above features need to be considered in the engineering of plasmonic devices for nanophotonic networks.

Probing Electric and Magnetic Vacuum Fluctuations with Quantum Dots

“…The mode is strongly confined to the nanowire surface and has a larger energy density per photon than a metal interface, which is why field gradients are further enhanced leading to a larger effect of the mesoscopic moment. The contribution of Γ (2) is again negligible since G (2) = 0.14. The coupling to radiation and ohmic-lossy modes is modelled as a point-dipole in the simple quasi-static approximation 27,28 , which gives excellent agreement with the full electrodynamic computation.…”

“…Note that the dipole approximation is more robust for atoms and other high-symmetry emitters, since the first nonvanishing contribution is Γ (2) , which has a weight of (kLQD) 2 with respect to Γ (0) . In the following we discuss the first-order contribution, Γ (1) , in quantitative terms.…”

Quantum electrodynamics of resonance energy transfer in nanowire systems

“…These have been the focus of extensive research during the last few decades [17][18][19][20]. Their length is sufficiently large for easy manipulation as building blocks in fabricating superstructures.…”

Photoluminescence of a quantum-dot molecule

“…F€ orster's theory was extended a few years later by Dexter 13 to include transfer by means of dipole-forbidden transitions, which occur due to the overlapping of the dipole field of a sensitizer with the quadrupole field of an activator and exchange effects. The past decade has witnessed the emergence of many experimental [14][15][16][17] and theoretical [18][19][20][21][22][23][24][25] works devoted to the investigation of various aspects of nonradiative energy exchange between semiconductor quantum dots (QDs), including the studies on how the exchange is affected by the nearby metallic nanoparticles 26,27 and photon modes of optical microcavities. 28,29 The widespread interest in different kinds of QD nanostructures-including molecules and oligomers, 30,31 two-and three-dimensional supercrystals, [32][33][34][35] as well as dendrites 36,37 -is explained by the sizedependent energy spectrum of QDs, their high chemical stability, and fluorescence brightness (the product of the quantum yield and extinction coefficient).…”