We report on the fabrication, through photolithography techniques, and the detailed characterization, through direct transmission measurements, of a periodic system composed of five layers of photolithographically aligned micrometer-sized Ag split-ring resonators (SRRs). The measured transmission spectra for propagation perpendicular to the SRRs plane show a gap around 6 THz for one of the two possible polarizations of the incident electric field; this indicates the existence of a magnetic resonance, which is verified by detailed theoretical analysis. To our knowledge this is the first time that a system of more than one layer of micrometer-sized SRRs has been fabricated. The measured optical spectra of the Ag microstructure are in very good agreement with the corresponding theoretical calculations.

Using numerical simulation techniques such as the transfer matrix method and the commercially available code Microwave Studio, we study the transmission properties of left-handed (LH) metamaterials and arrays of split-ring resonators (SRRs). We examine the dependence of the transmission through single-and double-ring SRRs on parameters of the system such as the size and shape of the SRRs, size of the unit cell, dielectric properties of the embedding medium where the SRRs reside, and SRR orientation relative to the incoming electromagnetic field. Moreover, we discuss the role of SRRs and wires on the electric cut-off frequency of the combined system of wires and SRRs, as well as the influence of the various system parameters on the LH transmission peak of a medium composed of SRRs and wires. Finally, demonstrating the disadvantages of the currently used SRR designs due to the lack of symmetry, we discuss more symmetric, multigap SRRs, which constitute very promising components for future two-dimensional and three-dimensional LH structures.

Using transmission and reflection measurements in a five layer micrometer-scale split-ring resonator ͑SRR͒ system, fabricated by a photolithography procedure, the authors demonstrate the occurrence of a negative magnetic permeability regime in that system at ϳ6 THz. The transmission and reflection were measured using oblique incidence, resulting to a magnetic field component perpendicular to the SRR plane, which excites the resonant circular currents constituting the magnetic resonance.

The effect of conductivity variation as a proposed method for the investigation of photoconductive switching properties of split ring resonators (SRRs) is simulated. Three different systems that are applicable under certain fabrication and/or optical excitation conditions are described. The simulated transmission spectrum indicates that for a large range of dark conductivity values, complete switching of the SRR resonance is possible. One of the simulated systems, involving split ring resonators on Si substrate, was fabricated and characterized. The transmission spectrum of that system was measured, with the Si in its high-resistivity state, and a À60 dB dip between 108 and 115 GHz, due to SRRs magnetic resonance, was observed. . These materials exhibit the unique physical property of having both negative electrical permittivity (e) and negative magnetic permeability (m) over a common frequency band. Left handed metamaterials generated a great interest, partly due to the properties of these materials which are not observed in naturally occurring materials. These include negative refractive index, artificial magnetism, super focusing, and reduced lens aberrations [1][2][3][4][5]. Since the first demonstration of LH metamaterials [4], different structures that exhibit equivalent properties have been proposed [6]; however the initial structure consisting of the periodic arrangement of split ring-resonators (SRRs) and metallic wires remains the mostly studied. The wires provide the negative electric permittivity, (e), [7] whereas the SRRelements generate the negative magnetic permeability (m) response [2]. The SRR consists of metallic rings with gaps that act like a capacitor-inductor (LC) circuit when a magnetic field component is perpendicular to their plane. Due to the resonant circular currents in the rings they exhibit a resonance at v m = 1/(LC) 1/2 associated with resonant circular currents in the SRR rings [8][9][10]. It was also demonstrated that besides for a magnetic field that is perpendicular to the SRR plane, the existence of an electric field parallel to the gaps of the SRR can couple to the magnetic resonance and excite an oscillating resonant current around the rings. This phenomenon is described as

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