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Öğe Binding Energies and Optical Properties of Power-Exponential and Modified Gaussian Quantum Dots(Mdpi, 2024) Alauwaji, Ruba Mohammad; Dakhlaoui, Hassen; Algraphy, Eman; Ungan, Fatih; Wong, Bryan M.We examine the optical and electronic properties of a GaAs spherical quantum dot with a hydrogenic impurity in its center. We study two different confining potentials: (1) a modified Gaussian potential and (2) a power-exponential potential. Using the finite difference method, we solve the radial Schrodinger equation for the 1s and 1p energy levels and their probability densities and subsequently compute the optical absorption coefficient (OAC) for each confining potential using Fermi's golden rule. We discuss the role of different physical quantities influencing the behavior of the OAC, such as the structural parameters of each potential, the dipole matrix elements, and their energy separation. Our results show that modification of the structural physical parameters of each potential can enable new optoelectronic devices that can leverage inter-sub-band optical transitions.Öğe GaAs Quantum Dot Confined with a Woods-Saxon Potential: Role of Structural Parameters on Binding Energy and Optical Absorption(Mdpi, 2023) Dakhlaoui, Hassen; Belhadj, Walid; Elabidi, Haykel; Ungan, Fatih; Wong, Bryan M.We present the first detailed study of optical absorption coefficients (OACs) in a GaAs quantum dot confined with a Woods-Saxon potential containing a hydrogenic impurity at its center. We use a finite difference method to solve the Schrodinger equation within the framework of the effective mass approximation. First, we compute energy levels and probability densities for different parameters governing the confining potential. We then calculate dipole matrix elements and energy differences, E1p-E1s, and discuss their role with respect to the OACs. Our findings demonstrate the important role of these parameters in tuning the OAC to enable blue or red shifts and alter its amplitude. Our simulations provide a guided path to fabricating new optoelectronic devices by adjusting the confining potential shape.Öğe Harnessing a Dielectric/Plasma Photonic Crystal as an Optical Microwave Filter: Role of Defect Layers and External Magnetic Fields(Mdpi, 2024) Dakhlaoui, Hassen; Belhadj, Walid; Elabidi, Haykel; Al-Shameri, Najla S.; Ungan, Fatih; Wong, Bryan M.We investigate the transmittance spectrum of a multichannel filter composed of dielectric (A) and plasma (P) materials in the microwave region within the transfer matrix formalism. Two configurations of the proposed filter are studied under the influence of an applied magnetic field: (1) a periodic structure containing (A/P)N unit cells surrounded by air and (2) the introduction of a second dielectric material (D) acting as a defect layer to produce an (AP)N/2/D/(AP)N/2 structure. Our findings reveal that in the periodic case, the number of resonant states of the transmittance increases with number N; however, the observed blue and red shifts depend on the intensity and orientation of the applied magnetic field. We present contour plots of the transmission coefficients that show the effect of the incident angle on the shifts of the photonic band gaps. Furthermore, we find that the introduction of a defect layer generates additional resonant states and merges the central resonant peak into a miniband of resonances. Moreover, we show that the number of resonant peaks and their locations can be modulated by increasing the unit cell number, N, as well as increasing the width of the inserted defect layer. Our proposed structures enable the design of novel photonic filters using magnetized plasma materials operating in the microwave region.
