We investigate numerically the limits of the resonant magnetic response with a negative effective permeability mu(eff) for single-ring multicut split-ring resonator (SRR) designs up to optical frequencies. We find the breakdown of linear scaling due to the free electron kinetic energy for frequencies above approximately 100 THz. Above the linear scaling regime, the resonance frequency saturates, while the amplitude of the resonant permeability decreases, ultimately ceasing to reach negative value. The highest resonance frequency at which mu(eff) < 0 increases with the number of cuts in the SRR. A LC circuit model provides explanation of the numerical data.

We demonstrate experimentally and numerically that metamaterials based on bilayer cross wires give giant optical activity, circular dichroism, and negative refractive index. The presented chiral design offers a much simpler geometry and more efficient way to realize negative refractive index at any frequency. We also developed a retrieval procedure for chiral materials which works successfully for circularly polarized waves

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We study both theoretically and experimentally the transmission properties of a lattice of split ring resonators (SRRs) for different electromagnetic (EM) field polarizations and propagation directions. We find unexpectedly that the incident electric field E couples to the magnetic resonance of the SRR when the EM waves propagate perpendicular to the SRR plane and the incident E is parallel to the gap-bearing sides of the SRR. This is manifested by a dip in the transmission spectrum. A simple analytic model is introduced to explain this interesting behavior.Comment: 4 pages, 4 figure

Recent advancements in metamaterials andMetamaterials and plasmonics, two branches of the study of light in electromagnetic structures, have emerged as promising scientific fields. Metamaterials are engineered materials that consist of subwavelength electric circuits replacing atoms as the basic unit of interaction with electromagnetic radiation 1-3 . They can provide optical properties that go beyond those of natural materials, such as magnetism at terahertz and optical frequencies 4-6 , negative index of refraction 7-9 , or giant chirality 10 . Plasmonics exploits the mass inertia of electrons to create propagating charge density waves at the surface of metals [11][12] , which may be useful for intrachip signal transmission, biophotonic sensing applications, and solar cells, amongst others [13][14][15] .

We investigate, both theoretically and experimentally, a left-handed metamaterial design composed of pairs of short slabs connected with continuous wires, operating in microwave frequency regime. The design was found to give left-handed behavior for a wide range of structure parameters, maintaining high impedance match with free space. We introduce a capacitor-inductor circuit description of the design and we show that this description can account for all the characteristics of its electromagnetic behavior, explaining also its superior performance.

We analyze the transmission and reflection data obtained through transfer matrix calculations on metamaterials of finite lengths, to determine their effective permittivity ǫ and permeability µ. Our study concerns metamaterial structures composed of periodic arrangements of wires, cut-wires, split ring resonators (SRRs), closed-SRRs, and both wires and SRRs. We find that the SRRs have a strong electric response, equivalent to that of cut-wires, which dominates the behavior of left-handed materials (LHM). Analytical expressions for the effective parameters of the different structures are given, which can be used to explain the transmission characteristics of LHMs. Of particular relevance is the criterion introduced by our studies to identify if an experimental transmission peak is left-or right-handed. PACS: 41.20.Jb, 42.70.Qs, 73.20.Mf Recently, there have been many studies about metamaterials that have a negative refractive index n. These materials, called left-handed materials (LHMs), theoretically discussed by Veselago [1], have simultaneously negative electrical permittivity ǫ and magnetic permeability µ. Such materials consisting of split ring resonators (SRRs) and continuous wires were first introduced by Pendry [2,3], who suggested that they can also act as perfect lenses [4].Since the original microwave experiment by Smith et al. [5], which first materialized Pendry's proposal, various new samples were prepared [6,7] (composed of SRRs and wires) all of which have been shown to exhibit a pass band in which it was assumed that ǫ and µ are both negative. This assumption was based on measuring independently the transmission, T , of the wires alone, and then the T of the SRRs alone. If the peak in the combined metamaterial composed of SRRs+wires were in the stop bands for the wires alone (which corresponds to negative ǫ) and for the SRRs alone (which is thought to correspond to negative µ) the peak was considered to be lefthanded (LH). Further support to this interpretation was provided by the demonstration that some of these materials exhibit negative refraction of electromagnetic waves [8]. Subsequent experiments [9] have reaffirmed the property of negative refraction, giving strong support to the interpretation that these metamaterials can be correctly described by negative permittivity and negative permeability. However, as we shall show in the present study, this is not always the case. The combined system of wires and SRRs exhibits synergy of the two components as a result of which its effective plasma frequency, ω ′ p , is much lower than the plasma frequency of the wires, ω p . There is also a significant amount of numerical work [10][11][12][13] in which the complex transmission and reflection amplitudes are calculated for a finite length of metamaterial. Using these data a retrieval procedure can then be applied to obtain the effective permittivity ǫ and permeability µ, under the assumption that the metamaterial can be treated as homogeneous. This procedure confirmed [14,15] that a medium composed...

Toroidal multipoles are the terms missing in the standard multipole expansion; they are usually overlooked due to their relatively weak coupling to the electromagnetic fields. Here, we propose and theoretically study all-dielectric metamaterials of a special class that represent a simple electromagnetic system supporting toroidal dipolar excitations in the THz part of the spectrum. We show that resonant transmission and reflection of such metamaterials is dominated by toroidal dipole scattering, the neglect of which would result in a misunderstanding interpretation of the metamaterials' macroscopic response. Because of the unique field configuration of the toroidal mode, the proposed metamaterials could serve as a platform for sensing or enhancement of light absorption and optical nonlinearities.