Joel Bellessa

Coherent emission from a disordered organic semiconductor induced by strong coupling with surface plasmons.

In this Letter, we show that the strong coupling between a disordered set of molecular emitters and surface plasmons leads to the formation of spatially coherent hybrid states extended on macroscopic distances. Young-type interferometric experiments performed on a system of J-aggregated dyes spread on a silver layer evidence the coherent emission from different molecular emitters separated by several microns. The coherence is absent in systems in the weak-coupling regime demonstrating the key role of the hybridization of the molecules with the plasmon.

Confined Tamm plasmon lasers.

We demonstrate that confined Tamm plasmon modes can be advantageously exploited for the realization of new kind of metal/semiconductor lasers. Laser emission is demonstrated for Tamm structures with various diameters of the metallic disks which provide the confinement. A reduction of the threshold with the size is observed. The competition between the acceleration of the spontaneous emission and the increase of the losses leads to an optimal size, which is in good agreement with calculations.

Emission of Tamm plasmon/exciton polaritons

We report on the observation of the strong coupling regime occurring between a Tamm plasmon (TP) mode and an exciton from inorganic quantum wells (QWs). The sample is formed by a silver thin film deposited onto an AlAs/GaAlAs Bragg reflector containing InGaAs QWs located in the high refractive index layers. Angular resolved reflectometry experiments evidence a clear anticrossing in the dispersion relations, a signature of the strong coupling regime. The Rabi splitting energy is 11.5 meV. The experimental data are in very good agreement with simple transfer matrix calculations. The emission from low and high energy TP/exciton polaritons is also demonstrated.

Particularities of surface plasmon?exciton strong coupling with large Rabi splitting

This paper presents some of the particularities of the strong coupling regime occurring between surface plasmon (SP) modes and excitons. Two different active materials were deposited on a silver film: a cyanine dye J-aggregate, and a two-dimensional layered perovskite-type semiconductor. The dispersion relations, which are deduced from angular resolved reflectometry spectra, present an anticrossing characteristic of the strong coupling regime. The wavevector is a good parameter to determine the Rabi splitting. Due to the large interaction energies (several hundreds of milli-electron-volts), the calculations at constant angle can induce an overestimation of the Rabi splitting of more than a factor of two. Another property of polaritons based on SP is their nonradiative character. In order to observe the polaritonic emission, it is thus necessary to use particular extraction setups, such as gratings or prisms. Otherwise only the incoherent emission can be detected, very similar to the bare exciton emission.

Single photon source using confined Tamm plasmon modes

We evaluate the potential of confined Tamm plasmon structures for single photon extraction. A single quantum dot is inserted in a structure consisting of a gold microdisk deposited on a distributed Bragg reflector. The quantum dot exciton line experiences acceleration of spontaneous emission while the biexciton line experiences inhibition. This property leads to non-linearities in the emission dynamics and the photon statistics as a function of the excitation rate. We show that the device operates as a single photon source with a measured brightness of 0.20 ± 0.02 collected photons per pulse. By modeling the extraction efficiency, we show that efficiencies around 60% can be reached in optimized structures.

Core-shell gold J-aggregate nanoparticles for highly efficient strong coupling applications

We have developed a straightforward synthetic route to prepare core-shell systems based on gold nanoparticles (NPs) surrounded with J-aggregates molecules. This synthesis allows the direct and efficient coating, at room temperature, of pretreated citrate-stabilized gold NPs with 5, 5′, 6, 6′-tetrachloro-1-1′-diethyl-3, 3′-di (4-sulfobutyl)-benzimidazolocarbocyanine (TDBC), without supplementary adding of salts and bases during the synthesis. As the size of gold particle is tunable, the precise optimization of the strong coupling between the electronic transitions of organic components (TDBC) and the plasmon modes of the gold NPs is achieved corresponding to a Rabi energy of 220 meV, a value not yet obtained in such a system.

Lasing in a hybrid GaAs/silver Tamm structure

We demonstrate that lasing can be obtained with the Tamm plasmon modes appearing at the interface between a multilayered dielectric structure and a metal. The sample consists in InGaAs/GaAs quantum wells embedded in an AlAs/AlGaAs Bragg reflector, on top of which a silver film was evaporated. A superlinear increase of the emission is observed under optical pumping as well as a drastic concentration of the emission pattern around the vertical direction, evidencing a lasing effect. Due to the particular features of these surface modes, Tamm lasers open interesting perspectives for the realization of integrated microlasers.

Enhanced light extraction from InGaN/GaN quantum wells with silver gratings

We demonstrate that an extraction enhancement by a factor of 2.8 can be obtained for a GaN quantum well structure using metallic nanostructures, compared to a flat semiconductor. The InGaN/GaN quantum well is inserted into a dielectric waveguide, naturally formed in the structure, and a silver grating is deposited on the surface and covered with a polymer film. The polymer layer greatly improves the extraction compared to a single metallic grating. The comparison of the experiments with simulations gives strong indications on the key role of weakly guided modes in the polymer layer diffracted by the grating.

Emission of hybrid organic-inorganic exciton/plasmon mixed states

In this letter the authors experimentally demonstrate the strong coupling regime at room temperature between a surface plasmon and an exciton from an auto-organized quantum well. The sample is formed by a two dimensional layered perovskite-type semiconductor: s(C6H5C2H4–NH3)PbI4, spin coated onto a silver film. The dispersion lines resulting from reflectometry experiments performed at room temperature in the Kretschmann geometry present an anticrossing with a Rabi splitting of 167meV. The emission of the low energy polariton is presented.

The Green’s Function Description of Emission Enhancement in Grated LED Structures

Using scattering to improve light extraction from semiconductors is a widely adopted method to increase the efficiency of modern light-emitting devices. Recently, there has also been much interest in the potential emission enhancement provided by the strong coupling between surface plasmons and semiconductor emitters. In this study, we develop a Greens function-based model to describe the emission enhancement and modification in optical properties obtained as a result of scattering and plasmon engineering. The Greens function method is used to answer fundamental questions regarding luminescence enhancement in periodically grated GaN light-emitting structures. The Greens function approach is a very attractive analytical method to studying the emission properties of grated multilayer structures, providing insight beyond numerical solutions. Modeling results from reflectometry measurements of silver-grated GaN structures allows to explain experimentally observed interference features. A discussion regarding the role of periodic grating in enhancing emission from the structures is included.