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Devices Physics > Nanophotonics and plasmonic devices
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Surface plasmons polaritons (SPP) are surface waves bound to metal/dielectric interfaces that arise from the interaction between light and mobile surface charges. With the recent advances in nanofabrication, there has been a renewed interest in exploiting the optical properties of metals structured at the nanoscale. They have allowed new classes of materials to emerge. Plasmonic structures enable light propagation and light confinement beyond the diffraction limit, and metamaterials provide a route to designing artificial materials with any (positive, negative, anisotropic...) refractive index. They offer new possibilities for manipulating light, and can be integrated in new devices for photovoltaics, optoelectronics, and infrared instrumentation tools. Our aim is to investigate the fundamental properties of metal and metal-semiconductor nanostructures, and to design, fabricate and demonstrate new devices for efficient light absorption, propagation, and emission in the (near-, mid-, and far-) infrared wavelength range.

1D and 2D plasmonic crystals, nanostructured plasmonic waveguides

Metallic films perforated by an array of 1D or 2D periodical subwavelength apertures play the role of plasmonic crystals. The apertures allow coupling mechanisms between surface plasmon waves. The dispersion curves of 1D and 2D plasmonic crystals have been characterized by high-resolution optical transmission measurements, and compared to numerical results. These studies have revealed new properties of anisotropic 2D plasmonic crystals and nanostructured (1D) thin plasmonic waveguides.

PHYDIS 2D anisotropic plasmonic crystals

A coupling between modes propagating in two nearly orthogonal directions (forming an angle of 77° in this sample) is evidenced for a rectangular array of holes perforated in a gold film. The coupling results in a narrow band gap for nonzero wavevectors and in a coupled mode with a large density of states and a strong radiative damping. We show that the gap location in the (ω,k) space can be precisely tuned by changing the 2D periods.

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PHYDISPHYDIS Thin nanostructured plasmonic waveguides: tailoring the radiative and non-radiative properties

We show that the radiative emission can be enhanced or inhibited in nanostructured thin-film plasmonic waveguides by a slight modification of the refractive index of the substrate (δn/n~1%), allowing to control the propagation regime of surface plasmon waves along the air/metal interface (a low-loss propagation regime, and a radiative propagation regime).

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PHYDIS Surface modes on nanostructured metallic surfaces (collab. Christophe Sauvan and Philippe Lalanne (LCFIO))

An analytical model that provides closed-form expressions for the dispersion relation of surface modes supported by metal/dielectric interfaces perforated by 2D arrays of subwavelength apertures has been derived.

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Squeezing light absorption in nanoscale metal-semiconductor-metal structures

PHYDIS Efficient light confinement and absorption in MSM nanostructures (photodetectors, photovoltaics,...)

We have proposed new concepts for efficient light absorption in nanoscale metal-semiconductor-metal structures. They have been analyzed both theoretically and experimentally, leading to the first theoretical and experimental demonstration of efficient absorption (10-15%) in nanoscopic (40nm x 100nm) GaAs wires.

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Versatile and efficient optical filters for multispectral IR imagery

PHYDIS Band-pass filters for the mid-infrared wavelength range (collab. R. Haïdar (ONERA/DOTA))

We have achieved the fabrication of large-area metallic and dielectric drilled membranes. Free-standing metallic gratings have been designed and fabricated for mid-infrared filtering. They show quasi-total resonant transmission (>90%), and can act as efficient optical band-pass filters with tunable bandwidth.

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Among the other projects (collaborations)...

Highly directional light sources via SPP excitation

Broadband diffractive optics

Coupled 1D gold cavities

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Collab. François Marquier, Marine Laroche and Jean-Jacques Greffet (LFCIO)

Collab. Philippe Lalanne (LCFIO), Mane-Si-Laure Lee and Brigitte Loiseaux (TRT)

Collab. Aude Barbara and Pascal Quémerais (Institut Néel)

Development of new tools

Our work is based on the development of new tools for sample fabrication, experiments and modelling.

Original fabrication processes
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  • Double lift-off technique for high aspect ratio metallic nanostructures.
  • Nanostructured membranes for wide-area dielectric and metallic free-standing gratings.

Versatile optical setup
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Reflection and transmission measurements (0.5-16μm, 0°-270°) with angular and spectral resolutions as low as 0.3° and 0.5 cm-1, respectively.

Computational methods

We are developing new tools around really rigorous Maxwell electromagnetic equations formulation (topological expressions in terms of E, B, D, H) delaying the numerical approximations when we write the physical linear constitutive equations between (E, B) and (D, H).


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