Light Scattering by a Subwavelength Plasmonic Array: Anisotropic Model

We calculate the light transmission by a subwavelength plasmonic array using the boundary element method for parallel cylinders with different cross-sections: circular or elliptic with axis ratio 4:1. We demonstrate that plasmonic resonance is sharper for the case of horizontal ellipses. This structure is susceptible to refractive index variations in the media since the high derivatives of reflection and transmission coefficients are near the angle of total internal reflection. To obtain an approximate analytical expression, we used the model of a metallic layer. We explore the “sandwich” structure with an anisotropic film between two dielectrics and demonstrate its quantitative agreement with numerical results.

DFT Calculations for the HONO Elimination Process of CL-20 Conformers

The HONO elimination process is regarded to be an important initial decomposition process of energetic nitramines. Four CL-20 conformers based on the ε-CL-20 were obtained by the optimization at the m062x/cc-pvtz level in this study, and the Transition State (TS) and Intrinsic Reaction Coordinate (IRC) calculations were carried out at the same level. In addition, the rate coefficients and activation energy of the HONO elimination process were evaluated using conventional transition state theory (TST) and canonical variational transition state theory (CVT) with Eckart and small-curvature tunneling (SCT) methods to correct the transmission coefficients for the quantum tunneling effect. The calculation results have shown that the HONO elimination process concerning the nitro groups located on six numbered rings is the hardest to happen, and it seems that the longer distance between nitro groups and the adjacent hydrogen atom would result in the higher barrier energy; the HONO elimination process is most likely to happen for the axial positioning of nitro groups located on five numbered rings and most unlikely to happen for the ones located on six numbered rings; CL-20 II and CL-20 IV conformers are the most unstable one and most stable one concerning the reaction difficulty of the HONO elimination process.

Tunable polarization comb based on the electromagnetically induced transparency with hybrid metal-graphene metamaterial

Noted a linear-to-circular polarization comb based on electromagnetically induced transparency (EIT) with hybrid metal-graphene metamaterial in terahertz (THz) spectroscopy. Due to the near field coupling between the bright mode of metal cut-wire (MCW) and multiple dark modes, the multi-peak EIT effect is exhibited under the x-polarized incidence supported by the three-level theory. With another orthogonal MCW etched on the back of the SiO2, the asymmetry responses in both polarized incidences (x- and y-polarized waves) further triggers the linear-to-circular polarization conversion (LTCPC). The values of four corresponding circular-polarized frequencies combined with transmission coefficients respectively are 0.90 THz with 0.45, 1.02 THz with 0.64, 1.15 THz with 0.60, 1.32 THz with 0.53, confirmed via relevant axial ratios and the electric field distributions. On the other hand, the drastic phase changes in transparent windows raise high group delays, among which the maximum value approaches 325 ps. Additionally, DC-voltage-driven graphene strips are doped at both ends of the back MCW to enhance the reconfigurability, superior tunable transmission behaviors illuminated by y-polarization with obvious changes at 0.90 THz and 1.02 THz can be achieved with the dynamic Fermi level fluctuating between 0.01 eV and 0.8 eV. Such an implementation creates a novel path to polarization modulators, signal transceivers, and information transmission devices.

Universalities of anomalous properties in electron transport through different Z-shaped phosphorene nanoribbon devices

Aiming at improving the flexibility of designing the phosphorene-based nanodevices, we propose three kinds of Z-shaped phosphorene nanoribbons (ZPNRs), which are composed of two metallic nanoribbon electrodes and one semiconducting/metallic nanoribbon central region (CR). Many anomalous properties including the unexpected current increasing under the low bias voltage, the negative differential conductance, and the transition of the transport mechanism are found to be universal in different ZPNRs. Also, we find the current can be significantly suppressed by increasing the CR length, while no complete suppression can be induced by the increase of the CR width, indicating that the CR length and width will make different influences on the ZPNR transport. Moreover, the energy spectrums of two electrodes, the molecular energy levels of the CR, the transmission coefficients, and the transmission eigenstates are further calculated so as to clearly expound the anomalous properties and their universalities. We believe this research can provide a meaningful guidance for developing the phosphorene-based electronic devices.

Computation of synthetic seismogram in real earth model by eigen function expansion

The method of eigen function expansion has been used in the present study to compute synthetic or theoretical seismogram in layered elastic half-space of real earth model. Simple dislocation source model has been considered. The transverse (SH) or radial and vertical (P-SV) components of displacement field have been computed as summed modes and compared by using both exact and numerical techniques. The methods used in the study, include exact evaluation by propagator matrix approach using Reflection-Transmission coefficients as well as numerical computations using Runge-Kutta method of order 4. The specialty of the present study is to evaluate approximate displacement field for the earth models with homogeneous and / or inhomogeneous layers. The normalization technique has been used in the study to control the overflow errors. The study has an advantage to get an idea of earth structure or source model by an inverse iterative technique.

ISPH Simulation of Solitary Waves Propagating Over a Bottom-Mounted Barrier With k–ε Turbulence Model

Solitary wave propagating over a bottom-mounted barrier is simulated using the Incompressible Smoothed Particle Hydrodynamics (ISPH) method in order to study the generation and transport of turbulence associated with flow separation around submerged structures. For an accurate capture of turbulence characteristics during the wave propagation, rather than employing the standard sub-particle scale (SPS) model, the k-ε turbulence model is coupled with the numerical scheme. The results of the numerical model are compared with experimental data, and good agreement is observed in terms of mean velocity, free surface elevation, vorticity fields and turbulent kinetic energy. The numerical model is then employed to investigate the effects of wave non-linearity and geometrical size of the submerged barrier on the flow separation; and calculate the reflection, dissipation and transmission coefficients to evaluate the importance of energy dissipation due to the generation of vortices. The results of this study show that the developed ISPH method with the k-ε turbulence closure model is capable of reproducing the velocity fields and the turbulence characteristics accurately, and thus can be used to perform predictions of comprehensive hydrodynamics of flow-structure interactions in the urban hydro-environment systems.

Spin-dependent transport through helical Aharonov-Bohm interferometer

We discuss spin-dependent transport via tunneling Aharonov-Bohm interferometer formed by helical edge states tunnel-coupled to helical leads. We focus on the experimentally relevant high-temperature case as compared to the level spacing and obtain the full 4×4 matrix of transmission coefficients in the presence of magnetic impurities. We show that spin conserving and spin-flip transmission coefficients of the setup can be effectively tuned by the magnetic flux. These features are attractive due to possible applications for spintronics, magnetic field detection, and quantum computing.

Estimation of S-parameters and dielectric permittivity of quartz ceramics samples in millimeter waveband

A modified Nicholson – Ross – Weir method was used to determine complex parameters and dielectric permittivity of ceramic materials in the range 78.33–118.1 GHz. The measuring equipment is a meter of complex reflection and transmission coefficients, a waveguide measuring canal with a special measuring cell, consisting of two irregular waveguides and a waveguide chamber between them, which provides insignificant influence of higher-order modes. The dependences of the amplitude and phase of the reflection and transmission coefficients on frequency were obtained experimentally for fluoroplastic and three ceramic samples in the frequency range 78.33–118.1 GHz. The obtained S-parameters are processed according to an algorithm that includes their averaging based on the Fourier transform in order to obtain the values of the dielectric permittivity. Fluoroplastic was used as a reference material with a known dielectric constant. The dielectric constant of fluoroplastic has a stable value of 2.1 in the above mentioned frequency range. The dielectric constant of sample No. 1 varies from 3.6 to 2.5 at the boundaries of the range, sample No. 2 – from 3.7 to 2.1, sample No. 3 – from 2.9 to 1.5. The experimental data are in satisfactory agreement with the literature data for other frequencies taking into account the limits set by the measurement uncertainty.