X-ray Computed Tomography for Characterization of Expanded Polystyrene (EPS) Foam.

Expanded polystyrene (EPS) foam is widely used in building and construction applications for thermal and acoustic insulation. This material is nearly transparent for X-rays, making it difficult to characterize its pore structure in 3D with X-ray tomography. Because of this difficulty, the pore network is often not investigated and is, thus, poorly known.

Surface plasmon mode steering and negative refraction.

The propagation of surface plasmon beams through singly and doubly periodic metallic gratings is analyzed both in real and Fourier spaces. Large beam steering effects are experimentally revealed by probing the isofrequency surfaces (IFS) related to propagating plasmonic Bloch waves inside the gratings. In particular, negative refraction is demonstrated close to the Bragg condition.

Refractive micro-optical elements for surface plasmons: from classical to gradient index optics.

Controlling the propagation of surface plasmons along a metal-dielectric interface is a key feature for the development of surface plasmon based circuits. We have designed various two-dimensional refractive dielectric optical elements for surface plasmons (SP) and characterized their capacity to route SP, using near- or far-field techniques. We first present basic devices analogous to usual optical components and the associated challenges for SP optics.

Optical chirality without optical activity: How surface plasmons give a twist to light.

Light interacts differently with left and right handed three dimensional chiral objects, like helices, and this leads to the phenomenon known as optical activity. Here, by applying a polarization tomography, we show experimentally, for the first time in the visible domain, that chirality has a different optical manifestation for twisted planar nanostructured metallic objects acting as isolated chiral metaobjects. Our analysis demon-strate how surface plasmons, which are lossy bidimensional electromagnetic waves propagating on top of the structure, can delocalize light information in the just precise way for giving rise to this subtle effect.

Wavelength selective nanophotonic components utilizing channel plasmon polaritons.

We fabricate and investigate wavelength selective components utilizing channel plasmon polaritons (CPPs) and operate at telecom wavelengths: a waveguide-ring resonator-based add-drop multiplexer (WRR-ADM) and a compact (3.75-microm-long) Bragg grating filter (BGF). The CPP waveguides represent 0.

Channel plasmon subwavelength waveguide components including interferometers and ring resonators.

Photonic components are superior to electronic ones in terms of operational bandwidth, but the diffraction limit of light poses a significant challenge to the miniaturization and high-density integration of optical circuits. The main approach to circumvent this problem is to exploit the hybrid nature of surface plasmon polaritons (SPPs), which are light waves coupled to free electron oscillations in a metal that can be laterally confined below the diffraction limit using subwavelength metal structures. However, the simultaneous realization of strong confinement and a propagation loss sufficiently low for practical applications has long been out of reach.