فهرست مطالب مهران شاه منصوری

In this paper, a unique symmetric graphene-based plasmonic nano-waveguide is proposed to guiding electromagnetic waves in the mid-infrared spectrum. The geometric structure of the waveguide consists of two symmetrical cylinders arranged around a rectangular substrate with a high refractive index. The lateral surfaces of both cylinders are covered with a graphene monolayer, and the cylinders and rectangular substrate are placed in a low refractive index environment. Here, the modal model properties of surface plasmon polaritons are investigated using the finite element method. The dependence of the propagation properties of the modes on the frequency of the incident wave, the graphene Fermi energy and the dimensions of the geometric structure of the waveguide has been calculated in detail. Due to the unique structure of the designed waveguide, the propagation length of the modes is approximately 4600 nm , the normalized mode area is ~〖10〗^(-6) and the figure of merit is nearly 500. According to the simulation results, this structure has a strong confinement the light subwavelength and high performance in the mid-infrared region for use in practical applications in photonic integrated circuits.

In this paper, a high-performance graphene dielectric plasmonic waveguide in the far infrared spectrum is proposed, which is one of the components of integrated photonic and optoelectronic circuits with various applications, including communications, military, medical, etc. The proposed waveguide geometric structure is composed of a rectangular cube layer with a semi-cylindrical ridge underneath (with a high refractive index material), rectangular cube substrate with a semi-cylindrical depression (with a low refractive index material), a sheet of graphene and the substrate of material with low refractive index, that the layers and sublayers are stacked on top of each other, respectively. Here, the surface plasmon polaritons (SPPs) modes are stimulated at the interface of graphene and dielectric. The propagation properties of SPPs modes have been investigated using the finite element method (FEM). The simulation results show that via modifying the geometrical parameters of the structure and tuning the chemical potential of the proposed graphene waveguide, a small normalized mode area ~〖10〗^(-4) and the propagation length ~〖10〗^3 μm are achieved. Therefore, it is recommended that the proposed waveguide can be used as a component of photonic devices due to relatively long propagation length and the strong confinement of light.

Propagation of electrostatic waves in a quantum semiconductor plasma has been investigated by a quantum hydrodynamic model in the presence of an external magnetic field. The influence of quantum effects such as Fermi pressure, Bohm potential and exchange potential on the propagation properties of electrostatic waves has been investigated. We found that the quantum effects and external magnetic field significantly modify the electrostatic wave frequency.

Nonlinear Dust lattice modes are studied in a hexagonal two-dimensional dusty plasma lattice, in presence of charge gradient of dust particles. In this lattice, such gradients affect nonlinear behavior of dust lattice waves. The amplitude modulation of off-plane transverse dust lattice wave packets is investigated considering the anisotropy of interactions, caused by the height-dependent charge variations. A nonlinear Schrodinger equation described time evolution of modulated off-plane transverse dust lattice wave packet. Calculations show that the charge gradient changes the stability condition of the solution of the nonlinear Schrodinger equation.