Unidirectional SPP excitation at asymmetrical two-layered metal gratings

Abstract

Abstract.A new configuration of a reflective one-dimensional surface-relief metallicgrating structure for unidirectional excitation of surface plasmon polaritons (SPPs) is proposed and numerically explored for plane wave normal incidence. The structure is embedded between two different dielectric media and composed of two layers, each of them consisted of periodically placed rectangular metal stripes. It is shown that even a small horizontal shift between these two layers, or a change of dielectric contrast of the grating fillings, may redirect energy flow propagation in a vicinity of the grating structure. From these two cases of counter propagating energy flows only one shows the field behaviour typical for SPP excitation. This evident directivity phenomenon exists together with high concentration of the electromagnetic field at the periodic structure. The configurations analysed may be useful in designing optical devices like photodetectors or, in general, in any case where efficient control of energy propagation directivity is of primary importance.

A submicron broadband surface-plasmon-polariton unidirectional coupler

“…They are believed to be promising candidates for constructing the next-generation ultracompact integrated photonic circuits13. To realize such potential, an essential issue is to excite SPPs effectively and to control the direction in which they are launched6714151617181920212223.…”

“…However, the SPP launching intensities to the two opposite directions are equal due to the excitation symmetry. In order to realize unidirectional excitation of SPPs6714151617181920212223, one possible choice is to excite two nanogrooves with different geometries together. Figure 1(a) shows the schematic diagram of the groove-doublet structure, including the geometrical parameters w 1 , h 1 , w 2 , h 2 of the two grooves and the groove separation d. Under normal incidence, each groove excites two equal SPPs to the opposite directions.…”

Transmission and reflection properties of two-dimensional finite metal crystals

“…In Figures 8 and 9 we present the reflection, transmission and absorption curves in dependence on the incident wavelength for the low and high filling factors and for the same other geometrical parameters as in Figures 3 and 4. It should be noted, that the horizontal spatial shift between two layers presented in [24] was introduced in order to modify the horizontal propagation direction of surface plasmon polaritons in the near field of the structure. However, in the case considered here, this shift is symmetric with respect to the horizontal x-direction.…”

Noncentrosymmetric plasmon modes and giant terahertz photocurrent in a two-dimensional plasmonic crystal

“…The metal grating couples light to the surface-plasmon polaritons on the metal surface since the reciprocal wave vectors of the periodic grating ensure the momentum conservation between the incident light and the surface-plasmon polaritons. In case of a diffraction * FateevDV@yandex.ru grating with a broken symmetry [15][16][17][18][19], the excited plasmon polaritons are predominantly unidirectional and can effectively drag the free carriers, which results in a net photocurrent [14].…”