Year: 2014
Type: article
Abstract: Sinusoidally patterned metallic surfaces, known as plasmonic gratings, constitute one of the principal structures which allow to achieve the coupling between an incident light beam and a Surface Plasmon Polariton mode. A variety of phenomena are available when the grating is rotated of an azimuthal angle with respect to the incidence plane. Aim of this work is a comprehensive investigation of the propagation properties of the surface mode under this configuration, correlating the role of the anisotropy introduced by the grating to the position and shape of the plasmonic resonance dip in the reflectance spectra. Analytical models and physical interpretations are provided; both experimental and computational means are exploited in order to validate the models, including the observation of innovative effects. Thin-film coupled modes, the Long Range and Short Range Surface Plasmon Polaritons, are studied and experimentally observed in the azimuthally rotated configuration. Special attention is paid to the role of the plasmon radiative losses, due to the scattering by the grating. Their dependence on the grating amplitude and the plasmon propagation direction is unraveled, and correlated to the width of the observed plasmonic resonances. The outcomes of these analyses lead to the evaluation of the sensitivity and Figure of Merit achievable when the considered configurations are exploited in the framework of Surface Plasmon Resonance sensing. The developed concepts and methods are proved to be valuable tools to predict and understand the response of actual plasmonic structures applied as sensing devices against gaseous analytes. Experimental tests of the plasmonic platforms as TNT, hydrogen and aromatic compounds sensors are reported, giving promising results. A particularly remarkable experiment is the combined exploitation of Long Range modes and azimuthally rotated configuration to sensibly enhance the performance of a xylene sensor
Author: Enrico Gazzola
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W158671362