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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 Fermis 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.

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.

This work presents a numerical study on the electronic and optical properties of modified Möbius squared potential well in the presence of static electric and magnetic fields. The potential well is formed within GaAs/AlGaAs hetero structures. Schrödinger's equation is solved within the framework of effective mass and envelope wave function approximations to get the wave functions and their corresponding energies of states. The optical absorption coefficients and relative refractive index changes are calculated via the expressions derived from the compact density matrix approach. The numerical results present strong blue shifts on the optical responses of modified Möbius squared potential well when the external electromagnetic fields are strengthening. [ABSTRACT FROM AUTHOR]

We present the transmittance spectra of one-dimensional photonic crystals embedded on two sides with air. The unit cell is composed of a YBa 2 Cu 3 O 7 - x superconductor as material A and a BaTiO 3 dielectric as material B . The transmittance of the formed structure (AB) N was studied using the transfer matrix method for different parameters such as layer widths ( d A and d B ), the angle of incidence, and temperature. Wavelength shifts delimiting the photonic bandgaps (PBGs) are discussed in detail. We found that these wavelengths shifted toward longer values (i.e., a redshift) as the size of the layers increased and the temperature increased. However, increasing the incidence angle shifts the wavelengths to shorter values (i.e., a blueshift). In the second part of this work, we discuss the impact of inserting semiconductor layers GaAs or Al x Ga 1 - x As with different bandgaps and varying the hydrostatic pressure, temperature, and aluminum concentration. We demonstrate that these semiconductors can also shift the PBGs and modify their widths; these findings constitute important results with implications for the design and realization of photonic filters. [ABSTRACT FROM AUTHOR]

In the present paper, the linear and nonlinear optical absorption coefficients and refractive index changes between the ground and the first excited states in double GaN/AlxGa(1-x)N quantum wells are studied theoretically. The electronic energy levels and their corresponding wave functions are obtained by solving Schrödinger-Poisson equations self-consistently within the effective mass approximation. The obtained results show that the optical absorption coefficients and refractive index changes can be red- and blue-shifted through varying the left quantum well width and the aluminum concentration xb2 of the central barrier, respectively. These structural parameters are found to present optimum values for carrying out the transition of 0.8 eV (1.55 μm). Furthermore, we show that the desired transition can also be achieved by replacing the GaN in the left quantum well with AlyGa(1-y)N and by varying the aluminum concentration yAl. The obtained results give a new degree of freedom in optoelectronic device applications such as optical fiber telecommunications operating at (1.55 μm). [ABSTRACT FROM AUTHOR]

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