نشریه اپتوالکترونیک
سال دوم شماره 2 (پیاپی 6، پاییز 1396)

In this paper, we will study the effect of quantum confinement potential on the linear and nonlinear optical properties of a coaxial quantum wire at the presence of spin-orbit interaction and simultaneous influence of external electric and magnetic fields. To do this by solving the Schrödinger equation numerically, we calculate the energy eigenfunctions and eigenvalues of the system at the presence of spin-orbit interaction and external fields. Using the new eigenfunctions and eigenvalues, we will be able to calculate the absorption coefficient and refractive index and study the effect of quantum confinement and spin-orbit interaction on these optical properties.

In this paper, the transmission spectrum of a disordered binary one dimensional photonic crystal with a defect layer is investigated in two states, the disordered of thickness and the disordered of optical path length in both polarizations TE and TM. Then the displacement of defect mode wavelengths is studied. As we observed the defect mode shifts toward the larger wavelength when the degree of disorder get increased in both symmetric and asymmetric cases. Furthermore, in a given degree of disorder the defect mode shifts toward the shorter wavelength as the incident angles get increased. These displacements are more tangible in TE polarization. In the symmetric structure the height of defect modes gets decreased by increasing the degree of disorder.

In this study, optical properties of BaTiO3/SrTiO3/CaTiO3 compounds such as reflective index, extinction coefficient, absorption coefficient, reflectivity, energy loss spectrum and optical conductivity have been calculated and investigated in their stable phases, rhombohedral/ cubic/ orthohorombic phase with p4mm/m3m/pbnm space group respectively. The calculations have been conducted with pseudo-potential by GGA approximation in the frame work of Density Functional Theory. The obtained results for constant lattice after optimization, static dielectric constant, reflective index and plasma frequency have good accord with the experimental results and other theoretic studies. With respect to these quantities, perovskite oxides are good dielectrics. With respect to dielectic constants, and suitable optical absorbtion in the range of 4-12 eV, these perovskite oxides are good dielectrics. These compounds are transparent in energies above 13eV,and the maximum amount of conductivity occurs within 5eV. Also D coefficient calculated by Gladstone-Dale equation.

In this work, an electron which is strongly coupled to the LO-phonon in triangular quantum dots with Coulomb impurity is considered. First, the eigenenergies and eigenfunctions of the ground and the first-excited states of the electron are obtained using the Pekar variational method. We have studied entropy of the quantum dot qubit for different values of Coulomb impurity parameter, polaronic radius and electron-LO phonon coupling strength. Numerical analysis shows that the entropy has the oscillatory periodic evolution as function of the time due to the triangular form of the confinement. Also, the entropy increases with enhancing Coulomb parameter and polaronic radius.

In this paper, electron acceleration by a circularly polarized laser pulse in vacuum under the influence of constant magnetic field, combined constant axial and azimuthal magnetic fields and taper axial magnetic field has been studied. The effective parameters on energy gained by electron such as laser intensity, laser spot size, the value of azimuthal magnetic field and the tapered parameter of axial magnetic field are optimized. It was observed that by adding azimuthal magnetic field (about ) to constant axial magnetic field (about ) the maximum energy of electron can increase one and a half times (than the case of constant magnetic field) and reach to about . This is while tapered axial magnetic field with optimum tapered parameter    can keep the electron in acceleration phase for longer distance and reaches the electron to maximum energy about  with scattering angle about  degree.

Two-dimensionam transition-metal dichalcogenides (TMDC) layers with direct bandgaps have made a new horizon for application in photonics and electroptics. The presence of bandgap causes a significant absorption useful in photovoltaic devices. When these layers are located on a substrate that leads to a frequent optical reflection thus affect the absorption. Typically, SiO2 or Si or their combination as a substrate is used for these monolayers. In this paper, we used a transfer matrix method to study the absorption spectra of TMDC monolayers including MoSe2, WSe2, MoS2 and WS2 with the presence of SiO2/ Si substrate with different thicknesses of SiO2 layer. We found that using the SiO2 layer with a thickness of 90 nm in SiO2/ Si substrate does not change the general behavior of absorption and increases the absorption in some regions of the wavelength range.

Optical and magneto-optical responses of magnetophotonic crystals (MPCs) with a magnetic defect layer sandwiched between two dielectric Bragg mirrors have been investigated, which have potential application in integrated-optics devices. The Bragg mirrors are periodic multilayered films composed of SiO2 and Ta2O5 coatings. By introducing Ce:YIG magnetic defect layer, the enhancement of rotation angle and transmittance value, have been reported. By using of Finite Element Method (FEM), we have simulated the electric field profile in MPCs and investigated the effect of defect layer thickness on Faraday rotation angles. As a result of localization of light at magnetic defect layer and strong light-matter coupling in MPCs, the magneto-optical responses of these structures, are mostly increased near the PBG edges. The structure with a half wavelength optical thickness of defect layer is most suitable for practical applications.