Negative refraction through an impedance-matched left-handed metamaterial slab

Cataloged from PDF version of article.We report the transmission and reflection characteristics of a two-dimensional (2D) left-handed metamaterial (LHM). A well-defined left-handed (LH) transmission band with a peak value of −9.9 dB is obtained at frequencies where both effective permittivity and permeability are negative. A very sharp dip −38 dB at the reflection spectrum due to impedance matching at the surface of a 2D LHM is observed. Gaussian beam shifting experiments are performed to study the LH properties of a LHM structure. The structure has a negative refraction of electromagnetic waves in a certain frequency range. The negative refractive index values obtained for four different incident angles are in good agreement. © 2006 Optical Society of Americ

Directivity enhancement and deflection of the beam emitted from a photonic crystal waveguide via defect coupling

Cataloged from PDF version of article.We experimentally and numerically investigate the spatial distribution of the emission from a photonic crystal waveguide, coupled with defects, that are located at the output edge. Two defects that are located symmetrically enhance the directivity of the beam compared to that of a plain waveguide, as was reported in recently conducted theoretical work. We further demonstrate that a single defect deflects of the beam. By choosing the defect resonance that is close to the edge of the pass band of the waveguide, where the group velocity of the beam within the waveguide is slow, a significant amount of deflection can be achieved. (c) 2007 Optical Society of Americ

Oblique response of a split-ring-resonator-based left-handed metamaterial slab

Cataloged from PDF version of article.We experimentally studied the transmission response of a one-dimensional rectangle-prism-shaped metamaterial slab for oblique incidence angles. The electrical size of the split-ring resonators was 1 order of magnitude smaller than the operation wavelength similar to 8.5 cm. We demonstrated that the left-handed transmission peak preserved up to an angle of incidence 45 degrees. The angular measurements were performed with respect to two lateral directions. The confirmed insensitivity of split-ring-resonator-based metamaterials to the angle of incidence makes them a good candidate for superlens applications. (C) 2009 Optical Society of Americ

Electrically small split ring resonator antennas

Cataloged from PDF version of article.We studied electrically small resonant antennas composed of split ring resonators (SRR) and monopoles. The antennas considered have the same ring radius, but slightly different geometry. The resonance frequency depends on the geometry of the SRRs. Two SRR antennas are designed. The first one, which operates at 3.62 GHz, is demonstrated theoretically and experimentally. The size of this antenna is 0.095 lambda(0)x0.100 lambda(0) and is low profile at the other dimension. The gain and directivity of the antenna was 2.38 and 5.46, respectively. The corresponding efficiency was 43.6%. The estimated radiation Q (rad Q=23.03) was much larger than the minimum radiation Q (min Q=1.78). The second one is a rather small SRR antenna in which the capacitance between the rings is increased. The size is reduced to 0.074 lambda(0)x0.079 lambda(0). This structure is called serrated SRR (SSRR). Both antennas have similar far-field patterns but the efficiency of the SSRR antenna is less. (c) 2007 American Institute of Physics

Metamaterial inspired enhanced far-field transmission through a subwavelength nano-hole

In the present study, we first demonstrate the polarization and orientation dependent transmission response of split ring resonators at the infrared and visible band. Then, we numerically demonstrate a configuration for the enhancement of power passing through an electrically small hole. By using deep subwavelength optical split ring resonator antennas and couplers we achieved a 400-fold enhanced transmission from a subwavelength aperture area of the electrical size Λ 2/25. The power was transmitted to the far field with 3.9 dBi directivity at 300 THz. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Transmission through a subwavelength aperture at the optical regime is quite low. The Letter by Alici and Ozbay shows how it can be enhanced and transferred to the far field by using a metamaterial inspired configuration composed of nano-scale split ring resonator antennas and couplers. A 400-fold power enhancement was achieved. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Highly directional emission from photonic crystals with a wide bandwidth

Cataloged from PDF version of article.The authors numerically and experimentally demonstrated highly directional emission from photonic crystals. This was achieved by first splitting the incident electromagnetic wave into multiple beams using photonic crystal waveguide structures. The beams were then emitted out of the surface of a photonic crystal with the same phase, which resulted in a highly directional radiation pattern. The measured half power beam width was 4.8 degrees, which was in good agreement with the calculated value of 4.1 degrees. In contrast to the traditional beaming structures, their design did not involve gratinglike structures, which resulted in a wider operation bandwidth. (c) 2007 American Institute of Physics

Subwavelength resolution with a negative-index metamaterial superlens

Cataloged from PDF version of article.Negative-index metamaterials are candidates for imaging objects with sizes smaller than a half-wavelength. The authors report an impedance-matched, low loss negative-index metamaterial superlens that is capable of resolving subwavelength features of a point source with a 0.13 lambda resolution, which is the highest resolution achieved by a negative-index metamaterial. By separating two point sources with a distance of lambda/8, they were able to detect two distinct peaks on the image plane. They also showed that the metamaterial based structure has a flat lens behavior. (c) 2007 American Institute of Physics

Transmission spectra and the effective parameters for planar metamaterials with omega shaped metallic inclusions

Cataloged from PDF version of article.Planar metamaterials with omega shaped metallic inclusions were studied experimentally and theoretically. Our results show that when the incidence is perpendicular to the plane of the omega structure, the omega medium acts effectively as an electric resonator metamaterial. The stop band of the omega medium is due to the negative part of the electric resonance of the omega structure. The transmission band of the composite metamaterial (CMM) that is based on the omega medium is due to the strong positive part of the electric resonance of the omega structure. Consequently, the transmission band of the CMM does not coincide with the stop band of the omega medium. Furthermore, the transmission band of the CMM is a band with positive refractive indices. Our experimental and numerical results are in good agreement. (C) 2010 Elsevier B.V. All rights reserved

Observation of negative refraction and negative phase velocity in left-handed metamaterials

Cataloged from PDF version of article.We report the transmission characteristics of a two-dimensional (2D) composite metamaterial (CMM) structure in free space. At the frequencies where left-handed transmission takes place, we experimentally confirmed that the CMM structure has effective negative refractive index. Phase shift between consecutive numbers of layers of CMM is measured and phase velocity is shown to be negative at the relevant frequency range. Refractive index values obtained from the refraction experiments and the phase measurements are in good agreement. (C) 2005 American Institute of Physics