It contains links to the contemporary mathematical and scientific literature. I describe some of the chance events in and that led to my three-year immersion in this study, in which I was guided by both mathematics and physical experimentation. I owe special thanks to the architect Peter Pearcewho in demonstrated for me his concept of saddle polyhedron.
Hence, it can be seen that the behavior of the refractive index is dependent on the association of these two parameters, as well as their quantitative values.
This ability then allows for intentional determination of the refractive index. For example, inVictor Veselago analytically determined that light will refract in the reverse direction negatively at the interface between a material with negative refractive index and a material exhibiting conventional refractive index.
Therefore, his work was ignored for three decades. However, in each of these cases permeability remains always positive. But the inherent drawback is they are difficult to find above terahertz frequencies. In any case, a natural material that can achieve negative values for permittivity and permeability simultaneously has not been found or discovered.
Hence, all of this has led to constructing artificial composite materials known as metamaterials in order to achieve the desired results. A metamaterial developed to exhibit negative-index behavior is typically formed from individual components. Each component responds differently and independently to a radiated electromagnetic wave as it travels through the material.
Since these components are smaller than the radiated wavelength it is understood that a macroscopic view includes an effective value for both permittivity and permeability.
This material exhibited unusual physical properties that had never been observed in nature. These materials obey the laws of physicsbut behave differently from normal materials.
In essence these negative-index metamaterials were noted for having the ability to reverse many of the physical properties that govern the behavior of ordinary optical materials.
Until the demonstration of negative refractive index for microwaves by the UCSD team, the material had been unavailable.
Advances during the s in fabrication and computation abilities allowed these first metamaterials to be constructed.
Thus, the "new" metamaterial was tested for the effects described by Victor Veselago 30 years earlier. Studies of this experiment, which followed shortly thereafter, announced that other effects had occurred.
To achieve a negative index of refraction, however, permittivity with negative values must occur within the same frequency range.
The artificially fabricated split-ring resonator is a design that accomplishes this, along with the promise of dampening high losses.
With this first introduction of the metamaterial, it appears that the losses incurred were smaller than antiferromagnetic, or ferromagnetic materials. At demonstrated frequencies, pulses of electromagnetic radiation moving through the material in one direction are composed of constituent waves moving in the opposite direction.
The design was such that the cells, and the lattice spacing between the cells, were much smaller than the radiated electromagnetic wavelength.
Hence, it behaves as an effective medium. Furthermore, the characteristic of negative effective permeability evinced by this medium is particularly notable, because it has not been found in ordinary materials.
In addition, the negative values for the magnetic component is directly related to its left-handed nomenclature, and properties discussed in a section below. The split-ring resonator SRRbased on the prior theoretical article, is the tool employed to achieve negative permeability.
This first composite metamaterial is then composed of split-ring resonators and electrical conducting posts. In addition, early NIMs were fabricated from opaque materials and usually made of non-magnetic constituents.
As an illustration, however, if these materials are constructed at visible frequenciesand a flashlight is shone onto the resulting NIM slab, the material should focus the light at a point on the other side.
This is not possible with a sheet of ordinary opaque material. More recently as of [update]layered "fishnet" NIM materials made of silicon and silver wires have been integrated into optical fibers to create active optical elements. There are two requirements to achieve a negative value for refraction.
Second, negative values for both permittivity and permeability must occur simultaneously over a common range of frequencies. These are designed to resonate at designated frequencies to achieve the desired values.
Looking at the make-up of the split ring, the associated magnetic field pattern from the SRR is dipolar. Atoms exist on the scale of picometers. The splits in the rings create a dynamic where the SRR unit cell can be made resonant at radiated wavelengths much larger than the diameter of the rings.
If the rings were closed, a half wavelength boundary would be electromagnetically imposed as a requirement for resonance. It is there to generate a large capacitancewhich occurs in the small gap. This capacitance substantially decreases the resonant frequency while concentrating the electric field.
The individual SRR depicted on the right had a resonant frequency of 4.TMS discusses the fantastic science of the Star Wars movies, as well as TMS members ideas on building some Star Wars weapons. In this thesis photonic crystals are implemented as planar photonic crystals, i.e., optically thin semiconductor films with periodic arrays of holes etched into them, with a hole-to-hole spacing of the order of the wavelength of light in the dielectric media.
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SongLin Zhuang University of Shanghai for Science and Technology, China. Professor SongLin Zhuang, was born in In , he was selected as .
IntroductionThere have been numerous published reviews in recent years on the subject of tunneling time,,,,,,,,,.Indeed, this journal published one such review less than 2 years ashio-midori.com the profusion and currency of reviews on the subject, one might question the .
The surface mode exists at a metal-dielectric interface as surface plasmon (1) or at a photonic crystal surface terminated properly (34; 35; 36).
Besides its prominent near-filed properties, it can connect structures at its propagation surface and results in far-field effects.