Terahertz frequency superconductor-nanocomposite photonic band gap

2018 ◽  
Vol 32 (05) ◽  
pp. 1850056 ◽  
Author(s):  
Hussein A. Elsayed ◽  
Arafa H. Aly
Keyword(s):  
Volume Fraction ◽  
Photonic Band Gap ◽  
Fluid Model ◽  
Cutoff Frequency ◽  
Characteristic Matrix ◽  
Pass Filter ◽  
Two Fluid Model ◽  
Superconductor Material ◽  
High Pass ◽  
Photonic Band

In the present work, we discuss the transmittance properties of one-dimensional (1D) superconductor nanocomposite photonic crystals (PCs) in THz frequency regions. Our modeling is essentially based on the two-fluid model, Maxwell–Garnett model and the characteristic matrix method. The numerical results investigate the appearance of the so-called cutoff frequency. We have obtained the significant effect of some parameters such as the volume fraction, the permittivity of the host material, the size of the nanoparticles and the permittivity of the superconductor material on the properties of the cutoff frequency. The present results may be useful in the optical communications and photonic applications to act as tunable antenna in THz, reflectors and high-pass filter.

scholarly journals A Compact High-Pass Filter Using Hybrid Microstrip/Nonuniform CPW with Dual-Mode Resonant Response

2016 ◽  
Vol 2016 ◽  
pp. 1-7
Author(s):  
Hui Chen ◽  
Di Jiang ◽  
Ke-Song Chen ◽  
Hong-Fei Zhao
Keyword(s):  
Printed Circuit Board ◽  
Coplanar Waveguide ◽  
Cutoff Frequency ◽  
Circuit Board ◽  
Dual Mode ◽  
Pass Filter ◽  
High Pass Filter ◽  
Mode Characteristic ◽  
High Pass ◽  
Good Agreement

A novel and miniature high-pass filter (HPF) based on a hybrid-coupled microstrip/nonuniform coplanar waveguide (CPW) resonator is proposed in this article, in which the designed CPW has exhibited a wideband dual-mode characteristic within the desired high-pass frequency range. The implemented filter consists of the top microstrip coupled patches and the bottom modified nonuniformly short-circuited CPW resonator. Simulated results from the electromagnetic (EM) analysis software and measured results from a vector network analyzer (VNA) show a good agreement. A designed and fabricated prototype filter having a 3 dB cutoff frequency (fc) of 5.78 GHz has shown an ultrawide high-pass behavior, which exhibits the highest passband frequency exceeding 4.0fcunder the minimum insertion loss (IL) 0.75 dB. The printed circuit board (PCB) area of the filter is approximately0.062λg×0.093λg, whereλgis the guided wavelength atfc.

scholarly journals Phoamtonic designs yield sizeable 3D photonic band gaps

2019 ◽  
Vol 116 (47) ◽  
pp. 23480-23486 ◽  
Author(s):  
Michael A. Klatt ◽  
Paul J. Steinhardt ◽  
Salvatore Torquato
Keyword(s):  
Band Gap ◽  
Volume Fraction ◽  
Photonic Band Gap ◽  
Three Dimensional ◽  
Band Gaps ◽  
Photonic Band Gaps ◽  
Photonic Networks ◽  
Photonic Waveguides ◽  
High Degree ◽  
Photonic Band

We show that it is possible to construct foam-based heterostructures with complete photonic band gaps. Three-dimensional foams are promising candidates for the self-organization of large photonic networks with combinations of physical characteristics that may be useful for applications. The largest band gap found is based on 3D Weaire–Phelan foam, a structure that was originally introduced as a solution to the Kelvin problem of finding the 3D tessellation composed of equal-volume cells that has the least surface area. The photonic band gap has a maximal size of 16.9% (at a volume fraction of 21.6% for a dielectric contrast ε=13) and a high degree of isotropy, properties that are advantageous in designing photonic waveguides and circuits. We also present results for 2 other foam-based heterostructures based on Kelvin and C15 foams that have somewhat smaller but still significant band gaps.

Tunable properties of one-dimensional photonic crystals that incorporate a defect layer of a magnetized plasma

2017 ◽  
Vol 31 (31) ◽  
pp. 1750239 ◽  
Author(s):  
Arafa H. Aly ◽  
Hussein A. Elsayed ◽  
Ayman A. Ameen ◽  
S. H. Mohamed
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Plasma Layer ◽  
Photonic Band Gap ◽  
Defect Layer ◽  
Magnetized Plasma ◽  
Characteristic Matrix ◽  
Angle Of Incidence ◽  
One Dimensional ◽  
Photonic Band

In this paper, we theoretically investigate the transmittance characteristics of one-dimensional defective photonic crystal in microwave radiations based on the fundamentals of the characteristic matrix method. Here, the defect layer is magnetized plasma. The numerical results show the appearance of defect peaks inside the Photonic Band Gap. The external magnetic field has a significant effect on the permittivity of the defect layer. Therefore, the position and intensity of the defect peak are strongly affected by the external magnetic field. Moreover, we have investigated the different parameters on the defect peaks as the plasma density, the thickness of the plasma layer and the angle of incidence. Wherefore, the proposed structure could be the cornerstone for many applications in microwave regions such as narrowband filters.

Photonic Crystals at Near-Infrared and Optical Wavelengths

2001 ◽  
Vol 707 ◽  
Author(s):  
Alexander Moroz
Keyword(s):  
Near Infrared ◽  
Volume Fraction ◽  
Dielectric Material ◽  
Photonic Band Gap ◽  
Three Dimensions ◽  
Optical Wavelengths ◽  
Dielectric Spheres ◽  
Silver Spheres ◽  
Photonic Band ◽  
Complete Photonic Band Gap

ABSTRACTAs demonstrated for the example of a diamond and zinc blende structure of dielectric spheres, small inclusions of a low absorbing metal with the volume fraction can have a fm dramatic effect on a complete photonic band gap (CPBG) between the 2nd-3rd bands. For example, in the case of silica coated silver spheres, the CPBG opens for 1:1% and fm exceeds 5% for 2:5%. Consequently, any dielectric material can be used to fabricate fm a photonic crystal with a sizeable and robust CPBG in three dimensions. Absorption in the CPBG of 5% remains very small ( 2:6% for 750 nm). The structure enjoys almost perfect scaling, enabling one to scale the CPBG from microwaves down to ultraviolet wavelengths.

scholarly journals Computational investigation of liquid-solid slurry flow through an expansion in a rectangular duct

2014 ◽  
Vol 62 (3) ◽  
pp. 234-240 ◽  
Author(s):  
Gianandrea Vittorio Messa ◽  
Stefano Malavasi
Keyword(s):  
Volume Fraction ◽  
Particle Density ◽  
Fluid Model ◽  
Solid Volume Fraction ◽  
Solid Particles ◽  
Rectangular Duct ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Two Fluid Model ◽  
Two Fluid

Abstract The flow of a mixture of liquid and solid particles at medium and high volume fraction through an expansion in a rectangular duct is considered. In order to improve the modelling of the phenomenon with respect to a previous investigation (Messa and Malavasi, 2013), use is made of a two-fluid model specifically derived for dense flows that we developed and implemented in the PHOENICS code via user-defined subroutines. Due to the lack of experimental data, the two-fluid model was validated in the horizontal pipe case, reporting good agreement with measurements from different authors for fully-suspended flows. A 3D system is simulated in order to account for the effect of side walls. A wider range of the parameters characterizing the mixture (particle size, particle density, and delivered solid volume fraction) is considered. A parametric analysis is performed to investigate the role played by the key physical mechanisms on the development of the two-phase flow for different compositions of the mixture. The main focuses are the distribution of the particles in the system and the pressure recovery

Photonic Crystals at Near-Infrared and Optical Wavelengths

2001 ◽  
Vol 694 ◽  
Author(s):  
Alexander Moroz
Keyword(s):  
Near Infrared ◽  
Volume Fraction ◽  
Dielectric Material ◽  
Photonic Band Gap ◽  
Three Dimensions ◽  
Optical Wavelengths ◽  
Dielectric Spheres ◽  
Silver Spheres ◽  
Photonic Band ◽  
Complete Photonic Band Gap

AbstractAs demonstrated for the example of a diamond and zinc blende structure of dielectric spheres, small inclusions of a low absorbing metal with the volume fraction fm can have a dramatic effect on a complete photonic band gap (CPBG) between the 2nd-3rd bands. For example, in the case of silica coated silver spheres, the CPBG opens for fm ≍ 1.1% and exceeds 5% for fm ≍ 2.5%. Consequently, any dielectric material can be used to fabricate a photonic crystal with a sizeable and robust CPBG in three dimensions. Absorption in the CPBG of 5% remains very small (≤ 2.6% for λ ≥ 750 nm). The structure enjoys almost perfect scaling, enabling one to scale the CPBG from microwaves down to ultraviolet wavelengths.

scholarly journals Behaviour and Stability of the Two-Fluid Model for Fine-Scale Simulations of Bubbly Flow in Nuclear Reactors

2015 ◽  
Vol 13 (4) ◽  
pp. 449-459 ◽  
Author(s):  
Henrik Ström ◽  
Srdjan Sasic ◽  
Klas Jareteg ◽  
Christophe Demazière
Keyword(s):  
Volume Fraction ◽  
Nuclear Reactors ◽  
Fluid Model ◽  
Bubbly Flow ◽  
Domain Size ◽  
Fuel Assemblies ◽  
Two Fluid Model ◽  
Liquid Flows ◽  
Two Fluid ◽  
Meso Scale

Abstract In the present work, we formulate a simplistic two-fluid model for bubbly steam-water flow existing between fuel pins in nuclear fuel assemblies. Numerical simulations are performed in periodic 2D domains of varying sizes. The appearance of a non-uniform volume fraction field in the form of meso-scales is investigated and shown to be varying with the bubble loading and the domain size, as well as with the numerical algorithm employed. These findings highlight the difficulties involved in interpreting the occurrence of instabilities in two-fluid simulations of gas-liquid flows, where physical and unphysical instabilities are prone to be confounded. The results obtained in this work therefore contribute to a rigorous foundation in on-going efforts to derive a consistent meso-scale formulation of the traditional two-fluid model for multiphase flows in nuclear reactors.

Analysis of Powder Segregation in Powder Injection Molding

2011 ◽  
Vol 217-218 ◽  
pp. 1372-1379
Author(s):  
Yu Hui Wang ◽  
Xuan Hui Qu ◽  
Wang Feng Zhang ◽  
Yan Li
Keyword(s):  
Fluid Flow ◽  
Injection Molding ◽  
Volume Fraction ◽  
Fluid Model ◽  
Powder Injection Molding ◽  
Powder Injection ◽  
Exchange Term ◽  
Mixture Density ◽  
Two Fluid Model ◽  
Two Fluid

The powder injection molding (PIM) combines the thermoplastic and powder metallurgy technologies to manufacture intricate parts to nearly shape. The powder segregation is a special effect arising in PIM different from than the pure polymer injection. The two-fluid flow model is used to describe the flows of binder and powder so as to realize the prediction of powder segregation effect in PIM injection. To take into account binder–powder interaction, the mixture model of inter-phase exchange term is introduced in the two-fluid model. The two-fluid equations largely resemble those for single-fluid flow but are represented in terms of the mixture density and velocity. The volume fraction for each dispersed phase is solved from a phase continuity equation. As the key to calculate the phase exchange term, the drag coefficient is defined as a function of mixture viscosity. The effective viscosity of binder and powder are agreed with the additive principle. The volume fractions of binder and powder give directly the evolution of segregation during the injection course. Segregation during PIM injection was simulated by software CFX and results were compared with experimental data with good agreement. The basic reasons that caused segregation are identified as boundary effect, differences in density and viscosity of binder and powder. The segregation zones are well predicted. This showed that the two-fluid model is valid and efficient for the prediction of the segregation effects in PIM injection.

Simulation of Counter-Current Gas-Liquid Churn Flow

2013 ◽  
Author(s):  
Matej Tekavčič ◽  
Boštjan Končar ◽  
Ivo Kljenak
Keyword(s):  
Best Practice ◽  
Nuclear Reactor ◽  
Volume Fraction ◽  
Fluid Model ◽  
Porous Wall ◽  
Sensitivity Study ◽  
Eddy Viscosity Model ◽  
Simulation Results ◽  
Two Fluid Model ◽  
Counter Current

A transient simulation of air-water counter-current flow by the means of two-fluid model with interface sharpening is performed. The gas-liquid inhomogeneous model with both phases considered as incompressible is used. Turbulence is modelled for each phase separately using the two-equation eddy viscosity model. The numerical domain consists of an axisymmetric wedge with the porous wall inlet region representing a vertical pipe experimental test section. Evolution of volume fraction, velocities and pressure variations along the interface is presented. Simulation results are compared with the known experimental data (from the literature) for the wave frequency and velocity. The present simulation is also compared to a known numerical simulation found in literature that used volume of fluid method. Sensitivity study of several modelling parameters is performed to evaluate and discuss their impact on simulation results in an attempt to establish best practice guidelines for modelling of realistic counter-current flows, important in nuclear reactor systems.

Optical Applications of Macroporous Silicon

2000 ◽  
Vol 638 ◽  
Author(s):  
Volker Lehmann
Keyword(s):  
Photonic Band Gap ◽  
Optical Quality ◽  
Imaging Systems ◽  
Macroporous Silicon ◽  
Pass Filter ◽  
High Optical Quality ◽  
Optical Cavities ◽  
Optical Applications ◽  
Two Dimensional Photonic Crystal ◽  
Photonic Band

AbstractTwo promising optical applications of macroporous silicon are presented. Due to the high contrast in dielectric constant between the air filled pores and the silicon walls the porous structure exhibits a photonic band gap for infrared radiation perpendicular to the pore axis. By photolithograpic patterning waveguides and optical cavities can be realized in this two-dimensional photonic crystal. Along the pore axis a short-pass filter characteristic is observed for ultraviolet and visible light. Such macropore filters are of high optical quality and may replace conventional filters in imaging systems.

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