نشریه اپتوالکترونیک
پیاپی 3 (زمستان 1395)

In this paper, Pulsed Laser Deposition (PLD) process at the presence of a background gas was simulated using the Monte Carlo method. Specifically, growth of aluminum metal in xenon background gas at the pressure of 50 mTorr was simulated. Target-to-substrate distances of 10, 15, 20, 25 and 30 mm are used in simulations. Spatial and energy information of the ions in the ablated plasma plume that forms in this method, as well as the sputtered ions from the growing thin film were collected. Thickness profile of the growing thin films was calculated using the spatial information of the transmitted and the sputtered ions. The results showed the possibility of dip formation at the center of the grown thin films with this method and its intensification by decreasing the target-to-substrate distance. The simulation results demonstrated the effective role of the sputtered ions from the growing thin film in the formation of this type of dips.

Solving of laser wakefield equations in the presence of external magnetic field, we observed that the dephasing length and final energy of accelerated electron by wakefield depend on polarization of laser pulse and applying direction of magnetic field. As for the case of applying magnetic field in the opposite direction of right polarized laser pulse propagation, the dephasing length with increment rather than other cases is about 5cm and final energy gained by electron reaches to about .

In this paper we studied the interaction of femtosecond laser pulse with atomic cluster of Ar. Ionization, heating and expansion of the cluster was the results of this interaction. Following this process, hot and energetic electrons and high charge state of ions were produced. By changing the characteristics of the laser and cluster, it is possible to achieve high efficiency products. Simulation of this work done with the numerical method in Nano plasma model and the evolution of charge state of ions for the various intensity of laser, different pulse shape and different initial ion density are calculated.

In this paper, the TM localized waves produced at the interface of homogeneous media and defective photonic crystals has been studied. The considered homogeneous medium can be a left-handed or a conventional material. It was found that for the conventional medium, in case of defect in the refractive index of photonic crystal layer, two type's waves as surface and defect localized waves can be created. Where, for the case of LH medium, only defect waves can be formed. Moreover dependence of ATR spectrum of the TM localized waves on the defect position and refractive index of defective layer has been discussed.

In this paper, we present an effective scheme to control molecular alignment and orientation by interaction of molecule with Two-color femtosecond laser pulse. For this purpose, we use numerical solution of the time - dependent Schrodinger equation for a linear molecule of carbon monoxide to achieve the control of Molecular Alignment and Orientation. Afterward, by using the Genetic algorithm, optimization on parameters of laser pulse take place. A suitable cost function was introduced in Genetic algorithm and showed that we can improve the intended control in this approach.

According to the recent remarkable developments of lead halide perovskite solar cells, investigation of the optical and electronical properties of perovskite structures seems necessary. In this paper, firstly Organic–inorganic CH3NH3PbX3 perovskite hybrids with X= Cl, Br and I were prepared by solution chemistry method. The effect of halogen atom on the electronical properties in this structure was studied experimentally. Our study concludes that the band gap energy can be tuned by varying the halogen atoms. Thus we believe that our studies will be beneficial for the fabrication of electronic and optical devises.

In this study, the transmission spectrum of an anisotropic photonic crystal using a transfer matrix method for both of polarization state TE and TM. We showedthat the Bragg gap, so called, anisotropic Bragg gap is created in transmission spectrum due to existence of anisotropic layer in structure. The results showed that the anisotropic Bragg gap strongly anisotropic layer and the optical axis of the incident beam angle dependent. The structure of the study can be considered as reflecting all of the frequencies to be used in some way.