A negative-index metamaterial design based on metal-core, dielectric shell resonators

Abstract

Abstract-In this paper a simple effective-media analysis (including higher-order multipoles) is used to design a singleresonator, negative-index design based on a metal-core, dielectric-shell (MCDS) unit cell. In addition to comparing the performance of the MCDS design to other core-shell negativeindex designs, performance trade-offs resulting from the relative positioning of the electric and magnetic modal resonances in the MCDS design are also discussed.

Perturbation Theory in the Design of Degenerate Rectangular Dielectric Resonators

“…With the extra degree of freedom associated with the lattice arrangement (versus the single-resonator response), it is possible, for example, to achieve negative index in the tail regions of the two resonances where the losses are lower. While results showing packing effects on the loss performance of degenerate all-dielectric resonator designs will be presented in a follow-on effort, increases in the packing fraction is shown to decrease the loss associated with a metal-core, dielectric-shell spherical design in [16].…”

“…Well-known approaches that have been used to attempt to align the resonances of all-dielectric resonators include the core-shell designs of [15,16] and the AB-type designs of [17,18]. While both of these methods introduce an additional degree of freedom that provides for the tuning of the resonances (in [15,16] by introducing a surrounding dielectric shell layer to a dielectric core and in [17,18] by introducing an additional resonator particle into the unit cell), unfortunately these two approaches can easily bring into question the applicability of effective media; this becomes particularly apparent at higher operating frequencies.…”

“…While both of these methods introduce an additional degree of freedom that provides for the tuning of the resonances (in [15,16] by introducing a surrounding dielectric shell layer to a dielectric core and in [17,18] by introducing an additional resonator particle into the unit cell), unfortunately these two approaches can easily bring into question the applicability of effective media; this becomes particularly apparent at higher operating frequencies. In the case of the AB-type design, the size of the unit cell is physically extended (perhaps by a factor of two) to accommodate the additional resonator while, alternatively, in the core-shell design the electrical size of the resonator is forced to increase because overlap of only higher-order modes is possible.…”

Ewald method for 3D periodic dyadic Green's functions and complex modes in composite materials made of spherical particles under the dual dipole approximation

“…We consider microspheres with radius r = 1 μ m made of PbTe, with permittivity ε m = 32.04 + 0.0524 i [ Basilio et al , 2011; Palik , 1985], and with r = 52 μ m made of TiO 2 , with permittivity ε m = ε ′ m + i ε ″ m , where ε ′ m = 3.33 f + 92.34 and ε ″ m = 0.28 f 2 + 7.64 f − 1.54, with f being the frequency in THz [ Berdel et al , 2005; Lannebere , 2011]. PbTe microspheres resonate at infrared frequencies between 20 THz and 40 THz, and TiO 2 microspheres resonate at millimeter waves between 200 GHz and 500 GHz.…”