فهرست مطالب

Optoelectronical Nanostructures - Volume:2 Issue: 2, Winter 2017

Journal of Optoelectronical Nanostructures
Volume:2 Issue: 2, Winter 2017

  • تاریخ انتشار: 1396/02/20
  • تعداد عناوین: 7
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  • Farhad Mehdizadeh *, Hamed Alipour-Banaei, Somaye Serajmohammadi Pages 1-10
    In this paper we combined an optical mixer via photonic crystal ring resonator to propose an all optical 1 to 2 decoder. The main idea used in this paper is based on controlling the optical behavior of the resonant ring via optical power intensity. We know that resonant wavelength of the photonic crystal ring resonator is very sensitive upon the refractive index of dielectric rods, on the other had the refractive index of dielectric materials depend on the optical power intensity. Therefore we can change the resonant wavelength of the resonator by increasing the optical power intensity up to adequate amount. The final structure has two output ports whose working states can be controlled by one input port. When I is OFF, the O1 port will turn ON and O2 is OFF, when I is ON, O1 turns OFF and O2 turns ON. The proposed structure works completely in optical domain without any electronics.
    Keywords: photonic crystal, optical decoder, Photonic band gap, Kerr effect
  • Tayebe Razegh, Vahid Setoodeh *, Siamak Pilban Jahromi Pages 11-18
    The influence of the particle size on magnetic behaviors of nickel oxide nanoparticles (NiO NPs) was reported. NiO NPs with a uniform particle size were synthesized via a facile sol-gel method, and various sizes of NiO NPs (11, to 49 nm) were achieved by calcination at various temperatures (400, to 700 °C). X-ray diffraction (XRD) analysis revealed that increasing the calcination temperature increased the crystallite size. TEM observations and XRD analysis were used to determine the particle size of the NiO NPs. The field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images showed flake-like morphologies, which consisted of interconnected nanoparticles with a porous channel. The magnetic properties of NiO NPs with different size were studied using vibrating sample magnetometer (VSM). The results suggested that the particle size plays an important role in magnetic property of NiO nanoparticles.
    Keywords: nickel oxide nanoparticle, sol–gel method, Magnetic behavior, X-ray Diffraction
  • Mohammad Yuonesi * Pages 19-28
    This paper shows the scattering mechanism at diluted magnetic semiconductors. The doped magnetic atom produces a scattering potential due to be coupled of itinerant carrier spin of host material with magnetic momentum of the doped magnetic atom. Formulas of scattering event were rewritten by the plane wave expansion and then the electron mobility of DMS was calculated. Calculations show Kondo effect on diluted magnetic semiconductors at nonmagnetic phase. Here has been supposed that the doping concentration is low and so the coupling coefficient between magnetic atoms is weak enough that DMS does not change its magnetic phase. In other words, material is on paramagnetic phase. For proofing our model, we have grown Zn0.99Mn0.01O with Sol-Gel route. Pure ZnO has also grown with this method for a comparison. Experimental results proved our theoretical model. Therefore as a result, at diluted magnetic semiconductors similar to diluted magnetic metals in nonmagnetic phase can observe kondod's effect .
    Keywords: diluted magnetic semiconductor, Kondo effect, scattering event, relation time, electrical resistivity
  • Tajedin Derikvand, Rajab Ali Kamyabi-Gol *, Mohammad Janfada Pages 29-40
    In this article a review on the definition of the X- ray transform and some of its applications in Nano crystallography is presented. We shall show that the X- ray transform is a special case of the Radon transform on homogeneous spaces when the topological group E(n)- the Euclidean group - acts on ℝ2 transitively. First some properties of the Radon transform are investigated then the relationship to texture analysis is briefly illustrated. Finally, some of its applications in material structure detection at the Nano scale are studied.
    Keywords: X- ray transform, Nano crystallography, homogeneous spaces
  • Zahra Ghaedi, Mehdi Hosseini *, Farrokh Sarreshtedari Pages 41-50
    Here, the population transfer between two specific levels of Cesium atom under the influence of chirped laser source has been numerically investigated. The main goal of this study is the engineering of the population transfer between the 62S1/2 and 62P1/2 levels of Cesium which is corresponding to its D1 transition line using a chirped laser source. Constructing the system Hamiltonian, as well as the initial and boundary conditions, the time-dependent Schrödinger equations are numerically solved and the population versus time for different physical parameters has been investigated. The final population of each state is calculated and discussed for changing the parameters such as laser intensity, laser frequency and chirping parameter. The results show that using the chirped laser source with tuned parameters, we can arbitrarily control the population of levels.
    Keywords: atomic population transfer, chirped laser, cesium atom, two-level system
  • Khadijeh Hemmati Kahradeh, Esmaiel Saievar-Iranizad *, Amir Bayat Pages 51-60
    In this study, carbon nano-micro spheres with tightly controllable size, regular and perfect shape, high yields and narrow size distribution were prepared simply from glucose and DI water as precursors using a hydrothermal method. By setting the initial concentration of glucose solution and changing the hydrothermal process time at a constant temperature of 160 °C, carbon spheres with various sizes were synthesized in a sealed autoclave. The relationship between the average carbon sphere size andhydrothermal process time has been discussed. By increasing the hydrothermal process time at a constant temperature (160 ° C) and a constant concentration of glucose solution 0.75 molar), carbon nano-micro spheres were obtained. The diameters of carbon nano-micro spheres synthesized in this study ranged from 90 nm to 4.5 μm. The obtained carbon nano-micro spheres were analyzed by different techniques including scanning electron microscopy (SEM), X-ray diffraction patterns (XRD), energy dispersive spectrometry (EDS) and Raman analysis. In addition, the existence of surface functional groups on carbon nano/micro spheres was characterized by Fourier transform infrared (FTIR) measurements.
    Keywords: Carbon microspheres, Carbon nanospheres, Hydrothermal process
  • Masoud Rezvani Jalal *, Mahshid Habibi Pages 61-70
    In this paper, the nonlinear rate equations governing a quantum dot laser is used to simulate the transient as well as the steady-state behaviors of the laser. Computation results show that the rate equations are capable of simulating true behavior of a quantum dot laser. Then, the pump rates of the rate equations (which show indirect electrical pumping of the quantum dots through a wetting layer) are changed so that they can show direct electrical pumping of the quantum dots. Simulation results predict that a quantum dot laser with direct pumping has much lower threshold current than the indirect one. It is also shown that duration time of the transient regime to reach steadystate operation is shorter in direct pumping.
    Keywords: Quantum Dot Laser, Direct Pumping, Indirect Pumping, Relaxation Oscillation