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Since the ancient Greek era, several theories of the nature of light have been postulated. The Greek philosopher Aristotle and his contemporaries first attempted to explain how the sensation of vision is caused and how light comes to earth from the sun or the stars. They were also concerned with the nature of light and the mechanism of vision. However, their postulates on the nature of light, due to the lack of experiments, were only of philosophical character and they were not able to formulate a systematic theory of light capable of explaining the optical phenomena involved in the propagation of light or the interaction of light and matter.

As a preliminary to a detailed study of the reactions of certain body tissues to electromagnetic radiations on centimetre wave-lengths, it has been found desirable to determine the propagation characteristics of such waves in various parts of the body.

A cylindrical plasma column placed across a waveguide or situated in free space in such a fashion that the electric field of an incoming wave is perpendicular to the axis of the column displays a series of resonant responses constituting a reflection and absorption spectrum. The spectrum may be elicited and observed at a fixed microwave frequency by varying the current through the column on which the incoming wave impinges and noting the reflected power. The present paper discusses (1) the electromagnetic field associated with the assumed electronic motion for the principal member of the spectrum and (2) the effect of radiation damping on the Q for this member.

Remote detection consists of picking up signals reflected or emitted by water, rocks, plants, or clouds; whether perceived or not by the senses of man. All objects reflect to a greater or lesser extent the radiation emitted by the Sun, or any other source of energy. All objects, provided their temperature is above absolute zero (0 K, −273°C) emit radiations part of which can be perceived by special instruments.

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A new shape of metamaterials and actuation mechanism are proposed and demonstrated. This reconfigurable metamaterials was constructed by electric split-ring resonators. The experimental results show this device reveals polarization dependence and blue shifting of spectrum.

We present some of our recent experiments and numerical calculations on photonic metamaterials. In particular, we demonstrate negative-index metamaterials, simultaneous negative phase and group velocity of light, magnetization waves in negative-index metamaterials, and circular dichroism at optical frequencies.

This paper presents an accurate method to analyze frequency selective surfaces (FSSs) illuminated by a non-uniform electromagnetic field.

The influence of negative permittivity and permeability on the scattering patterns for dielectric and metamaterial posts is presented. Combination of an extended iterative scattering procedure and the orthogonal expansion method is used to investigate oblique scattering of an electromagnetic plane wave from an arbitrary configuration of parallel circular cylinders.

We demonstrate metamaterial with a cubic optical nonlinearity that is ten orders of magnitude greater than the reference nonlinearity of CS2. The nonlinearity has optomechanical nature and is underpinned by light-induced electromagnetic near-field interactions.

Electromagnetic cloaks are devices that make objects undetectable for probing with electromagnetic waves. The known realizations of transformational-optics cloaks require materials with exotic electromagnetic properties and offer only limited performance in narrow frequency bands. Here, we demonstrate a wideband and low-loss cloak whose operation is not based on the use of exotic electromagnetic materials, which are inevitably dispersive and lossy. Instead, we use a simple structure made of metal layers. In this Letter, we present an experimental demonstration of cloaking for microwaves and simulation results for cloaking in the visible range.

Metamaterial active in the terahertz (THz) frequency region is very attractive due to its potential for building unique optical components, such as superlenses, using relative simple fabrication technique. The meta-atom, an elementary unit of the metamaterial, is an electromagnetic resonator with non-zero magnetic and/or electric dipole interacting with free space electromagnetic wave. All present THz metamaterial studies are performed in the far-field, thereby overlooking the details of the interaction between the electromagnetic field and the meta-atoms. On the other hand, comprehensive knowledge of this interaction is required for the design of the active metamaterial.

We demonstrate gradient index optics for terahertz radiation based on passive and active metamaterials. Furthermore, we experimentally investigate the tailored focusing of a highly confined terahertz surface wave on a gradient index meta-surface.

Metamaterials have ignited a world-wide flurry of research based in part on the realization of negative refractive index, and the idea of coordinate-transformation design of materials leading to exotic phenomena such as electromagnetic cloaking or energy concentration. The implementation of such ideas is exciting, but is most likely a long-term proposition in terms real-world applications. Briefly, metamaterials are sub-wavelength composites where the electromagnetic response originates from oscillating electrons in highly conducting metals such as gold or copper allowing for a design specific resonant response of the electrical permittivity or magnetic permeability. This is especially important for the technologically relevant terahertz frequency regime where there is a strong need to create components to realize applications ranging from spectroscopic identification of hazardous materials to noninvasive imaging. Our work has been focusing on the development of functional THz metamaterial structures and devices using MEMS technologies, which show extreme power at the micro scale level.

We demonstrate structurally reconfigurable metamaterials with a marked tunability of both electric and magnetic responses at terahertz frequencies where artificial “atoms” reorient within unit cells in response to an external stimulus.

We review different structures for microwave and optical range containing 'left-handed' metamaterials - artificial composites with simultaneously negative effective permittivity and permeability. Special attention is dedicated to their fundamentals, design strategies and main applications which include subwavelength resonant cavities, superlenses, etc.

A modified Snell's law for light rays in uniformly moving isotropic dielectrics is discussed for the case when the velocity of the medium is parallel to the medium-vacuum interface. The direction of the ray in the moving medium is found by using an expression for the magnetic field obtained in a previous work, in the expression for the Poynting vector. The dielectric is assumed nondispersive.

The plane-wave reflection and transmission coefficients of a dielectric slab having a sinusoidal variation of its permittivity are deduced from the solution of the full electromagnetic boundary-value problem and compared with the results of the approximate procedure based on the coupled-mode equations for the slowly varying amplitudes.

Analytical expressions obtained from electromagnetic field theory are used to plot propagated ray paths as functions of frequency and launch angle. From these plots the dispersive effects are predicted for signals transmitted between any two selected points.

CONVENTIONAL prism monochromators have two main limitations: a limited resolution due principally to the finite size of the prism; and impurity of spectrum owing to light scattered from various optical components, particularly the prism. A great improvement in these two respects can be obtained by a simple method which converts a single-monochromator into a double- or multiple-monochromator.

THE free-space phase velocity of microwaves of length 1.25 cm. and frequency 24,000 Mc./s. has been measured by a new method.

The problems of electromagnetic waves in moving isotropic or uniaxial mediums have been dealt with by numerous authors. Chawla and Unz considered the fields in a moving anisotropic plasma, and Chen and Cheng analyzed waves in an isotropic plasma in a moving dielectric medium. In this note we consider electromagnetic fields in a moving anisotropic medium and propose the network formulation of electromagnetic fields in the moving medium in the radial cylindrical coordinate. The method is an extension of the transmission line representation of electron beams on infinite magnetic fields. We can apply these results to the cases of any magnetic field intensity and, further, solve the complex problems for a stationary anisotropic plasma by a similar method.

Angular spectrum representation is derived for the electromagnetic field scattered from any linear, time-independent medium. In particular, the medium may be homogeneous or inhomogeneous, isotropic or anisotropic, spatially nondispersive or spatially dispersive, and it may be dielectric, magnetic, or magnetoelectric. The spectral amplitudes of the plane-wave modes of the scattered field are found to depend in a relatively simple manner on the induced polarization and on the induced magnetization. In the special case when the first Born approximation applies, the results take a particularly simple form and may be used to determine the scattered electromagnetic field vectors at any distance from the scatterer.

This communication refers the reader to a report where we have studied the effect of atmospheric winds on the frequency spectrum of an electromagnetic wave.

A standard photographic film was proved to be applicable to a quick and easy direct mapping of an electromagnetic field. The method utilises selective development of the film in accordance with the thermo-image produced by the electromagnetic field. The method would be most useful for preparing microwave holograms.

SIR J. J. THOMSON1 has suggested that a photon is a finite, harmonic train of circular lines of electric force originating when an electron in a radiating atom falls from one energy-level to another. Such circular lines of force would move at right angles to their planes, and their centres would travel along a straight line with the velocity of light. If a set of electromagnetic waves of the kind suggested could exist, the energy in any wave-front could be concentrated around the axis of propagation, so that the radiation could be confined within a cylindrical pencil and would not be dissipated through space. The photon would therefore travel unchanged without loss of energy.