Igor V. Minin

Comments on “Focusing Characteristics of Curvilinear Half-Open Fresnel Zone Plate Lenses: Plane Wave Illumination”

For original paper by Hristov et al., see IEEE Trans. Antennas Propag., vol.53, p.1912-19 (2005 June)

Terajet from 3D anisotropic artificial metamaterial

A dielectric anisotropic metamaterial-based cuboid (metacuboid) for terajet formation are proposed. Artificial metamaterials based on metallic photonic crystal with high metal filling factor and perforated dielectric are discussed. The optical responses of meta-coboids are described by the effective medium approximation, in which the dielectric permittivity tensor is diagonal with different values of permittivities. The metacuboids has been designed to operate as a focusing device producing a terajet in the homogenization regime. The dispersions of effective permittivity formed by different types of structures were analytically obtained for both metamaterial and photonic crystal regimes. The terajet formation and beam focusing with birefringer effect were numerically and experimentally shown.

Explosive Pulsed Plasma Antennas for Information Protection

Since the discovery of radio frequency (RF) transmission, antenna design has been an integral part of virtually every communication and radar application. In its most common form, an antenna represents a conducting metal surface that is sized to emit radiation at one or more selected frequencies. Antennas must be efficient so the maximum amount of signal strength is expended in the propogated wave and not wasted in antenna reflection. The modern requirements to antenna include compactness and conformality, rapid reconfigurability for directionality and frequency agility and should also allow low absolute or out-of-band radar cross-section and facilitate low probability of intercept communications. The need for an antenna that is invisible (thus not detectable while not in operation) has, already in the 1980s, sparked work on the feasibility of using an atmospheric discharge plasma1 as an RF antenna. Moreover, data communications can be made more secure if the antenna only exists during the transmission of each data packet. Such antennas use plasma formations as the receiver or transmitter elements. The characteristics of the plasma formations are determined by purpose of the specific antenna. Plasmas have two important properties that are relevant for interaction with electromagnetic waves: • For frequencies above the plasma frequency, a semi-infinite plasma transmits EM waves with a wavelength, l /e r where l is the free space wavelength. Thus plasmas can in principle be used for electronic tuning or control of a radiation pattern by varying the plasma density. For the densities typical of discharge tubes, this phenomenon appears especially useful at microwave frequencies. • For frequencies below the plasma frequency, however, the dielectric constant is e r < 0, the plasma behaves as a metal, free space EM waves cannot penetrate, and are reflected. Radio communications via the ionosphere rely on this effect. Plasma technology can be utilized to create secure WiFi data transmission capability for use in different applications up to 100 GHz [33]. WiFi has enabled a wide array of inexpensive communication devices that are utilized in desk-top computing, networking, PDA’s etc. Its

Calculation Experiment Technology

There are two common approaches for numerical solution of continuum equations in mechanics: Lagrangian and Eulerian. The choice usually depends on exploiting specific features of these approaches that are suitable for the problem at hand. In the Lagrangian approach the computational grid that discretizes the domain deforms with the material. However Lagrangian method is not suitable for applications involving large distortion and large rotation, or for cases where boundary itself is modified as the solution proceeds. On the other hand, in the Eulerian approach the computational grid is fixed in space. The material moves through this grid as it flows and deforms. Even though large distortions are handled easily in this method, interface tracking and contact surface algorithms pose considerable difficulty. Novel methods have been developed that discretize the continuum domain by discrete Lagrangian particles. Harlow’s Particle In Cell (PIC) method [1] may be considered to be one of the precursors. This method eliminates the shortcomings of the traditional Lagrangian and Eulerian methods while retaining the good aspects of them. This method allows one to solve a broader class of problems by allowing large distortions and efficient calculation at interfaces. The PIC method also allows precise distinction of material boundaries. In spite of these advantages the PIC method shows certain limitations for problems where variables are history dependent, for example in elasto-plasticity, viscoelasticity, various relaxation processes, and for problems dealing with low pressures. Another shortcoming of this approach is that the solution fluctuates due to the method of discretization of mass, energy and momentum, and the way by which density is calculated. A more serious limitation arises out of the complexity of pressure calculation in a mixed cell. From the above mentioned of existing computational methods for non-stationary continua it is clear that none of them satisfy the requirements for large-scale computation. The grid and particle methods such as PIC and GAP [2] seem to possess the best characteristics in this regard. Hence these methods were taken up as a basis for developing a new method – the method of individual particles (1979, developed under the scientific leaderships of Prof. V.F.Minin) to extend the areas of applicability of the particle methods. Some particle methods in Astrophysical Fluid Dynamics are discussed and available at [3].

Theoretical and experimental investigations of photonic jet array from rectangle phase diffraction grating

The generations of photonic jet array using rectangle phase diffraction grating at visible light region are demonstrated numerically and experimentally for the first time. The power flow patterns for the rectangle diffraction grating are simulated by using the finite-difference time-domain method. In experiment, the rectangle phase diffraction grating was fabricated with polydimethylsiloxane material. The direct imaging of the spatial and amplitude features for the gratingassisted photonic jet array is performed with a scanning optical microscope system. The focusing qualities of photonic jet array are evaluated in terms of focal length and transversal width along propagation and transversal directions. The photonic jet array could be operated in a wide range application for nanotechnology, self-assembly, energy generation and storage materials through the rectangle phase diffraction grating.

Multielement emitters of terahertz radiation based on array of photonic jet

The paper presents a new approach of a THz multielement emitter based on lateral photo-Dember effect, consisting of periodic gold stripes deposited on the semiconductor surface in which periodic illumination is created using an array of mesoscale dielectric particles to form an array of photonic jets radiating the semiconductor surface with the metal mask.

Apparatus for liquid acoustic signal generation using self-sustained low-voltage electric discharge generator

The paper describe the device for generating acoustic signals in liquid with the absence of explosive in their design. The possibility of developing a stand-alone, compact, non-disposable low-voltage electrodischarge acoustic generator without sophisticated circuit tweaks, with low material and financial costs has been shown.

Brief review of acoustical (sonic) artificial lenses

The brief review of a modern state of art of acoustical artificial lens are observed. It has been shown that the subwavelength resolution in acoustical lens today may be achieved by metamaterial or artificial lens. It was mentioned that it is possible to obtain an acoustical analogue of photonic jet - acoustojet - to focus acoustical and sonic waves in subwavelength area by penetrable 3D mesoscale particle.

Diffractive Optics Microsensors

The term Microsensor is typically used to mean a sensing device that is fabricated using microelectronic technology. The field of Microsensors has a fifty-year history starting with several key developments in the 1950’s: uf0b7 The invention of integrated circuits. uf0b7 The discovery of piezoresistance in silicon. uf0b7 The discovery of selective etching of single-crystal silicon. uf0b7 The development of thin-film read heads for magnetic recording. During the last twenty years, emphasis in this field has gradually shifted from basic research on materials and process technologies toward product development. Each year new products appear, and with these, an expansion of potential future opportunities. Microsensors have a bright future, both in the commodity arena and in the MEMS-enabled arena. The physical sensors, pressure, acceleration, rotation, and acoustic (microphones) continue to find new commodity-level markets. Sensors, whether commodity sensors such as the cell-phone microphone, or system sensors, are becoming smarter, more capable, and are finding new markets every day. In the present review we describe a wide class of microsensors based on diffractive optics element (DOE). Diffractive optics is very versatile since any type of wave can be considered for computation within the computer. Digital holograms created with such technology are more commonly called DOE. Another name for DOE is computer-generated hologram (CGH). Because of these equivalent terminologies, the word DOE will be used in this chapter. For their operation the diffractive elements depend on diffraction effects: DOEs are based on the effect of radiation diffraction on a periodic or quasiperiodic structure rather than on refraction as it is in the classical optics. The optical depth of a focusing element ranges within a radiation wavelength. In this respect, the zone plates (FZP) like lens may be referred to diffraction elements, i.e., to a class of quasioptical focusing systems, since according to the definition of quasioptics they are calculated, as a rule, by laws of geometrical optics, and the principle of their operation is based on diffraction effects. There basic types of DQE are distinguished (according to the principle of their location relative to the direction of electromagnetic wave propagation) [1], they are: a transverse element (implemented primarily on a plane surface), a longitudinal-transverse element (on an arbitrary curved surface), and a longitudinal element (representing a set of screens situated along the direction of electromagnetic wave propagation). DQE can operate by the principle of “transmission” or “reflection”.

Diffractional antenna-radomes for radar sensors: a review

The mm-wave planar Fresnel Zone Plate (FZP) lens and antenna has the advantage of being a flat construction that is cheap, light, and easy to manufacture and have a low losses power in material. To increase the focusing efficiency, resolving and scanning properties of a flat mm-wave FZP lenses and antennas, to use an antenna surfaces as a radome and to create different shaped radiation patterns the construction of three-dimensional plate: ogival, spherical, parabolic, conical, etc., for the first time were development and investigated both theoretical and experimentally in mm-waves since 1981.