Role of Wood anomalies in optical properties of thin metallic films with a bidimensional array of subwavelength holes

Abstract

Recents works deal with the optical transmission on arrays of subwavelength holes in a metallic layer deposited on a dielectric substrate. Making the system as realistic as possible, we perform simulations to enlighten the experimental data. This paper proposes an investigation of the optical properties related to the transmission of such devices. Numerical simulations give theoretical results in good agreement with experiment and we observe that the transmission and reflection behaviour correspond to Fano's profile correlated with resonant response of the eigen modes coupled with nonhomogeneous diffraction orders. We thus conclude that the transmission properties observed could conceivably be explained as resulting from resonant Wood's anomalies.

Transition from localized surface plasmon resonance to extended surface plasmon-polariton as metallic nanoparticles merge to form a periodic hole array

“…This is useful since when light is coupled to SPPs the enhanced fields associated with such modes lead to an increase in the absorptionabsorption is thus another indicator of the presence of SPP modes. 19,[23][24][25] The first-order scattered silica light lines are plotted as dotted lines in Fig. 7.…”

Resonant backward scattering of light by a subwavelength metallic slit with two open sides

“…The role of resonant Wood's anomalies and Fano's profiles in the resonant transmission were explained in the study. 8 The phenomena involved in propagation through hole arrays are different from those connected with slit arrays. In a slit waveguide there is always a propagating mode inside the channel, while in a hole waveguide all modes are evanescent for hole diameters smaller than approximately a wavelength.…”

“…1,2, 3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39 ). In the last few years, a great number of studies have been devoted to the nanostructures in metal films, namely a single aperture, a grating of apertures and an aperture surrounded by grooves.…”

Bounded modes to the rescue of optical transmission

“…s r + s h . So, the Fano profiles of the transmission (but also of the reflection) result from a superposition of resonant and nonresonant contributions to the observed diffraction order [10][11]. As a result, in Fig.5 one can observe the calculated transmission (black curve) in comparison with the non-homogeneous resonant order amplitude (red curve).…”

“…As a consequence, despite alternative theoretical interpretations, a large experimental consensus, many theoretical results, tend to prove that the SPs interpretation was correct in the metallic films cases, and must be extended to a bounded mode interpretation in the most general cases [10][11][12]. It is only the transposition of the 1960's results about one-dimensional reflection gratings to bidimensional transmission gratings.…”