Heat flux splitter for near-field thermal radiation

We demonstrate the possibility to efficiently split the near-field heat flux exchanged between graphene nano-disks by tuning their doping. This result paves the way for the developement of an active control of propagation directions for heat fluxes exchanged in near-field throughout integrated nanostructures networks

Plasmonic-photonic crystal coupled nanolaser

We propose and demonstrate a hybrid photonic-plasmonic nanolaser that combines the light harvesting features of a dielectric photonic crystal cavity with the extraordinary confining properties of an optical nano-antenna. In that purpose, we developed a novel fabrication method based on multi-step electron-beam lithography. We show that it enables the robust and reproducible production of hybrid structures, using fully top down approach to accurately position the antenna. Coherent coupling of the photonic and plasmonic modes is highlighted and opens up a broad range of new hybrid nanophotonic devices

Optimal overlayer inspired by Photuris firefly improves light-extraction efficiency of existing light-emitting diodes

In this paper the design, fabrication and characterization of a bioinspired overlayer deposited on a GaN LED is described. The purpose of this overlayer is to improve light extraction into air from the diode's high refractive-index active material. The layer design is inspired by the microstructure found in the firefly Photuris sp. The actual dimensions and material composition have been optimized to take into account the high refractive index of the GaN diode stack. This two-dimensional pattern contrasts other designs by its unusual profile, its larger dimensions and the fact that it can be tailored to an existing diode design rather than requiring a complete redesign of the diode geometry. The gain of light extraction reaches values up to 55% with respect to the reference unprocessed LED.Comment: 9 pages, 9 Figures, published in Optics Expres

Engineering high aspect-ratio silicon nanostructures

Large-area high density vertical silicon nanowire arrays are fabricated by metal-assisted chemical etching. Two-dimensional silica colloidal crystal template or laser interference lithography are used to create gold metal nanohole arrays on a silicon substrate, which enables to precisely control the final diameter of the nanowires. The formation of ordered silicon nanowire arrays is due to selective and highly anisotropic etching of silicon induced by the gold patterned mask

Tuning the electromagnetic local density of states in graphene-covered systems via strong coupling with graphene plasmons

It is known that the near-field spectrum of the local density of states of the electromagnetic field above a SiC/air interface displays an intense narrow peak due to the presence of a surface polariton. It has been recently shown that this surface wave can be strongly coupled with the sheet plasmon of graphene in graphene-SiC heterosystems. Here, we explore the interplay between these two phenomena and demonstrate that the spectrum of the electromagnetic local density of states in these systems presents two peaks whose position depends dramatically both on the distance to the interface and on the chemical potential of graphene. This paves the way towards the active control of the local density of states.Comment: 6 pages, 4 figure

New concepts of integrated photonic biosensors based on porous silicon

International audienceno abstrac

Chemical composition of nanoporous layer formed by electrochemical etching of p-type GaAs

Abstract : We have performed a detailed characterization study of electrochemically etched p-type GaAs in a hydrofluoric acid-based electrolyte. The samples were investigated and characterized through cathodoluminescence (CL), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). It was found that after electrochemical etching, the porous layer showed a major decrease in the CL intensity and a change in chemical composition and in the crystalline phase. Contrary to previous reports on p-GaAs porosification, which stated that the formed layer is composed of porous GaAs, we report evidence that the porous layer is in fact mainly constituted of porous As2O3. Finally, a qualitative model is proposed to explain the porous As2O3 layer formation on p-GaAs substrate