Spatial dispersion in two-dimensional plasmonic crystals: Large blueshifts promoted by diffraction anomalies

Abstract

We develop a methodology to incorporate nonlocal optical response of the free electron gas due to quantuminteraction effects in metal components of periodic two-dimensional plasmonic crystals and study the impact of spatial dispersion on promising building blocks for photonic circuits. Within the framework of the hydrodynamic model, we observe significant changes with respect to the commonly employed local-response approximation, but also in comparison with homogeneous metal films where nonlocal effects have previously been considered. Notable are the emergence of a contribution from nonlocality at normal incidence and the surprisingly large structural parameters at which finite blueshifts are observable, which we attribute to diffraction that offers nonvanishing in-plane wave vector components and increases the penetration depth of longitudinal (nonlocal) modes.

On quantum approach to modeling of plasmon photovoltaic effect

“…(47)). It is noteworthy that the hydrodynamic theory allows fully retarded calculations for not only spherical particles as reviewed here, but also planar geometries (nonlocal Fresnel coefficients) [71] and even regular two-dimensional particle layers [26]. Although the presented quantum phenomena are highly localized they can have a strong impact on a larger particle or system in the interplay with long-range retardation effects.…”

“…Efforts to extend the original formulation of light scattering by a sphere by Gustav Mie [19] which excludes electro-optical bulk and surface effects of the conduction band electrons are made since the 1980s [60][61][62][63][64]. Advanced material models can be derived from perturbative theories [23,51], by separating the free electron dynamics from the core electron polarization via the hydrodynamic equation for an electron plasma [22][23][24][25][26][65][66][67][68][69][70][71][72][73] and from microscopic theories [30,36,74]. It was shown within the hydrodynamic framework that the electron spill-out can be adequately incorporated [75].…”

“…These waves primarily create additional damping channels, however, they also yield resonant enhancement effects [26,71].…”

“…In recent years, a great effort to theoretically [22][23][24][25][26][65][66][67][68][69][70][71][72][73] describe and subsequently to experimentally [55][56][57]59] verify the effect of spatial dispersion in metals was made. In the hydrodynamic approach, coupling the electromagnetic wave equation…”

“…Furthermore, we discuss the modification of Mie coefficients to include spatial dispersion effects of electrons interacting with each other over short distances. Such nonlocal effects are introduced in the framework of the hydrodynamic model [22][23][24][25][26].…”