Optical transmission through double-layer metallic subwavelength slit arrays

Abstract

We present measurements of transmission of infrared radiation through double-layer metallic grating structures. Each metal layer contains an array of subwavelength slits and supports transmission resonance in the absence of the other layer. The two metal layers are fabricated in close proximity to allow coupling of the evanescent field on individual layers. The transmission of the double layer is found to be surprisingly large at particular wavelengths, even when no direct line of sight exists through the structure as a result of the lateral shifts between the two layers. We perform numerical simulations using rigorous coupled wave analysis to explain the strong dependence of the peak transmission on the lateral shift between the metal layers.

Transmission and reflection properties of two-dimensional finite metal crystals

“…Fields are similar to those obtained for the structure without a horizontal shift between the layers despite the fact, that upper metal stripes screen the air gaps in lower grating layers. This feature is in agreement with results presented in [25], where a bilayer structure with introduced spatial shift of a half of grating period showed high resonant transmission despite the lack of direct line of sight. However, the analysed structure shows significantly broader transmission band.…”

Electromagnetic Response and Broadband Utilities of Planar Metamaterials

“…The passband gets more and more broadened with sharper edges when the system contains more metallic layers. In contrast, these results can not be observed when the wave propagation is dictated by evanescent coupling of SPP modes (Miyamaru & Hangyo 2005;Ye & Zhang 2005;Chan, Marcet et al 2006;Tang, Peng et al 2007;Ortuno, Garcia-Meca www.intechopen.com et al 2009;Marcet, Hang et al 2010;Zhou, Huang et al 2010). Measured transmission spectra are in good agreement with calculations for the model systems with different metallic layers.…”

“…The frequency of such an EOT transmission peak is not only scaled to the period of hole arrays, but also very sensitive to the incident angle as the resonant tunneling occurs via the in-plane Bragg-scattering channels. Very recently, similar phenomena of the EOT through cascaded metallic multi-layers, which are perforated with one-dimensional gratings or two-dimensional hole arrays, have also been brought into attention (Miyamaru & Hangyo 2005;Ye & Zhang 2005;Chan, Marcet et al 2006;Tang, Peng et al 2007;Ortuno, Garcia-Meca et al 2009;Marcet, Hang et al 2010;Zhou, Huang et al 2010). The resonant coupling among the SPP modes on different layers can be tuned by the spacing distance and lateral displacement of hole arrays at different layers, leading to tunable transmission peaks and zeros in spectra.…”

Multiple intersection properties of optical resonance modes in metallic metamaterials

“…8 The introduction of air gaps and/or lateral displacements between the perforated metallic plates in stacked systems has led to more complex and interesting optical properties. [9][10][11][12][13][14][15][16][17][18] We have been investigating the physical mechanism for the behavior of the Fabry-Perot-like waveguide resonance modes in order to understand clearly the optical transmission properties of stacked metallic slit-array systems. [19][20][21] To date, we have formulated the effective refractive index of the air-gap layer that is sandwiched by the slit-array slabs, 19 and demonstrated that most of the intersections of the optical resonance modes can be regarded fundamentally as anticrossings, in which the mode repulsions are recognized only when the effective refractive indices in the air-gap regions are considerably increased.…”