Dispersion characteristics of two types of two-dimension dielectric plasma photonic crystal are studied based on modified plane wave method. Firstly, the eigenvalue equations of TM mode of type-1 and type-2 structures are derived respectively; their dispersion curves are confirmed by the software simulation. Secondly, the influences of normalized plasma frequency, filling factor and relative dielectric constant on photonic band gap, and relative photonic band gap width are analyzed respectively, and some corresponding physical explanations are also given. These results would provide theoretical instructions for designing new photonic crystal devices using plasma- dielectric structure.

https://www.jpier.org/PIER/pier91/20.09022605.pdf

Modified Plane Wave Method Analysis of Dielectric Plasma Photonic Crystal

In this paper, we study tunable metamaterial structures whose unit cell has triangular split ring resonator and wire strip for S- and C-microwave bands. Three types of new metamaterials, concentric and non-concentric conflgurations, are designed, and their electromagnetic response is investigated. Constitutive and S parameters are computed using retrieval algorithm to demonstrate the properties of the proposed new metamaterial designs. In addition, the electric fleld distribution on the metallic parts of the structure is illustrated for one design of the each sample. It is shown that the studied new metamaterials exhibit double negative properties in the frequency region of interest. The main advantage of this study based on the proposed structures is having the tunability in terms of the substrate thickness and the possibility of pronounced loss reduction.

/pdf/tunable-metamaterial-design-composed-of-triangular-split-1pn1cq5azh.pdf

Tunable metamaterial design composed of triangular split ring resonator and wire strip for s- and c- microwave bands

The article provides a discussion on the studies comprising active experiments conducted on selected structural components, the purpose of which was to analyse the impact of properties of the material used on the dynamic state form. The vibration excitation was achieved by applying a force impulse of a specific value. The studies were conducted on excitations acting perpendicularly to the surface of the component being examined in strictly established geometric arrangements. Consequently, signals were obtained to be subsequently applied for the sake of analysis of the impact of material properties on the manner of the vibration energy propagation in the machine components examined. The signal processing method used was based on application of a time and frequency transformation which enables obtaining the information the signals carry in two domains simultaneously, namely those of time and frequency. The results provided and discussed evidence the applicability of the method described in the analysis of the material impact on dynamic properties of the given structural component.

Method of Assessing the Impact of Material Properties on the Propagation of Vibrations Excited with a Single Force Impulse

Calculation of the emission power distribution of microstructured OLEDs using the reciprocity theorem

Terahertz metamaterials (THz MMs) have been proven to be good candidates for chemical, biological, temperature, strain, and position sensing. However, currently developed thin-metal-film-based split ring resonator (SRR) MMs have relatively low quality factor (Q-factors), leading to a poor sensitivity, which is one of the obstacles for development of sensors. In order to enhance the Q-factor, novel THz MMs, nanopillar-based MMs, are designed, fabricated, and characterized. The nanopillar-based MMs excite the inductive-capacitive resonance via desplacement currents, showing a significantly enhanced Q-factor around 450, which is about 30 times higher than typical thin-metal-film-based MMs. Nanopillar-based MMs also show 17 times larger frequency shift compared to the metal-film-based MMs when the permittivity of the ambient dielectric properties of the MMs changes. Due to high Q-factor and large frequency shift, the nanopillar-based THz MMs utilizing displacement current have great potential for highly sensitive chemical and biomaterial detection as well as frequency-agile THz devices.

Displacement Current Mediated Resonances in Terahertz Metamaterials

Light extraction efficiency of light-emitting diodes (LEDs) based on various photonic crystal (PhC) structures is investigated in this study. By using the plane wave method and the finite element method, the influence of several factors on the enhancement of light extraction is discussed, including lattice type, the density of states from a photonic band diagram, the ratio of cylinder radius and lattice constant, and the thickness of a PHC pattern. Some rules are given for the practical implementation of an optimized PhC-based LED with higher light extraction efficiency. In the simulation results, the maximum enhancement of the extraction efficiency could be by a factor of approximately 2.8 for the optimized Archimedean tiling pattern in the LED device emitting at the center wavelength of 530 nm. However, with the use of optimized PhC structures, the square and triangular lattices reveal enhancements of ∼ 1.7 and ∼ 1.5, respectively. The extraction efficiency of the Archimedean PhC LED is much greater than that of the regular lattice PhC LED.

/pdf/design-and-modeling-for-enhancement-of-light-extraction-in-3dl7nodh3a.pdf

Design and modeling for enhancement of light extraction in light-emitting diodes with Archimedean lattice photonic crystals

The magnetic resonance of various split ring resonators (SRRs) is numerically investigated to analyze the dependence of the resonance frequency on their parameter designs. The behavior of the magnetic resonance frequency in the configuration of the 2-cut singlering SRR (2C-SRR) shows a larger shift in relation to the changes of the SRR size scaling, split width and substrate permittivity. A new magnetic particle formed by the 2C-SRR structure incorporating nematic liquid crystals (LCs) into the multilayered substrate is proposed for the realization of a tunable magnetic metamaterial. When using such inclusions, the tuning range of the magnetic resonance conditions could be as wide as ∼ 1.1GHz via changing the orientation of LC molecules by 90◦.

Comparative analysis of split-ring resonators for tunable negative permeability metamaterials based on anisotropic dielectric substrates

High resolution finite volume scheme for the quantum hydrodynamic equations

In this study, the influence on wave propagation of periodic structures having defects is investigated. Defects are used in periodic structures to study the unique characteristics of wave propagation in a periodic system. A structural rod model is developed to study the problems of one-dimensional periodic structures with defects. A finite element model and a transfer matrix method are developed to study these problems to predict the performance of the system; moreover, a shape memory alloy (SMA) is used to control the characteristics of the system. The behaviors of the periodic structure are evaluated at different length ratios and material properties of the defects. The effects of the SMA when applied at various temperatures are also discussed. The location and width of stop bands can be changed with different configurations of the additional defects.

/pdf/control-of-wave-propagation-in-periodic-structures-having-5d7sikqmky.pdf

Control of Wave Propagation in Periodic Structures Having Defects

The dynamic stability of sandwich annular plate with an electrorheological (ER) fluid core and constraining layer are studied. The annular plate is covered an electrorheological fluid core layer and a constraining layer to improve the stability of the system. The discrete layer annular finite element and the harmonic balance method are adopted to calculate the boundary of instability regions for the sandwich annular plate system. Besides, the rheological property of an electrorheological material, such as viscosity, plasticity, and elasticity can be changed when applying an electric field. When the electric field is applied on the sandwich structure, the damping of the sandwich system is more effective. Thus, variations of the instability regions for the sandwich annular plate with different applying electric fields and thickness of ER layer are presented and discussed in this study. The ER fluid core is found to have a significant effect on the location of the boundaries of the instability regions.

Jia-Yi Yeh

Papers

Design and modeling for enhancement of light extraction in light-emitting diodes with Archimedean lattice photonic crystals

Comparative analysis of split-ring resonators for tunable negative permeability metamaterials based on anisotropic dielectric substrates

High resolution finite volume scheme for the quantum hydrodynamic equations

Control of Wave Propagation in Periodic Structures Having Defects

Dynamic Stability Analysis of Sandwich Annular Plate with ER Core Treatment