Optical spectrum and electromagnetic-field distribution at double-groove metallic surface gratings

Abstract

The Greens function model [8] for calculating the reflection and transmission of light at etched single-groove gratings on both sides of a thin silver film was extended to study the case of double-groove gratings. A splitting of surface-plasmon-polariton (SPP) modes was found due to electromagnetic (EM) coupling between the two grooves in the complex unit-cell of the grating. Spectral features corresponding to the split SPP branches as well as the minigap between them were found in this system. From the full spatial distributions of the total EM field, the high-surface-field regions, the coupling between two grooves in the same complex unit-cell and the coupling between two nearby grooves located at the upper and lower surfaces of the metal film can be identified.

Nanogroove array on thin metallic film as planar lens with tunable focusing

“…In the case of the extraordinary transmission of light through a metal film with a periodic nanoslit array, the surface polaritons supported by the slits play a minor role in the phenomenon, and what is more it is not necessary to have slits that completely pierce the metallic film to achieve the enhanced transmission 4 . When a periodic nanogroove array is illuminated by p−polarized light, whose magnetic vector is parallel to the generators of the array, surface plasmon polaritons (SPPs) associated with the film-cladding and the film-substrate interfaces are excited 4,5 , and are diffracted by the structure into transmitted volume waves in the substrate. The periodicity of the array enhances the excitation of surface plasmon polaritons associated with the cladding-film interface and the conversion of surface plasmon polaritons associated with the substrate-film interface into volume waves in a range of SPP frequencies whose wavenumbers are in the vicinity of the boundary of the second Brillouin zone, i.e.…”

Asymmetrically filled slits in a metal film that split a light beam into two depending on its wavelength

“…If η L = η R = 0 for a PEC, we can explicitly express 22 the continuous Fourier expansion coefficients A s (β), A a (β), B s (β) and B a (β) by the discrete Fourier expansion coefficients a j sn , b j sn , a j an and b j an through Eqs. (13), (14), (15) and (16). If there exists only one slit (j = 0 and z 0 = 0), the PEC single slit does not couple symmetric modes to anti-symmetric ones 25 .…”

Surface plasmon enhanced differential reflectance technique for ultra-thin film monitoring

“…It could lead to strong field enhancement in nanoscale and this makes the spectrum extremely sensitive to the physical properties of the environment [7]. Previous studies showed that SPPs could lead to the enhanced reflection and DR near the resonance frequency [14][15][16]. Taking advantage of SPPs offers a potential approach to significantly enhance the sensitivity of the DR technique and extend the applications of this technique.…”