scholarly journals Coupled-Cavity Structures in Photonic Crystals

2002 ◽  
Vol 722 ◽  
Author(s):  
Mehmet Bayindir ◽  
E. Ozbay
Keyword(s):  
Photonic Crystals ◽  
Electromagnetic Waves ◽  
Tight Binding ◽  
Solid State Physics ◽  
Field Patterns ◽  
Cavity Modes ◽  
Fdtd Simulations ◽  
Difference Time ◽  
Coupled Cavity ◽  
Good Agreement

AbstractWe investigate the localized coupled-cavity modes in two-dimensional dielectric photonic crystals. The transmission, phase, and delay time characteristics of the various coupled-cavity structures are measured and calculated. We observed waveguiding through the coupled cavities, splitting of electromagnetic waves in waveguide ports, and switching effect in such structures. The corresponding field patterns and the transmission spectra are obtained from the finite-difference-time-domain (FDTD) simulations. We also develop a theory based on the classical wave analog of the tight-binding (TB) approximation in solid state physics. Experimental results are in good agreement with the FDTD simulations and predictions of the TB approximation.

Spectral Control of Thermal Radiation by Metallic Surface Relief Gratings

2009 ◽  
Vol 1162 ◽  
Author(s):  
Hitoshi Sai ◽  
Yoshiaki Kanamori ◽  
Kengo Watanabe ◽  
Hiroo Yugami
Keyword(s):  
Surface Relief ◽  
Spectral Emissivity ◽  
Metallic Surface ◽  
Time Domain Simulation ◽  
Peak Structure ◽  
Cavity Modes ◽  
Spectral Control ◽  
Surface Relief Gratings ◽  
Difference Time ◽  
Good Agreement

AbstractThe microcavity effect of two-dimensional W surface-relief gratings has been investigated by means of the finite-difference time-domain simulation. The peak structure of the spectral emissivity of W gratings with a number of microcavities is in good agreement with the spectral features of a single microcavity. This result shows that the emissivity enhancement by W gratings with microcavities is mainly attributable to the microcavity effect that arises from each microcavity. It is that the spectral emissivity can be controlled by a combination of several microcavities with different parameters, and that not only a rectangular but a cylindrical microcavity also shows the microcavity effect according to its cavity modes.

The working standard of the unit of power of electromagnetic waves in the frequency range from 37,5 to 220 GHz

2020 ◽  
pp. 53-58
Author(s):  
A. V. Koudelny ◽  
I. M. Malay ◽  
V. A. Perepelkin ◽  
I. P. Chirkov
Keyword(s):  
Microwave Power ◽  
Electromagnetic Waves ◽  
Primary Standard ◽  
The State ◽  
Frequency Range ◽  
Working Standard ◽  
Extended Frequency Range ◽  
Effective Efficiency ◽  
Extended Frequency ◽  
Good Agreement

The possibility of using bolometric converters of microwave power from the State primary standard of the unit of power of electromagnetic waves in waveguide and coaxial paths GET 167-2017, which has a frequency range from 37,5 to 78,33 GHz, in an extended frequency range up to 220 GHz, is shown. Studies of semiconductor bolometric converters of microwave power in an extended frequency range have confirmed good agreement and smooth frequency characteristics of the effective efficiency factor of the converters. Based on the research results, the State working standard of the unit of power of electromagnetic waves of 0,1–10 mW in the frequency range from 37,5 to 220 GHz 3.1.ZZT.0288.2018 was approved. The technical characteristics of the working standard of the unit of power of electromagnetic oscillations in an extended frequency range from 37,5 to 220 GHz are given.

scholarly journals Designing the Hotspots Distribution by Anisotropic Growth

Molecules ◽  
2021 ◽  
Vol 26 (1) ◽  
pp. 187
Author(s):  
Tianshun Li ◽  
Renxian Gao ◽  
Xiaolong Zhang ◽  
Yongjun Zhang
Keyword(s):  
Au Nanoparticles ◽  
Fdtd Method ◽  
Polarization Dependence ◽  
Noble Metal Nanoparticles ◽  
Oblique Angle Deposition ◽  
Matlab Simulation ◽  
Different Shapes ◽  
Plasma Enhancement ◽  
Difference Time ◽  
Good Agreement

Changing the morphology of noble metal nanoparticles and polarization dependence of nanoparticles with different morphologies is an important part of further research on surface plasma enhancement. Therefore, we used the method based on Matlab simulation to provide a simple and effective method for preparing the morphologies of Au nanoparticles with different morphologies, and prepared the structure of Au nanoparticles with good uniformity and different morphologies by oblique angle deposition (OAD) technology. The change of the surface morphology of nanoparticles from spherical to square to diamond can be effectively controlled by changing the deposition angle. The finite difference time domain (FDTD) method was used to simulate the electromagnetic fields of Au nanoparticles with different morphologies to explore the polarization dependence of nanoparticles with different shapes, which was in good agreement with Raman spectrum.

Effects of band non-parabolicity on cavity modes in photonic crystals

2013 ◽  
Vol 113 (6) ◽  
pp. 063105
Author(s):  
N.-Y. Lue ◽  
Y.-S. Chen ◽  
H.-S. Wei ◽  
G. Y. Wu
Keyword(s):  
Photonic Crystals ◽  
Cavity Modes

Metallic condensation of Wannier-Mott impurity states in lithium-hexamethylphosphoramide glasses

1977 ◽  
Vol 55 (11) ◽  
pp. 2258-2263 ◽  
Author(s):  
Peter P. Edwards ◽  
Ron Catterall
Keyword(s):  
Tight Binding ◽  
Mott Transition ◽  
Electron Interaction ◽  
Metallic State ◽  
Binding Model ◽  
Impurity States ◽  
Coulombic Repulsion ◽  
Variational Form ◽  
Frozen Solutions ◽  
Good Agreement

A metal to non-metal (MNM) transition observed in frozen solutions of lithium in hexamethylphosphoramide (HMPA) was tentatively interpreted as a Mott transition in which localized Wannier-type impurity states were the source of electrons in the metallic state. In this paper this assertion is examined in greater detail by calculating critical densities (nc) on the basis of a scaled (variational) form of Mott's original criterion for the onset of localization in a dielectrically screened Coulomb potential, and also on the basis of the Hubbard tight-binding model. Mott's model for the transition is based upon the screening properties of a freely propagating gas of metallic electrons. In the Hubbard regime, however, the phenomenon is viewed from the tight-binding limit; the transition from localized to delocalized states occurs when the bandwidth (Δ) of a regular lattice of isolated centres exceeds the value of the intra-atomic Coulombic repulsion integral (U) associated with electron correlation.Both electron-gas (Mott) and tight-binding (Hubbard) approaches give calculated critical densities (5.6 × 1018, 3.2 × 1018 cm−3, respectively) in good agreement with the experimental value (∼3 × 1018 cm−3). These results therefore support the earlier suggestion that the MNM transition in frozen lithium-HMPA solutions is a Mott-transition associated with electron-interaction effects.

Focusing Technique for Holographic Subsurface Radar Based on Image Entropy

2021 ◽  
Vol 36 (4) ◽  
pp. 373-378
Author(s):  
Haewon Jung ◽  
Dal-Jae Yun ◽  
Hoon Kang
Keyword(s):  
Numerical Simulation ◽  
Time Domain ◽  
Finite Difference Time Domain ◽  
Software Package ◽  
Reconstruction Algorithm ◽  
Simulation Software ◽  
Material Information ◽  
Difference Time ◽  
Actual Depth ◽  
Good Agreement

An image focusing method for holographic subsurface radar (HSR) is proposed herein. HSR is increasingly being utilized to survey objects buried at shallow depths and the acquired signals are converted into an image by a reconstruction algorithm. However, that algorithm requires actual depth and material information or depends on human decisions. In this paper, an entropy-based image focusing technique is proposed and validated by numerical simulation software package based on finite-difference time-domain method and experiment. The resulting images show good agreement with the actual positions and shapes of the targets.

Transmissive 2-bit anisotropic coding metasurface

2022 ◽  
Author(s):  
Pengtao Lai ◽  
Zenglin Li ◽  
Wei Wang ◽  
Jia Qu ◽  
Liang Wei Wu ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Electromagnetic Wave ◽  
Circular Polarization ◽  
Orbital Angular Momentum ◽  
Electromagnetic Waves ◽  
Beam Splitter ◽  
Far Field ◽  
Polarization Conversion ◽  
Field Patterns ◽  
Phase Profile

Abstract Coding metasurfaces have attracted tremendous interests due to unique capabilities of manipulating electromagnetic wave. However, archiving transmissive coding metasurface is still challenging. Here we propose a transmissive anisotropic coding metasurface that enables the independent control of two orthogonal polarizations. The polarization beam splitter and the OAM generator have been studied as typical applications of anisotropic 2-bit coding metasurface. The simulated far field patterns illustrate that the x and y polarized electromagnetic waves are deflected into two different directions, respectively. The anisotropic coding metasurface has been experimentally verified to realize an orbital angular momentum (OAM) beam with l = 2 of right-handed polarized wave, resulting from both contributions from linear-to-circular polarization conversion and the phase profile modulation. This work is beneficial to enrich the polarization manipulation field and develop transmissive coding metasurfaces.

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