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.
“…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].…”
Section: Inclusion and Packingmentioning
confidence: 99%
“…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.…”
Section: Introductionmentioning
confidence: 99%
“…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.…”
Abstract-The design of resonators with degenerate magnetic and electric modes usually requires the ability to perturb one or both types of modes in order to induce alignment of magnetic and electric properties. In this paper perturbation theory is used to identify different types of inclusions that can be used to realize fundamentalmode degeneracy in a rectangular dielectric resonator and thus, can ultimately be used in the design of negative-index metamaterials. For reasons associated with fabrication in the infrared-frequency regime, rectangular resonator designs are of particular interest.
“…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].…”
Section: Inclusion and Packingmentioning
confidence: 99%
“…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.…”
Section: Introductionmentioning
confidence: 99%
“…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.…”
Abstract-The design of resonators with degenerate magnetic and electric modes usually requires the ability to perturb one or both types of modes in order to induce alignment of magnetic and electric properties. In this paper perturbation theory is used to identify different types of inclusions that can be used to realize fundamentalmode degeneracy in a rectangular dielectric resonator and thus, can ultimately be used in the design of negative-index metamaterials. For reasons associated with fabrication in the infrared-frequency regime, rectangular resonator designs are of particular interest.
“…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.…”
Section: Modes With Real or Complex Wave Number And Description Of Comentioning
[1] We derive the Ewald representation for the dyadic periodic Green's functions to represent the electromagnetic field in a three dimensional (3D) periodic array of electric and magnetic dipoles. Then we use the developed theory to analyze the modes with real and complex wave number in a 3D periodic lattice of lead telluride (PbTe) microspheres at infrared frequencies and in a 3D periodic lattice of titanium dioxide (TiO 2 ) microspheres at millimeter waves. Each microsphere is equivalently modeled with both an electric and a magnetic dipole, via a method here called the dual dipole approximation (DDA). The 3D lattices exhibit first a magnetic-induced then an electric-induced feature determined by microsphere magnetic and electric resonances. The DDA wave number results are compared to the ones computed with single electric or single magnetic dipole approximation and to the ones retrieved by using the Nicolson-Ross-Weir (NRW) retrieval method from reflection and transmission of finite thickness slabs computed by a full-wave simulation. It is shown that the DDA method is in very good agreement with NRW, in contrast to the previously reported single dipole approximation methods that fail to predict one of the two features (either electric or magnetic). A mode with transverse polarization is found to be dominant and able to propagate inside the lattice, and therefore the composite material can be treated as a homogeneous one with effective refractive index. This is obtained by adopting five different retrieval procedures for each lattice, and their agreement or disagreement is discussed.Citation: Campione, S., and F. Capolino (2012), Ewald method for 3D periodic dyadic Green's functions and complex modes in composite materials made of spherical particles under the dual dipole approximation, Radio Sci., 47, RS0N06,
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