We report here on the optical response of elliptical gold particles arranged in a rectangular lattice on glass and probed at non-normal incidence in reflection using spectroscopic Mueller matrix ellipsometry in the energy range 0.73 − 5.9 eV. The surface plasmon resonances, reshaped near the Rayleigh anomalies, are mapped out by full azimuthal rotation of the sample. The experimental Mueller matrices are discussed and interpretation is supported by finite element modelling of the Mueller-Jones matrix elements, which allows for identification of the dipolar and multipolar responses observed in the experimental spectra. The data show a strong polarization conversion around the surface plasmon resonances as a function of the azimuthal angle of incidence, also reshaped near the Rayleigh lines. An effective strong circular diattenuation is observed from the recorded Mueller matrix. We further argue the importance of Mueller matrix ellipsometry for metrology in the manufacture of metasurfaces, for understanding the effect of the lattice in metasurface design, and finally in validating computational methods.

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In this paper, absorption phenomena in a hollow waveguide with an inserted graded dielectric layer are studied, for the case of transverse electric (TE) wave propagation. The waveguide model aims to be applicable to a study of a potential cancer treatment by heating of gold nanoparticles (GNPs) inside the cancer cells. In our previous work, general exact analytical fomulas for transmission, reflection, and absorption coefficients were derived. These fomulas are further developed here to be readily applicable to the calculation of the absorption coefficient within the inserted lossy layer only, quantifying the absorption in the GNP-fed cancer tissue. To this end, we define new exact analytic scale factors that eliminate unessential absorption in the surrounding lossy medium. In addition, a numerical model was developed using finite element method software. We compare the numerical results for power transmission, reflection and absorption coefficients to the corresponding results obtained from the new modified exact analytic fomulas. The study includes both a simple example of constant complex permittivities, and a more realistic example where a dispersive model of permittivity is used to describe human tissue and the electrophoretic motion of charged GNPs. The results of the numerical study with both non-dispersive and dispersive permittivities indicate an excellent agreement with the corresponding analytical results. Thus, the model provides a valuable analytical and numerical tool for future research on absorption phenomena in GNP-fed cancer tissue.

In this paper, we study TEM-wave propagation inside a hollow coaxial waveguide filled with an inhomogeneous metamaterial composite, with a graded transition between a right-handed material (RHM) and an impedance-matched left-handed material (LHM). The graded transition and the TEM-wave propagation occur in the direction perpendicular to the boundary between the two media, which has been chosen to be the z-direction. The relative permittivity ɛ(ω, z) and permeability µ(ω, z) of the RHM-LHM composite vary according to hyperbolic tangent functions along the z-direction. The exact analytical solutions to Maxwell’s equations are derived, and the solutions for the field components and wave behavior confirm the expected properties of impedance-matched RHM-LHM structures. Furthermore, a numerical study of the wave propagation over an impedance-matched graded RHM-LHM interface, using the COMSOL Multiphysics software, is performed. An excellent agreement between the analytical results and numerical simulations is obtained, with a relative error of less than 0.1%. The present method has the ability to model smooth realistic material transitions, and includes the abrupt transition as a limiting case. Finally, the RHM-LHM interface width is included as a parameter in the analytical and numerical solutions, allowing for an additional degree of freedom in the design of practical devices using RHM-LHM composites.

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