Modern Physics Letters B

A metal-dielectric-metal (MDM) sandwich metamaterial perfect absorber (MPA) with magnetic nickel metal has been designed. An optimal absorption of 99.28% at 404 MHz is achieved for MPA with thickness of 5.54 mm. Resonant absorption is demonstrated to be main mechanism according to analyses on surface current distributions and electromagnetic field distributions. Furthermore, the electromagnetic energy is mainly dissipated in magnetic metal with magnetic loss proportion of 55.43% by comparatively analyzing the wave-absorbing performance of using magnetic metal, non-magnetic metal and perfect electric conductor (PEC) as metallic layers. These results would provide a guidance for the design of quasi-microwave absorbing/shielding materials.

Electronic band structures of ${\mathrm{\text{InP}}}_{(1-x-y)}{\mathrm{\text{Bi}}}_x{\mathrm{\text{N}}}_y$ have been theoretically studied by using Conduction Band Anticrossing (CBAC) model and Valence Band Anticrossing model (VBAC) in conjugation with $k\cdot p$ method. This mathematical model’s manifestation is a 16 band Hamiltonian matrix. Our results reveal that the addition of Bi and N to InP causes substantial reduction of band gap, and the conduction band offset is greater than valence band offset. It can provide better electronic confinement and improve the temperature-insensitive characteristics for optoelectronic devices. Material compositions and band gap under various strain conditions have also been added in our calculation. By adjusting the concentration of Bi and N, we obtained a strong control of conduction band edge and valence band edge, which increases the flexibility of design InPBiN/InP structures.

In this paper, we construct exact families of traveling wave (periodic wave, solitary wave, shock wave, singular-wave, singular-periodic wave, and singular-solitary wave) solutions of a well-known system of nonlinear PDEs, the Wu–Zhang system, which describes (1+1)-dimensional dispersive long waves. This system is solved by using the generalized $(G^{\prime }/G)$ expansion method, where G satisfies the Jacobi elliptic equation of fourth order. Meanwhile, the mechanical features of some families are explained through three-dimensional figures.

This study investigated the influences of Cu, high temperature-treated Cu (H-Cu) and graphene-coated Cu (G-Cu) substrates on interfacial reaction, microstructure and hardness of Sn-3.0g-0.5Cu (SAC305) solder alloy. Intermetallic compound (IMC) layer evolution and mechanical property of Sn-3.0g-0.5Cu-0.3Ni (SAC305-0.3Ni) solder joints were also studied under different aging duration. A continuous scallop-like IMC layer was observed at SAC305/Cu, SAC305/H-Cu, SAC305/G-Cu interfaces during reflow and isothermal aging. After adding Ni in the SAC305-0.3Ni solder alloy, the roughness of IMC layer on Cu, H-Cu substrates increased. In contrast, the addition of Ni had a limited impact on the roughness of IMC layer on G-Cu substrates. The total thickness of IMC layer grew as aging time increases, proportionated to the square root of aging duration. The addition of Ni in the solder alloy promoted the growth of IMC layer on Cu and H-Cu substrates, but it was restrained on G-Cu substrate. The amount of the IMC phases in SAC305 and SAC305-0.3Ni solder bulks on the three substrates increased significantly as aging time prolonged. Thus, the hardness of SAC305 and SAC305-0.3Ni solder bulks on the three substrates rose. The addition of Ni in the solder bulks on the three substrates sharply enhanced the formation of $\beta$-Sn phases and increased the quantity of the IMCs. Consequently, the hardness of SAC305-0.3Ni solder bulks was higher than that of SAC305 solder bulk on the three substrates under same aging condition. In addition, the graphene-coated layer on G-Cu substrate could improve the hardness of SAC305 and SAC305-0.3Ni solder bulks.

A new generalized exponential rational function method (GERFM) is used to acquire some new optical solitons of Radhakrishnan–Kundu–Lakshmanan (RKL) equation with Kerr nonlinearity. This equation is used to model propagation of solitons through an optical fiber. The well-known exponential rational function method is also a special case of the GERFM. The results reveal that the mentioned method is efficient and simple for solving different nonlinear partial differential equations.

Quantum wires occupy a unique status among the semiconducting nanostructures with reduced dimensionality, no other system seems to have engaged researchers with as many appealing features to pursue. This paper aims at a core issue related with the magnetoplasmon excitations in the quantum wires characterized by the confining harmonic potential and subjected to a longitudinal electric field and a perpendicular magnetic field in the symmetric gauge. Despite the substantive complexity, we obtain the exact analytical expressions for the eigenfunction and eigenenergy, using the scheme of ladder operators, which fundamentally characterize the quantal system. Crucial to this inquiry is an intersubband collective excitation that evolves into a magnetoroton — above a threshold value of magnetic field — which observes a negative group velocity between the maxon and the roton. The evidence of negative group velocity implies anomalous dispersion in a gain medium with the population inversion that forms the basis for the lasing action of lasers. Thus, the technological pathway that unfolds is the route to devices exploiting the magnetoroton features for designing the novel optical amplifiers at nanoscale and hence paving the way to a new generation of lasers.

Computed Tomography (CT) is considered as a significant imaging tool for clinical diagnoses. Due to low-dose radiation in CT, the projection data is highly affected by Gaussian noise which may lead to blurred images, staircase effect, loss of basic fine structure and detailed information. Therefore, there is a demand for an approach that can eliminate noise and can provide high-quality images. To achieve this objective, this paper presents a new statistical image reconstruction method by proposing a suitable regularization approach. The proposed regularization is a hybrid approach of Complex Diffusion and Shock filter as a prior term. To handle the problem of prominent Gaussian noise as well as ill-posedness, the proposed hybrid regularization is further combined with the standard Maximum Likelihood Expectation Maximization (MLEM) reconstruction algorithm in an iterative manner and has been referred to as the proposed CT-Reconstruction (CT-R) algorithm here after. Besides, considering the large sizes of image data sets for medical imaging, distributed storage for images have been employed on Hadoop Distributed File System (HDFS) and the proposed MLEM algorithms have been deployed for improved performance.The proposed method has been evaluated on both the simulated and real test phantoms. The final results are compared with the other standard methods and it is observed that the proposed method has many desirable properties such as better noise robustness, less computational cost and enhanced denoising effect.

A potential scheme to produce the water window single attosecond pulses (SAPs) from the multi-cycle mid-infrared (MIR) laser field has been investigated with the help of the chirp gating modulation. It is found that with the introduction of the laser chirp (i.e. up-chirp or down-chirp modulation), the extension of the harmonic cutoff can be achieved and the single harmonic radiation peak (HRP) can be selected during the harmonic emission process. Moreover, the chirp gating modulation on the high-order harmonic generation (HHG) is sensitive to the few-cycle pulse duration, but it is not very sensitive to the multi-cycle pulse duration. Moreover, a larger extension of the harmonic cutoff covering the whole water window region can be found with the help of the multi-cycle down-chirp modulation. Further, by properly choosing the coherent superposition of the ground state and the high Rydberg state as the initial state, the efficiency of HHG can be enhanced by 5 orders of magnitude. Finally, a series of high-intensity sub-40as pulses covering the water window region can be obtained.

The paper presents the ring formation during the course of filamentation in laser and weak inhomogeneous plasma interaction. Due to the combined influence of off-axial component and plasma density ripple, normal single ring changed into abnormal splitted ring during the course of filamentation. With increase in off-axial component and plasma density ripple, the abnormal splitted ring became stronger.

In this paper, is the hydrodynamics of three in-line square cylinders in a uniform flow, where the gap between two neighboring square cylinders is equivalent is under investigation. The fluid dynamics around those multiple bluff bodies, including time-mean drag coefficients, time-mean lift coefficients and Strouhal numbers, are considered at the Reynolds number $Re\approx 100$. Through numerically solving the nonlinear hydrodynamic problem, we show that the drag force acting on the first square cylinder is always larger than that acting on the remaining two square cylinders. From the perspective of wake structures, with keeping the increase of the gap between two neighboring square cylinders, the wake structures become much more complicated, including attachment of shear layer, interaction between shear layer and vortex, interaction between vortex and vortex, etc. Moreover, the Strouhal number of three square cylinders are approximately equaled when the dimensionless gap between two neighboring square cylinders is less than 2.

By using the Hirota bilinear method, new interaction solutions and the periodic lump wave solutions for the Jimbo–Miwa equation are successfully solved via symbolic computation with Maple. These new solutions greatly enrich the existing literature on the Jimbo–Miwa equation. Via the three-dimensional images and density images, the physical characteristics of the interactions and the periodic lump wave are well observed. These physical features of the waves obtained in this paper will be widely used in the fields of electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics.

Within the framework of the dielectric continuum approach and modified random-element-isodisplacement model, the optical vibration mode in a spherical core-shell quantum dot (CSQD) consisting of ternary mixed crystals (TMCs) are investigated. The dispersion relation and electron–phonon interaction Hamiltonian are derived. As a typical case, the numerical results for $\mathrm{\text{ZnS}}/{\mathrm{\text{Zn}}}_x{\mathrm{\text{Cd}}}_{1-x}\mathrm{\text{S}}$ and $\mathrm{\text{GaAs}}/{\mathrm{\text{Al}}}_x{\mathrm{\text{Ga}}}_{1-x}\mathrm{\text{As}}$ CSQDs are obtained and discussed. Taking the one- and two-mode behaviors of TMCs into account, the effects of TMCs on interface/surface optical (IO/SO) phonon show that there are 3 and 5 branches of IO/SO phonon modes in $\mathrm{\text{ZnS}}/{\mathrm{\text{Zn}}}_x{\mathrm{\text{Cd}}}_{1-x}\mathrm{\text{S}}$ and $\mathrm{\text{GaAs}}/{\mathrm{\text{Al}}}_x{\mathrm{\text{Ga}}}_{1-x}\mathrm{\text{As}}$ CSQDs for a given component of TMC, respectively. It is also found that the IO/SO phonon frequencies and electron–phonon interactions are strongly dependent on the component of TMCs and the size of CSQDs. We hope this work would be useful for the study of the phonon-related photoelectric properties in CSQDs consisting of TMCs.

Plasmonic planar lens consisting of circular nanohole etched on the gold film have been investigated, the proposed plamonic lens was immersed in a high index medium to improve the focusing efficiency. The focal length and the full-width half-maximum beams width of the focal point were calculated in detail. The focal length calculated by FDTD simulation agrees well with Rayleigh–Sommerfeld integral. Moreover, the proposed lens structure is polarization-independent since circularly symmetric. The easy fabricate structure and excellent focusing performance of this plasmonic lens will open new avenues for optical storage and optical integration.

Recently, Wang et al. [Wang et al., Quantum Inf. Process. 16 (2017) 221] developed generalized teleportation schemes based on different quantum walks structures. In their paper, an interesting open question is whether there are other graphs suitable for teleportation. Here, we extend the results of quantum teleportation of an unknown qubit state by means of discrete-time quantum walks and propose two kinds of schemes for quantum teleportation by means of discrete-time quantum walks on N-lines and N-cycles, respectively. Likewise, prior quantum entanglement is unnecessary for teleportation and quantum entanglement is generated by means of quantum walks. This further opens wider applications of quantum walks in quantum communication protocols.