Alexandre Baron

Scaling of the nonlinear response of the surface plasmon polariton at a metal/dielectric interface

Plasmonic systems involve interfaces containing metal and dielectric materials. In an effort to investigate the scaling of the nonlinear response of the surface plasmon polariton at a metal/dielectric interface, where the metal and dielectric present optical nonlinearity, we introduce a figure-of-merit that quantifies the contribution of the metal and the dielectric to the nonlinear response in this specific situation. In the case of self-action of the surface plasmon polariton for the gold/dielectric interface, we predict that the dielectric nonlinear response is dominant for strongly nonlinear dielectrics such as polydiacetylenes, chalcogenide glasses, or even semiconductors. The gold nonlinear response is dominant only in cases involving weakly nonlinear dielectrics such as silicon dioxide or aluminum oxide. We verify the relevance of the metric by investigating the process of optical switching via the third-order nonlinear response and discuss which gold/dielectric combinations have better switching behaviors.

Optical bistability with film-coupled metasurfaces

Metasurfaces comprising arrays of film-coupled, nanopatch antennas are a promising platform for low-energy, all-optical switches. The large field enhancements that can be achieved in the dielectric spacer region between the nanopatch and the metallic substrate can substantially enhance optical nonlinear processes. Here we consider a dielectric material that exhibits an optical Kerr effect as the spacer layer and numerically calculate the optical bistability of a metasurface using the finite element method (FEM). We expect the proposed method to be highly accurate compared with other numerical approaches, such as those based on graphical post-processing techniques, because it self-consistently solves for both the spatial field distribution and the intensity-dependent refractive index distribution of the spacer layer. This method offers an alternative approach to finite-difference time-domain (FDTD) modeling. We use this numerical tool to design a metasurface optical switch and our optimized design exhibits exceptionally low switching intensity of 33u2009u2009kW/cm2, corresponding to switching energy on the order of tens of attojoules per resonator, a value much smaller than those found for most devices reported in the literature. We propose our method as a tool for designing all-optical switches and modulators.

Isotropic Huygens dipoles and multipoles with colloidal particles

Huygens sources are elements that scatter light in the forward direction as used in the Huygens-Fresnel principle. They have remained fictitious until recently when experimental systems have been fabricated. In this Rapid Communication, we propose isotropic meta-atoms that act as Huygens sources. Using clusters of plasmonic or dielectric colloidal particles, Huygens dipoles that resonate at visible frequencies can be achieved with scattering cross sections as high as five times the geometric cross section of the particle surpassing anything achievable with a hypothetical simple spherical particle. Examples are given that predict extremely broadband scattering in the forward direction over a 1000 nm wavelength range at optical frequencies. These systems are important to the fields of nanoantennas, metamaterials, and wave physics in general as well as any application nthat requires local control over the radiation properties of a system as in solar cells or biosensing.

Localization of light at vanishingly small disorder-levels with heavy photons

We show that the key parameter driving the spatial extent of localized modes formed in randomly-perturbed periodic media near the band edge is the effective photon mass rather than the group index.

Analytic modeling of metmaterial absorbers

We present a fully analytical model that describes ideal absorbing metasurfaces composed of film-coupled optical nanoantennas. The model predicts the spectrum and the angular dependence of the absorption and is compared to full-wave numerical simulations.

Large and ultrafast nonlinear absorption of an air/gold plasmonic waveguide

We investigate theoretically and experimentally the nonlinear propagation of surface plasmons on an air/gold interface which reveals large and ultrafast (~100 fs) self-induced absorption. The experiment enables a direct measurement of the third-order nonlinear susceptibility.

Scaling of the nonlinear response of metal/dielectric plasmonic waveguides

The scaling of the nonlinear response of a single-interface plasmonic waveguide is studied, where both the metal and dielectric display nonlinearity. We introduce a figure-of-merit that guides metal/dielectric nanophotonic device design for specific applications.