Multilayered Graphene structures have emerged as promising materials for designing novel optical devices due to their unique light-matter interactions. One of the intriguing phenomena observed in these structures is plasmonic resonance, which occurs in specific configurations known as Kretschmann and Otto geometries. In this paper, we investigate the behavior of a multilayered structure consisting of bilayer Graphene under incident light using reflection coefficient calculations and wave dispersion equation solutions. Our results demonstrate that the number of plasmonic resonance positions in the reflection coefficient can vary depending on the structural parameters. This is attributed to the positioning of the dispersion curves of the hybrid modes in relation to the light line of the prism. For certain structural values, the dispersion curves may not be in the leaky range and do not cause a change in the reflection. This phenomenon opens up exciting possibilities for highly tunable optical device design. The findings of this study are not only relevant to the investigated configurations but also extend to the design of other optical devices such as waveguides, antennas, and multiplexers that utilize multilayered structures. Our results provide valuable insights for device designers, enabling them to precisely engineer multilayered structures by considering the importance and desirability of confined or leaky surface plasmon modes.

Since Graphene discovery, designing and implementation of electronic circuits have been developed in the THz and optical frequencies to achieve ultrafast responses. Thus, electromagnetic shielding due to its protection effects against disturbances caused by adjacent elements has emerged as a vital issue in circuit designing. In this paper, two types of electromagnetic shields are proposed in the THz regime. Regarding the adjustability of Graphene’ s conductivity, one can easily tune the frequency response in order to adapt it with the frequency range in which their circuit works. In order to accelerate the computation of shield efficiency factor, firstly an equivalent circuit model is proposed as a closed-form expression, and then shield efficiency can be achieved using transmission line model. Comparisons indicate that the results derived from the proposed method are in high accordance with those of CST-MWS commercial software. Finally the effects of the number of layers, the thickness of SiO2 layers, the width of Graphene ribbons, the gap between the two individual cells, Fermi energies, and oblique incident on the shielding effectiveness of the proposed structure are discussed in details for interesting readers.

Density functional theory (DFT) and thermal DFT (thDFT) calculations were used to evaluate the energy band structure, bandgap, and the total energy of various Graphene quantum dots (GQDs). The DFT calculations were performed using local density approximation for the exchange-correlation functional and norm-conserving pseudopotentials. We consider the triangular and hexagonal GQDs with zigzag and armchair edges and 1-3 nm dimensions with many hundred atoms. The simulation results show that all of these GQDs are direct bandgap semiconductors with a flat band structure, and they are suitable for electronics and optoelectronics applications. Analysis of GQDs in which the A and B sublattice symmetries were broken showed degenerate zero-energy shells. Using the thDFT calculations carried out at temperatures up to 1400 K, we evaluated the temperature dependence of the GQDs bandgaps and total energies via entropy-term and electron’ s kinetic energy. The obtained results indicate that the ground-state DFT calculations are valid for determining the electronic properties of GQDs up to room temperature. Moreover, we tune semi-empirical parameters of the tight-binding model by the DFT results in small GQDs to reduce the computational cost of electronic structure calculations for large GQDs, which contained up to thousands of atoms.

We have investigated the optical properties of the double-periodic structure containing Graphene-based hyperbolic metamaterial using the transfer matrix method and the effective medium theory at the Terahertz frequency region. Our findings reveal that this structure may have multiple band gaps in hyperbolic and elliptical frequency regions. Moreover, it shows that the transmission and absorption for TM polarization depend on both Graphene chemical potential and optical axis orientation of the hyperbolic metamaterial layers. However, in the TE polarization case, these optical properties only depend on Graphene chemical potential.

A study on buckling analysis of Marine sandwich panels for interior partition walls with multilayer Graphene nanoplatelet (GPL)/polymer composite facesheets is presented in this paper. Three different shapes of square, honeycomb, and re-entrant cellular shape with negative poison ratio are considered for the core layer. It is assumed that facesheets be composed of a polymer matrix reinforced by Graphene nanoplatelet (GPL). Halpin-Tsai's micromechanical approach is used to determine the effective Young’s modulus of the top and bottom layers and the rule of mixture for effective Poisson’s ratio and mass density. The wall sandwich plate is modeled based on a new fifth-order shear deformation theory. Hamilton principle is employed to obtain the governing differential equations of motions of plates. The accuracy of the proposed formula and results are verified and proven accurate by the high agreement with the available results in the literature. Based on our results, we indicated the effect of cell configurations of the cellular core on the critical buckling load of marine interior wall sandwich plates. Moreover, the effect of thickness, aspect ratios, Graphene nanoplatelet weight fraction, and geometrical parameters on the critical buckling load by the use of Galerkin’s method is illustrated. The findings of this research may be beneficial in creating more efficient engineering applications, especially in the marine and ship industries.

This work is based on the density function theory (DFT) and time-dependent density function theory methods (TD-DFT) to investigate the density of states (DOS), FT-IR spectra, electro-optical and thermal, properties of Ga-doped Graphene molecule (GM). The Graphene molecule structure is found to be exhibiting semiconductor activity in a pure state with a wide band gap of 3.92301 eV. The defect of Graphene molecule with Ga has been demonstrated to depress the band gap values of GM structure significantly as a result of calculations. The electronic characteristics of Graphene in its ground state and low-lying excited states may change based on the structural characteristics of Ga impurity in the GM structure. The results indicate that the electrical characteristics of GM are influenced by the geometrical distribution of Ga impurities in the GM structure. The consequences of Ga impurity are discussed for both GM ground and excited electronic states of GM are explored.