Influence of finite conductivity on the excitation of phase resonances in metallic surfaces with cavities of circular cross sections

Abstract

Phase resonances have been investigated in the last few years, not only because of their striking features, such as extremely high quality factor and huge enhancement of the electromagnetic field inside cavities/grooves, but also for their promising applications. However, taking into account that these resonances are more efficiently excited in highly conducting structures, most of the studies have been devoted to explore this phenomenon at wavelengths in the infrared or larger, using different approaches for the boundary conditions. In this paper, we investigate the validity of the perfect conductor approximation and the surface impedance boundary condition to appropriately represent the electromagnetic response of a metallic surface comprising a finite number of subwavelength cavities of circular cross sections. Far- and near-field plots are shown and analyzed in order to investigate the validity ranges and discuss to what extent phase resonances can be excited at shorter wavelengths in these structures.