Spatially uniform enhancement of single quantum dot emission using plasmonic grating decoupler

International audience1 We demonstrate a spatially uniform enhancement of individual quantum dot (QD) fluorescence emission using plasmonic grating decouplers on thin gold or silver films. Individual QDs are deposited within the grating in a controlled way to investigate the position dependency on both the radiation pattern and emission enhancement. We also describe the optimization of the grating decoupler. We achieve a fluorescence enhancement ~3 times higher than using flat plasmon film, for any QD position in the grating. Future optical quantum devices require the development of photonic sources with control of light down to the single photon limit. Excellent examples of single photon emitters are the colloidal nanocrystal quantum dots (QDs) which are considered as the building blocks for future quantum devices such as quantum qubits and quantum cryptographic devices 1,2. The application area of quantum emitters is wide and these applications require control of their emission such as emission rate, polarization, spectral properties, collection efficiency etc. Integration of single molecule or nanocrystals into plasmonic structures has recently proved to be one of the most promising yet challenging ways to control the emission properties at the single photon level 3,

Room temperature single-photon sources based on single colloidal nanocrystals in microcavities

Abstract Direct lithography of resist blends, embedding semiconductor colloidal nanocrystals (NCs) is an innovative way to achieve nanopositioning of NCs in quantum-confined optical resonators. In this work, we show a new appealing approach for the fabrication of single-photon sources operating at room temperature by localizing semiconductor colloidal NCs into vertical planar microcavities with lithographic techniques

From scattering regime to strong localization: a statistical analysis of the near-field intensity on random gold films

International audienceRandom metallic films have very specific optical properties due to disorder. Strong localization of electromagnetic fields can be observed due to plasmons. This localization strongly depends on excitation conditions, and different optical regimes can exist. To characterize these regimes, we investigated the spatial intensity correlation functions using near-field scanning optical microscopy for different excitation wavelengths and different incident polarization states. The transition between a weak scattering regime where no plasmon resonances are excited and a regime where strong plasmon resonances occur has clearly been observed. In the strong plasmonic regime, by varying the incident polarization direction, the shape of the correlation function has been correlated to the intensity enhancement which raises the possibility to control the intensity localization using the incident polarization state

3D vector distribution of the electro-magnetic fields on a random gold film

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Photostability and long-term preservation of a colloidal semiconductor-based single photon emitter in polymeric photonic structures

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Suppression of grey state and optimization of the single photon emission of a colloidal semiconductor at room temperature

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Influence of the cluster's size of random gold nanostructures on the fluorescence of single CdSe–CdS nanocrystals

International audienceIt is well known that coupling a single emitter to metallic structures modifies drastically its fluorescence properties compared to single emitter in vacuum. Depending on various parameters such as the nature of the metal or the geometry of the metallic structure, quenching or intensity enhancement as well as radiative processes acceleration are obtained through the creation of new desexcitation channels. The use of metallic random structures gives the opportunity to magnify the effect of the coupling by strongly confined electromagnetic fields. A gold film at the perco-lation threshold is an interesting illustration of that effect. Here, we study the influence of the method used to realize these films through two different examples. First, we show that the mean size of the gold clusters constituting the film depends on the deposition method. Even if similar optical properties (in particular far-field absorption) are exhibited by the structures, crucial differences appear in the fluores-cence of single emitters when coupled to the two kinds of D. Canneson · S. Buil · X. Quélin () · J.-P. Hermier Groupe d' random gold film. Especially, we focus our attention on the creation of desexcitation channels and show that they are cluster size dependent

FDTD simulations of localization and enhancements on fractal plasmonics nanostructures

International audienceA parallelized 3D FDTD (Finite-Difference Time-Domain) solver has been used to study the near-field electromagnetic intensity upon plasmonics nanostructures. The studied structures are obtained from AFM (Atomic Force Microscopy) topography measured on real disordered gold layers deposited by thermal evaporation under ultra-high vacuum. The simulation results obtained with these 3D metallic nanostructures are in good agreement with previous experimental results: the localization of the electromagnetic intensity in subwavelength areas (" hot spots ") is demonstrated; the spectral and polarization dependences of the position of these " hot spots " are also satisfactory; the enhancement factors obtained are realistic compared to the experimental ones. These results could be useful to further our understanding of the electromagnetic behavior of random metal layers

High Directional Radiation of Single Photon Emission in a Dielectric Antenna

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Blinking suppression and biexcitonic emission in thick-shell CdSe/CdS nanocrystals at cryogenic temperature

International audienceThe fluorescence of single colloidal thick-shell CdSe/CdS nanocrystals (NCs), at cryogenic temperature (4 K) and room temperature (RT), is studied using the intensity autocorrelation function (ACF) and lifetime measurements. The radiative and Auger decay rates corresponding to the desexcitation of the charged biexcitonic state are determined through an original method of photon postselection. Especially, the charged biexciton quantum yield increases from about 15% at RT to 60% at 4 K. The high inhibition of Auger recombination already observed for the trion state of CdSe/CdS NCs at low temperature is also demonstrated for the charged biexcitonic state. At 4 K, the ACF is equal to 1 for time scales ranging from 50 ns to 200 ms. In contrast with RT operation, the intensity of the trion emission is then perfectly stable and no blinking is observed. All the results highlight the strong confinement of the charge carriers in the CdSe core