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We present the numerical results obtained by the two dimensional diagonalisation method concerning the anisotropy and internuclear distance dependence of the electronic structure, total energy and diamagnetic susceptibility of an artificial hydrogen molecule ion confined in the quantum dot (QD). We have demonstrated the existence of the tunability of the diamagnetic susceptibility and energy levels of the D-2(+) complex by adjusting the QD size, distance between the impurity atoms and the anisotropy of the QD. Consequently, results reveal that a precise tuning of the electronic states and diamagnetic susceptibility of the system can be achieved by proper control of the anisotropy.

In this study, we present a theoretical simulation of the impact of applied external electric and magnetic fields on the nonlinear optical rectification (NOR), second harmonic generation (SHG), and third harmonic generation (THG) in typical GaAs/Ga0.6 Al0.4 As asymmetric double triangular quantum wells. At first, we have calculated the wave functions and the subband energy levels for the lowest bounded four states confined within the structure by solving the Schrödinger equation using the diagonalization method within the framework of the effective mass and single parabolic band approximations. Then, the analytical expressions of the NOR, SHG, and THG are obtained using compact density matrix approach via iterative method. According to the numerical results, it is concluded that electric and magnetic fields play a vital and important role in the electronic and optical properties of the system and they can be used to adjust the intersubband transitions and change the associated optical sensitivities.

Using the two-dimensional diagonalization method and the effective mass approximation, the electronic structure and intersubband optical absorption of the singly ionized double donor complex confined in a Gaussian quantum dot have been investigated. The obtained results indicated that the quantum dot size and internuclear distance significantly affect the binding energy, dissociation energy, equilibrium distance, and amplitude of the optical absorption. Also, we conclude that a significant increase in the amplitude of the dipole-related matrix element and the energy difference between the two lowest-lying energy states is observed when the distance between the donor atoms is in the order of the quantum dot size. Consequently, the electronic and optical properties can be precisely tuned by controlling the system's size and the internuclear distance.

In this study, the electronic and optical properties of single or core/shell quantum dots, which are formed depending on the parameters in the selected Konwent potential, are investigated. Namely, the effects of the size and geometric shapes of quantum dots on the binding energy of the on-center donor impurity, the total absorption coefficient and refractive index which are including transitions between the some confined states, and the electromagnetically induced transparency between the lowest six confined states related to the donor impurity are investigated. We have used the diagonalization method by choosing a wave function based on the Bessel and Spherical Harmonics orthonormal function to find the eigenvalues and eigenfunctions of the electron confined within the quantum dots which have different types mentioned above. To calculate the optical absorption coefficients and electromagnetically induced transparency related to shallow-donor impurity, a two- and three-level approach in the density matrix expansion is used, respectively.

Ground-state binding energy and optical absorption coefficient of exciton in a symmetric double inverse parabolic quantum well system in the presence of external electric and magnetic fields are investigated theoretically. Numerical calculations have been carried out with the variational technique considering the single-band effective mass approximations. Results reveal that the excitonic binding energy and interband optical absorption depend on significantly on the geometrical and structural parameters defining carriers’ double inverse parabolic confinement potential, the aluminum concentration at the well center, the electric field, and the magnetic field. The exciton binding energy is a decreasing (increasing) function of the electric field (magnetic field). The increase in aluminum concentration creates a blueshift at the resonance peak positions. As a result, the tunability of the excitonic effects is expected to be of importance in developing stable and high-efficiency nanoscale excitonic optoelectronic devices.

This study reports a theoretical investigation on the electronic spectrum and the photoionization cross section of a singly ionized double donor complex D-2(+) confined in a two-dimensional quantum dot with Gaussian confinement potential. Using the diagonalization method and the effective mass approach, the energy spectrum, binding energy, and photoionization cross section of the D-2(+) complex were obtained for different quantum dot sizes and internuclear distances. The numerical results obtained reveal that the size of the geometric confinement and the configuration of the donor atoms significantly affect the binding energy, equilibrium distance and photoionization cross section of the D-2(+) complex. As a result, the electronic spectrum and optical responses of the artificial molecule D-2(+) complex can be fine-tuned simply by controlling the confinement size and impurity configuration. Also, we conclude that a significant increase in the amplitude of the photoionization cross section is observed when the donor atoms are symmetrically positioned on the x-axes. In addition, the exact convergence of the results obtained in the limiting case to the known results demonstrated the suitability of the method used in this study.

Using the compact density matrix scheme and the effective mass approximation, we study the influence of positiondependent electron and heavy-hole mass distributions on the impurity-related electronic properties, excitonic binding, and intersubband electron transitions in a two-dimensional quantum dot with Gaussian potential. The electronic structure has been obtained by using the two-dimensional diagonalization method. The obtained results show the significant influence of the functional form of the spatial mass distribution and structural geometry on the accurate determination of the impurity-related electronic structure, optical response, electron–hole overlap, and, therefore, the carrier lifetimes in the optoelectronic devices based on quantum dots.

In this paper, we calculated the electronic and optical absorption coefficient of the Manning-like double quantum well under the external applied electric and magnetic fields. To calculate the linear and third-order nonlinear optical absorption coefficients is used two-level approach in the density matrix expansion. The findings show that the electronic structure can be adjusted by changing the well and barrier widths, the well depth, the coupling between the wells as well as applied external field intensities. In addition, direct and indirect exciton states in asymmetric double quantum wells with Manning-like potential under electric field are compared with experimental studies. From the obtained results, it is concluded that the Manning-like potential is an excellent strategy for modeling electronic states in asymmetric double quantum wells with steep potential barriers and also the Manning-like potential allows modeling interdiffusion effects at the interfaces of multiple heterostructures.

In this study, the electronic and optical properties of single or core/shell quantum dots, which are formed depending on the parameters in the selected Konwent potential, are investigated. Namely, the effects of the size and geometric shapes of quantum dots on the binding energy of the on-center donor impurity, the total absorption coefficient and refractive index which are including transitions between the some confined states, and the electromagnetically induced transparency between the lowest six confined states related to the donor impurity are investigated. We have used the diagonalization method by choosing a wave function based on the Bessel and Spherical Harmonics orthonormal function to find the eigenvalues and eigenfunctions of the electron confined within the quantum dots which have different types mentioned above. To calculate the optical absorption coefficients and electromagnetically induced transparency related to shallow-donor impurity, a two- and three-level approach in the density matrix expansion is used, respectively.

© 2021 Elsevier LtdIn this work, we perform a theoretical investigation on the effect of position-dependent effective mass on binding energy and optical absorption coefficient for donor impurities in single and double quantum wells defined by Konwent potential. We have used the diagonalization method by choosing a wave function based on the trigonometric orthonormal base functions that are solutions of an infinite square quantum well to get the energy spectrum of the system, the variational method for impurity binding energy is used and also linear absorption coefficient is deduced from the density matrix approach and perturbation expansion method. Numerical results reveal that impurity binding energy as well as the linear optical absorption coefficient are remarkably affected by the confinement potential parameters, position of an impurity and the approach used for the effective electron mass. Moreover, it is seen that with an appropriate choice of the structure parameters and position dependence effective mass distribution, the optical response of the system can be tailored in a controllable manner.

We investigate the energy states of confined electrons in doped quantum structures with Razavy-like confining potentials. The theoretical investigation is performed within the effective mass and parabolic band approximations, including the influence of externally applied electric and magnetic fields. First, we analyze the case of a Razavy quantum well and determine its conduction subband spectrum, focusing on the lowest energy levels and their probability densities. These properties have been numerically determined by self-consistently solving the coupled system of Schr\"{o}dinger, Poisson, and charge neutrality equations. Doping is introduced via an on-center $\delta$-like layer. In order to evaluate the associated total (linear plus nonlinear) optical absorption coefficient (TOAC), we have calculated the corresponding diagonal and off-diagonal electric dipole matrix elements, the main energy separation, and the occupancy ratio which are the main factors governing the variation of this optical response. A detailed discussion is given about the influence of doping concentration as well as electric and magnetic fields, which can produce shifts in the light absorption signal, towards either lower or higher frequencies. As an extension of the self-consistent method to a two-dimensional problem, the energy states of quantum wire system of circular cross section, with internal doping and Razavy potential have been calculated. The response of eigenvalues, self-consistent potentials and electron densities is studied with the variation of $\delta$-doping layer width and of the donor density. Finally, the origin of Friedel-like oscillations, that arise in the density profile, generated by the occupation of internal and surface electronic states has been explained.

Using the two-dimensional (2D) diagonalisation method, the impurity-related electronic states and optical response in a 2D quantum dot with Gaussian confinement potential under nonresonant intense laser field are investigated. The effects of a hydrogenic impurity on the energy spectrum and binding energy of the electron and also intersubband optical absorption are calculated. The obtained numerical results show that the degeneracies of the excited electron states are broken and the absorption spectrum exhibits a redshift with the values of the laser field. The findings indicate a new degree of freedom to tune the performance of novel optoelectronic devices, based on the quantum dots and to control their specific properties by means of intense laser field and hydrogenic donor impurity. Using the same Gaussian confinement model, the electronic properties of a confined electron in the region of a spherical quantum dot are studied under the combined effects of on-centre donor impurity and a linearly polarised intense laser radiation. The three-dimensional problem is used to theoretically model, with very good agreement, some experimental findings reported in the literature related to the photoluminescence peak energy transition.

This study set out to introduce the optical nonlinearities of a intense laser-driven two-dimensional quantum ring subjected to external uniform magnetic field. Inclusion of the effect of non-resonant, high-frequency THz laser radiation is realised by the laser-dressed potential, whereas the total optical absorption coefficients, total relative refractive index changes and third-harmonic generation (THG) coefficient are inferred from the scheme of compact density-matrix formalism and iterative method. Our results reveal that the laser field smoothens the antidot region of the ring that consequences with remarkable modifications in the electronic structure and correspondingly the optical response of the system. We have found that the height and location of the resonant peaks of total optical absorption coefficient, total relative refractive index changes and THG coefficient can be controlled by the externally applied fields and system parameters. The tunability of the intersubband transitions could be beneficial for practical device application relying on the electronic optical transitions.

In this work, we theoretically investigate the anisotropy effects on impurity states and optical transitions in quantum dots. In particular, we investigate the role of the impurity position on the binding energy and optical response of the ellipsoidal quantum dots. Theoretical calculations have been carried out using the effective mass approach. The results show that the impurity binding energies and the optical transitions between the impurity states are significantly affected by the impurity position and aspect ratio of the ellipsoidal quantum dots. In general, we conclude that the anisotropy degree of quantum dots can be used as a tunability parameter for the electronic structure and optical response of the systems based on the quantum dots.

In this study, we present a detailed theoretical investigation of the effect of an externally applied magnetic field on the energy states 1s, 1p, 1d and 1f in the spherical quantum dot with finite and infinite confinement potentials. For both finite and infinite spherical quantum dot, the first four electron energies, Zeeman transition energies between these electronic states and optical absorption coefficients between the related states with and without magnetic field are investigated. The results show that the confinement potential, magnetic field and dot radius have a strong effect on energy states, Zeeman transition energies and absorption coefficients especially in the large dot radii. In the small dot radii, energy levels are relatively insensitive to the magnetic field because the spatial confinement of the electron prevails over the magnetic confinement. As Delta m changes from -1 to +1, the peak positions of the optical absorptions shift to higher energy values (blue shift). The absorption peaks for the infinite quantum dot are localised in higher photon energies those that of the finite quantum dot. The magnetic field causes that the degeneration of energies to be removed and the peak positions of transitions corresponding to Delta m = +1 shift towards to blue in contrast to the cases of Delta m = -1 and Delta m = 0.

Using the effective mass and parabolic band approximations, we investigated the position-dependent effective mass and non-resonant intense laser field effects on the first and third-order corrections of the absorption and relative changes of the refraction index coefficients for intersubband transition in Razavy-like quantum wells. Calculations have been extended to the spherical Razavy-like quantum dots electronic structure. We have shown that depending on the combinations of the Razavy-like potential parameters, the quantum wells can evolve from parabolic confinement in an isolated quantum well to a configuration of two coupled quantum wells. We have shown that in general the transition energies (dipole matrix elements) between the ground state and the first excited state: i) are decreasing (increasing) functions of M-parameter, ii) are increasing (decreasing) functions of A-parameter, iii) they increase (decrease) when considering the position-dependent effective mass effects, and iv) are increasing (decreasing) functions of the intense laser field parameter. In the case of the optical absorption and relative changes in the refractive index coefficients, we have shown blueshifts or redshifts by changing the A-, M-, and α0-parameters and by considering the effects of the position-dependent effective mass. In spherical quantum dots, we have shown that with an appropriate value of A- and M-parameters the system can evolve from a spherical quantum dot with infinite parabolic potential.

In this study, the binding energies of an on-center and off-center hydrogenic donor impurity in a spherical quantum dot with finite confinement potential under an applied external magnetic field are investigated in detail by using the matrix diagonalization method in the effective mass approximation. Depending on the calculated energies and wave functions, the linear, third-order nonlinear and total optical absorption coefficients between the ground and several excited states are examined by the iterative method in the compact density matrix approximation for the two-level system. The combined effect of donor position, magnetic field and dot size on binding energies and optical absorption coefficients is observed. The results show that these effects cause significant changes on donor binding energy and optical absorption coefficients.

WOS: 000457720900013, We have investigated the binding energies of the s-symmetric ground and first excited shallow donor impurity states and the total 1s -> 2s absorption coefficient, including the first and third order corrections, in "12-6" tuned GaAs/GaAlAs double quantum well as a function of the impurity position, size of the structure, and the electric and magnetic field intensities. The obtained results show that the electronic and optical properties of tuned GaAs/GaAlAs double quantum well can be adjustable by an appropriate choice of the sample geometry, material parameters and applied external fields which will lead to new potential applications in optoelectronics., Colombian Agency: CODI-Universidad de Antioquia (Estrategia de Sostenibilidad de la Universidad de Antioquia); Colombian Agency: Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD-exclusive dedication project 2017-2018); Cumhuriyet University (CUBAP) [F-557], This research was partially supported by Colombian Agencies: CODI-Universidad de Antioquia (Estrategia de Sostenibilidad de la Universidad de Antioquia) and Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD-exclusive dedication project 2017-2018). This work used resources of the Centro Nacional de Processamento de Alto Desempenho em Sao Paulo (CENAPAD-SP). The authors are grateful to The Scientific Research Project Fund of Cumhuriyet University (CUBAP) under the project number F-557.

WOS: 000462810600047, In the present paper, we theoretically investigate the effect of applied external fields, such as electric, magnetic, and intense terahertz laser fields on the optical absorption and the relative refractive index change coefficients of triple delta-doped quantum well structures. To investigate the applied external field effects, we perform the calculation of the allowed subband energy levels and their corresponding eigen-functions using the diagonalization method within the framework of the effective-mass approximation. The effects of the applied external fields on the nonlinear optical properties of the quantum well structure are treated within the compact-density-matrix approach via the iterative method. The numerical results obtained are presented for two different values of electric, magnetic, and intense terahertz laser fields. These results show that changing the intensity of the external electric, magnetic, and intense terahertz laser field. It is concluded that the nonlinear optical response of the triple delta-doped structure can be significantly changed through the changes in the configuration of the external probes.

WOS: 000453499500082, We present a theoretical study on the linear and nonlinear optical properties in AlrGa1-rAs/GaAs asymmetric multiple step quantum wells (AMSQW) under the effects of a non-resonant intense laser field (ILF), electric, and magnetic field. Calculations are for the linear optical absorption and refractive index relative changes combined with the second and third harmonic generation. The potential profile is constructed as a function of the Aluminum concentration, so that the heterostructure has four steps of different concentration, width and height. The energy levels and corresponding wavefunctions are obtained by solving the Schordinger equation, for an electron, in the envelope function approach, with parabolic bands, and the effective mass approximations. The results show that variations in ILF, electric field and magnetic field have significant influences on the magnitude and peak energy positions of the SHG and THG coefficients. Therefore, we can conclude that the effects of ILF, electric and magnetic fields can be used to tune and control the SHG and THG in the range of the terahertz electromagnetic spectrurn., CODI-Universidad de Antioquia (Estrategia de Sostenibilidad de la Universidad de Antioquia); CODI-Universidad de Antioquia (project : "Efectos opticos intersubbanda, no lineales de segundo orden y dispersion Raman, en sistemas asimetricos de pozos cuanticos acoplados"); CODI-Universidad de Antioquia (project: "Efectos de capas delta dopadas en pozos cuanticos como fotodetectores en el infrarrojo"); Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD exclusive dedication project 2018-2019); Universidad EIA; Universidad de Antioquia; Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (ALM exclusive dedication project 2018-2019), This research was partially supported by Colombian Agencies: CODI-Universidad de Antioquia (Estrategia de Sostenibilidad de la Universidad de Antioquia and projects: "Efectos opticos intersubbanda, no lineales de segundo orden y dispersion Raman, en sistemas asimetricos de pozos cuanticos acoplados" and "Efectos de capas delta dopadas en pozos cuanticos como fotodetectores en el infrarrojo") and Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD exclusive dedication project 2018-2019 and ALM exclusive dedication project 2018-2019). The authors are grateful to the Universidad EIA and Universidad de Antioquia for its financial support through the EIA-UdeA-UdeM-project "Generacion de segundo armonico, rectificacion optica y dispersion Raman entre estados electronicos en pozos cuanticos acoplados". RLR and JPGP are grateful to Semillero de Investigacion Universidad EIA "Nanoestructuras Semiconductoras".

WOS: 000449621100040, A theoretical study of the effects of non-resonant intense laser field on the optical response in a Gaussian potential quantum well is performed in the framework of the effective mass approximation. The obtained results indicate that, the depth and range of the considered confinement potential and intense laser field intensity has a significant effect on the optical properties in Gaussian potential quantum wells. Also it was found that the laser field is more effective on the optical response in Gaussian potential quantum wells with smaller range.

Within the structure of parabolic band and effective-mass approximations, the effects of magnetic and intense terahertz laser fields on the donor impurity-associated photoionization cross-section and nonlinear optical properties in delta-doped quantum well wires are studied using the variational method. The binding energy and photoionization cross-section as functions of doping concentrations, magnetic and terahertz laser fields are computed. The linear, third-order nonlinear and the corresponding total absorption coefficients and relative refractive index changes with a function of incoming photon energy for various doping concentrations, magnitude of terahertz laser and magnetic fields are investigated. The numerical results bring out that the donor impurity binding energy, photoionization cross-section, and nonlinear optical properties in the structure are strongly dependent on doping concentrations. In addition, it has been observed that the magnetic and intense terahertz laser fields cause considerable changes in the binding energy, photoionization cross section and nonlinear spectral properties of the system.

This article reports a theoretical study of the intersubband optical properties in quantum wells with modified Manning potential considering the effects of position-dependent effective mass. Calculations are made in the effective mass and parabolic band approximations. The electronic spectrum, dipole matrix element for intersubband transitions, optical absorption coefficient, and refractive index coefficient are reported. Modifying the Manning potential’s three parameters is a useful tool to simulate single and multiple quantum wells. The solution of the eigenvalues differential equation is implemented through the expansion technique based on orthonormal trigonometric functions. Such a procedure is contrasted with those obtained from solving the problem by using the finite element method. Both methods of solving the differential equations report results with excellent agreement between them and the possibility of achieving the desired precision in the spectrum energy and the wave functions and the calculated observable. The results presented here are useful for studying isolated and multiple quantum wells where interdiffusion effects are involved in the interfaces. The findings demonstrate the versatility of the modified Manning potential since, by properly manipulating its three parameters, it is possible to tune the spectrum of energies with potential applications in next-generation optoelectronic devices.

In this paper we are reporting the computation for the Nonlinear Optical Rectification (NOR) and the Second and Third Harmonic Generation (SHG and THG) related with electronic states of asymmetric double Si- δ -doped quantum well in a GaAs matrix when this is subjected to an in-plane ( x -oriented) constant magnetic field effect. The work is performed in the effective mass and parabolic band approximations in order to compute the electronic structure for the system by a diagonalization procedure. The expressions for the nonlinear optical susceptibilities, χ 0 ( 2 ) , χ 2 ω ( 2 ) , and χ 3 ω ( 3 ) , are those arising from the compact matrix density formulation and stand for the NOR, SHG, and THG, respectively. This asymmetric double δ -doped quantum well potential profile actually exhibits nonzero NOR, SHG, and THG responses which can be easily controlled by the in-plane ( x -direction) externally applied magnetic field. In particular we find that for the chosen configuration the harmonic generation is in the far-infrared/THz region, thus and becoming suitable building blocks for photodetectors in this range of the electromagnetic spectra.

WOS: 000411546800020, The effects of electric and magnetic fields on the second and third harmonic generation coefficients in a Morse potential quantum well are theoretically studied. The energy levels and corresponding wave functions are obtained by solving the Schrodinger equation for the electron in the parabolic band scheme and effective mass approximations and the envelope function approach. The results show that both the electric and the magnetic fields have significant influence on the magnitudes and resonant peak energy positions of the second and third harmonic generation responses. In general, the Morse potential profile becomes wider and shallower as gamma-parameter increases and so the energies of the bound states will be functions of this parameter. Therefore, we can conclude that the effects of the electric and magnetic fields can be used to tune and control the optical properties of interest in the range of the infrared electromagnetic spectrum. (C) 2017 Elsevier B.V. All rights reserved., CODI-Universidad de Antioquia (Estrategia de Sostenibilidad de la Universidad de Antioquia); Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD); Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (ALM); Universidad EIA; Universidad de Antioquia, This research was partially supported by Colombian Agencies: CODI-Universidad de Antioquia (Estrategia de Sostenibilidad de la Universidad de Antioquia) and Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD and ALM exclusive dedication project 2016-2017). CAD and RLR are grateful to Universidad EIA and Universidad de Antioquia for financial support through the EIA-UdeA-UdeM-projects "Desarrollo de fotodetectores en el infrarrojo usando pozos cuanticos ajustables con dopamiento delta dentro del pozo".

In this paper, we have investigated the effects of the non-resonant intense laser field on the electronic and optical properties such as linear, nonlinear and the total optical absorption coefficient and refractive index change for transitions between two lower-lying electronic states in the GaAs-based δ -doped quantum well. Within the effective mass approximation, we calculated the eigenvalues and corresponding eigenfunctions as a function of the intense laser parameter by solving the Schrodinger equation in the laser-dressed confinement potential. The analytical expressions of the linear and third-order non-linear optical absorption coefficients and refractive index changes are obtained by using the compact-density matrix formalism. The obtained results show that the separation between ground and first excited energy levels in the δ -doped quantum well decreases in energy by the increase of the laser field intensity and this effect leads to an optical red-shift in the intersubband transitions. This behavior gives us a new degree of freedom in tunability of different device applications based on the optical transitions.

WOS: 000398055300002, We investigate theoretically the intense laser-induced optical absorption coefficients and refractive index changes in a two-dimensional quantum pseudodot system under an uniform magnetic field. The effects of non-resonant, monochromatic intense laser field upon the system are treated within the framework of high-frequency Floquet approach in which the system is supposed to be governed by a laser-dressed potential. Linear and nonlinear absorption coefficients and relative changes in the refractive index are obtained by means of the compact-density matrix approach and iterative method. The results of numerical calculations for a typical GaAs quantum dot reveal that the optical response depends strongly on the magnitude of external magnetic field and characteristic parameters of the confinement potential. Moreover, we have demonstrated that the intense laser field modifies the confinement and thereby causes remarkable changes in the linear and nonlinear optical properties of the system.

In the present work, we are interested in calculating anisotropy dependence of the optical response in an ellipsoidal quantum dot with a hydrogenic impurity in the presence of high-frequency intense laser field within the framework of the effective mass approximation. The effects of the anisotropy of the system and laser field intensity on the energy levels and the respective impurity binding energies are calculated. It is shown that the electrostatic interaction between the electron and the impurity atom becomes the weakest when the structure has a spherical symmetry and in contrast to the 1s-like state, the binding energy of the 2pz-like state increases with the laser field intensity for all values of the anisotropy parameter considered. The results show that the anisotropy degree plays a fundamental role in determining the optical response of the ellipsoidal quantum dot. © 2019 Elsevier B.V.

WOS: 000457429700005, A detailed theoretical study on the electron-related optical responses in triple delta-doped GaAs quantum wells in the presence of non-resonant, monochromatic intense laser field is presented. For this purpose, we first obtained the bound subband energy levels and their corresponding envelope wave functions of the structure for different central doping concentrations within the effective-mass approximation. Then, we calculate the effect of the non-resonant intense laser field on the optical properties of this structure using the compact-density-matrix approach via the iterative method. We found that the optical absorption coefficients and refractive index changes in the triple delta-doped GaAs quantum well can be modulated by changing the central doping concentration and the intensity of the non-resonant, monochromatic laser field. In addition, it is shown that a sufficiently intense laser field suppresses the multiple quantum well configuration towards a single potential well one and the optical response becomes practically independent of the delta-doping concentration.

WOS: 000394635200076, In this work we shall present a study of inelastic light scattering involving inter-subband electron transitions in coupled GaAs-(Ga,AI)As quantum wells. Calculations include the electron related Raman differential cross section and Raman gain. The effects of an external nonresonant intense laser field are used in order to tune these output properties. The confined electron states will be described by means of a diagonalization procedure within the effective mass and parabolic band approximations. It is shown that the application of the intense laser field can produce values of the intersubband electron Raman gain above 400 cm(-1). The system proposed here is an alternative choice for the development of Al chi Ga1-chi As semiconductor laser diodes that can be tuned via an external nonresonant intense laser field. (C) 2017 Elsevier B.V. All rights reserved., Colombian Agencies: CODI-; Mexican PRODEP for a Posdoctoral Grant [09/2016-08/2017]; Universidad EIA; Universidad de Antioquia through the EIA-UdeA-UdeM-project "Propiedades Opto-electronicas de sistemas altamente confinados: Una aproximaciOn teorica"; Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD and ALM-exclusive dedication projects 2016-2017), This research was partially supported by Colombian Agencies: CODI-Universidad de Antioquia (Estrategia de Sostenibilidad de la Universidad de Antioquia and projects: "Propiedades opticas de impurezas, excitones y moleculas en puntos cuanticos autoensamblados" and "On the way to development of new concept of nanostructure-based THz laser") and Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD and ALM-exclusive dedication projects 2016-2017). AT thanks Mexican PRODEP for a Posdoctoral Grant 09/2016-08/2017. CAD and RLR are grateful to Universidad EIA and Universidad de Antioquia for financial support through the EIA-UdeA-UdeM-project "Propiedades Opto-electronicas de sistemas altamente confinados: Una aproximaciOn teorica".

WOS: 000386644500026, The electron states in a two-dimensional quantum dot ring are calculated in the presence of a donor impurity atom under the effective mass and parabolic band approximations. The effect of an externally applied electric field is also taken into account. The wavefunctions are obtained via the exact diagonalization of the problem Hamiltonian using a 2D expansion within the adiabatic approximation. The impurity-related optical response is analyzed via the optical absorption, relative refractive index change and the second harmonics generation. The dependencies of the electron states and these optical co-efficients with the changes in the configuration of the quantum ring system are discussed in detail. (C) 2016 Elsevier B.V. All rights reserved.

WOS: 000376213000005, We investigate the effects of Rashba spin-orbit interaction on the optical absorption coefficients and refractive index changes associated with transitions between the first two lower-lying electronic levels in double quantum wire. The wire system represented by a symmetric, double quartic-well confinement potential is subjected to a perpendicular magnetic field. The analytical expressions of the linear and third-order nonlinear optical absorption coefficients and refractive index changes are obtained by using the compact density matrix formalism and iterative scheme. Optical properties are investigated as a function of structural parameter, magnetic field, Rashba spin-orbit interaction and photon energies. Numerical results reveal that competing effects between spin-orbit interaction and magnetic field modify strongly the optical properties and can be altered by these parameters. (C) 2016 Elsevier Ltd. All rights reserved., Scientific and Technological Research Council of Turkey [TUBITAK BIDEB 2211], The authors Y. Karaaslan and B. Gisi would like to thank the Scientific and Technological Research Council of Turkey (TUBITAK BIDEB 2211) for doctoral scholarship.

WOS: 000373091900016, Electronic structure and optical properties in equilateral triangular GaAs/Al0.3Ga0.7As quantum dots are studied extensively. The effects of donor and acceptor impurity atoms positioned in the orthocenter of the triangle, as well as of the external DC electric field are taken into account. Binding energies of the impurity, exciton energies, interband photoluminescence peak positions as well as linear and non-linear optical properties in THz range caused by transitions between excitonic states are calculated and discussed. (C) 2015 Elsevier B.V. All rights reserved.

WOS: 000372559600045, We investigate the electronic structure, spin and transport properties of double quantum wires formed by a symmetric, double quartic-well potential subjected to an in-plane magnetic field by taking into account Rashba and Dresselhaus spin-orbit couplings. The energy dispersion relation of the system is analyzed for different strengths of spin-orbit interactions, magnitude and direction of magnetic field. Our numerical results reveal that the existence of aforementioned parameters modifies strongly the energy band structure, introduces a wave vector dependence to energies and also leads to crossings and anticrossings between subbands. This complex structure of energy dispersion gives rise to the appearance of square-wave like oscillations in the conductance. The spin-orbit couplings, magnetic field, potential profile and Fermi energy of an electron significantly affect the depth and width of conductance steps. Moreover, we found that the competing effect between spin-orbit couplings and magnetic field leaves its marks on the spin texturing. (C) 2015 Elsevier Ltd. All rights reserved., Scientific and Technological Research Council of Turkey [TUBITAK BIDEB 2211], The authors B. Gisi and Y. Karaaslan would like to thank the Scientific and Technological Research Council of Turkey (TUBITAK BIDEB 2211) for doctoral scholarship. This work has been completed at the Dokuz Eylul University, Graduate School of Natural and Applied Sciences and is the subject of the forthcoming Ph.D. Thesis of Bircan Gisi.

WOS: 000457753000024, PubMed ID: 30723242, The features of the electron energy spectrum in eccentric two-dimensional GaAs-AlGaAs quantum rings of circular shape are theoretically investigated taking into account the effect of externally applied magnetic and intense laser fields. Analytical expressions for the laser-dressed confining potential in this kind of quantum ring geometry are reported for the first time. Finite element method is used to solve the resulting single-particle effective mass two-dimensional partial differential equation. It is shown that the allowed level spectrum is greatly influence by the external probe as well as by the breaking of geometric symmetry related to the changes in eccentricity. In presence of an intense laser field, the conduction band confining profile suffers strong modifications along the structure, with an additional contribution to symmetry breaking. These modifications of electronic quantum states reflect in the intraband optical absorption. Accordingly, the features of the intraband transitions are discussed in detail, revealing the significant influence of the magnetic field strength and laser field intensity and polarization, together with eccentricity, in the allowing of ground-to-excited states transitions and their corresponding intensities., Universidad EIA; CODI-Universidad de Antioquia (Estrategia de Sostenibilidad de la Universidad de Antioquia); CODI-Universidad de Antioquia (project "Efectos de capas delta dopadas en pozos cuanticos como fotodetectores en el infrarrojo"); CODI-Universidad de Antioquia (project "Efectos opticos intersubbanda, no lineales de segundo orden y dispersion Raman, en sistemas asimetricos de pozos cuanticos acoplados"); Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD-exclusive dedication project 2018-2019); Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (ALM-exclusive dedication project 2018-2019); Colombian Agency El Patrimonio Autonomo Fondo Nacional de Financiamiento para la Ciencia, la Tecnologa y la Innovacion, Francisco Jose de Caldas-COLCIENCIAS; Mexican Conacyt [206772]; Universidad de Antioquia, J.A. Vinasco acknowledges the support and fruitful cooperation with Prof. Dr. A. Radu during his doctoral stay at the Department of Physics, "Politehnica" University of Bucharest, where part of this work was done. This research was partially supported by Colombian Agencies: Universidad EIA, CODI-Universidad de Antioquia (Estrategia de Sostenibilidad de la Universidad de Antioquia and projects "Efectos de capas delta dopadas en pozos cuanticos como fotodetectores en el infrarrojo" and "Efectos opticos intersubbanda, no lineales de segundo orden y dispersion Raman, en sistemas asimetricos de pozos cuanticos acoplados"), and Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD-exclusive dedication project 2018-2019 and ALM-exclusive dedication project 2018-2019). This work used resources of the Centro Nacional de Processamento de Alto Desempenho em Sao Paulo (CENAPAD-SP). J.A. Vinasco acknowledges the doctoral financial support from the Colombian Agency El Patrimonio Autonomo Fondo Nacional de Financiamiento para la Ciencia, la Tecnologa y la Innovacion, Francisco Jose de Caldas-COLCIENCIAS. M.E. Mora-Ramos acknowledges support from Mexican Conacyt through Grant 206772. The authors are grateful to the Universidad EIA and Universidad de Antioquia for financial support through the EIA-UdeA-UdeM-project "Generacion de segundo armonico, rectificacion optica y dispersion Raman entre estados electronicos en pozos cuanticos acoplados".

WOS: 000454472000163, In the present study we have investigated the bound energy levels and intersubband optical transitions in the Tietz-Hua quantum well for a spatially varying effective mass distribution. The energy levels and eigenfunctions are obtained by solving the effective mass equation through a variational approach. The obtained numerical calculations show that the spatially varying effective mass has a significant effect on the subband energies and transitions between the sub bands in the Tietz-Hua quantum well. We conclude that, the energy levels and hence energy differences between the subband states decrease with increasing the stability and uniformity of the effective mass and eventually converge to the results of the constant effective mass. Furthermore, it was found that the size of the Tietz-Hua quantum well has an important effect on optical responses based on the intersubband transitions and additionally, the asymmetrical form of the Tietz-Hua quantum well is more predominant in stable and uniform effective mass case.

In this present work, the effect of non-resonant, mono-chromatic intense laser field (ILF) on the linear and nonlinear optical properties of a semi-exponential quantum well (SEQW) is investigated theoretically within the effective-mass and envelope wave function approach. The bound subband energy levels and their envelope wave functions of the structure are calculated by using the diagonalization method. The optical properties of the system are obtained by using the compact-density matrix approach. The obtained numerical results show that the applied ILF and structure parameters have a significant impact on the optical properties of these structures, such as the linear, third-order nonlinear and total absorption coefficients and relative refractive index changes. Furthermore, from the findings of this study, it has been concluded that the linear and nonlinear optical properties in a SEQW under the ILF can be tuned by changing structure parameters, such as the effective range and depth of the system. © 2019 Elsevier GmbH

WOS: 000465157600059, Binding energies of the lowest two s-symmetric impurity states and linear, third order nonlinear, and total optical absorption coefficients corresponding to the 1s -> 2s transitions for electrons in a Morse quantum well are investigated. Influence of a non-resonant intense laser field is considered for different values of the structure parameter, impurity position, and laser field intensity. In order to find the eigenvalues and eigenfunctions of the unbound electron confined within the Morse quantum well under the intense laser field, the time independent Schrodinger equation is solved by using the effective mass and parabolic band approximations. The impurity binding energy is determined by means of a variational procedure, using hydrogen-like trial wave functions, and the optical response is treated with the use of a two-level approach in the density matrix expansion. Our results show that it is possible to design suitable devices described by a Morse-like confinement pattern in the desired wavelength by changing the mentioned parameters., Colombian Agency: CODI-Universidad de Antioquia (Estrategia de Sostenibilidad de la Universidad de Antioquia); Colombian Agency: CODI-Universidad de Antioquia (project "Efectos de capas delta dopadas en pozos cuanticos como fotodetectores en el infrarrojo"); Colombian Agency: Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD-exclusive dedication project 2018-2019); Scientific Research Project Fund of Cumhuriyet University (CUBAP) [F-557], This research was partially supported by Colombian Agencies: CODI-Universidad de Antioquia (Estrategia de Sostenibilidad de la Universidad de Antioquia and project "Efectos de capas delta dopadas en pozos cuanticos como fotodetectores en el infrarrojo") and Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD-exclusive dedication project 2018-2019). This work used resources of the Centro Nacional de Processamento de Alto Desempenho em Sao Paulo (CENAPAD-SP). The authors are grateful to The Scientific Research Project Fund of Cumhuriyet University (CUBAP) under the project number F-557.

WOS: 000443747000006, PubMed ID: 30185886, The electronic states in GaAs-AlxGa1-xAs elliptically-shaped quantum rings are theoretically investigated through the numerical solution of the effective mass band equation via the finite element method. The results are obtained for different sizes and geometries, including the possibility of a number of hill-shaped deformations that play the role of either connected or isolated quantum dots (hills), depending on the configuration chosen. The quantum ring transversal section is assumed to exhibit three different geometrical symmetries - squared, triangular and parabolic. The behavior of the allowed confined states as functions of the cross-section shape, the ring dimensions, and the number of hills-like structures are discussed in detail. The effective energy bandgap (photoluminescence peak with electron-hole correlation) is reported as well, as a function of the Al molar fraction., Universidad EIA; CODI-Universidad de Antioquia; Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia; Colombian Agency \emph{El Patrimonio Autonomo Fondo Nacional de Financiamiento para la Ciencia, la Tecnologia y la Innovacion, Francisco Jose de Caldas-COLCIENCIAS}; Mexican Conacyt [206772]; Universidad de Antioquia, J. A. Vinasco acknowledges the support and fruitful cooperation with Prof. Dr. A. Radu during his doctoral stay at the Department of Physics, "Politehnica" University of Bucharest, where part of this work was done. This research was partially supported by Colombian Agencies: Universidad EIA, CODI-Universidad de Antioquia (Estrategia de Sostenibilidad de la Universidad de Antioquia and projects "Efectos de capas delta dopadas en pozos cuanticos como fotodetectores en el infrarrojo" and "Efectos Opticos intersubbanda, no lineales de segundo orden y dispersion Raman, en sistemas asimetricos de pozos cuanticos acoplados"), and Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD-exclusive dedication project 2017-2018 and ALM-exclusive dedication project 2018-2019). This work used resources of the Centro Nacional de Processamento de Alto Desempenho em Sao Paulo (CENAPAD-SP). J. A. Vinasco acknowledges the doctoral financial support from the Colombian Agency \emph{El Patrimonio Autonomo Fondo Nacional de Financiamiento para la Ciencia, la Tecnologia y la Innovacion, Francisco Jose de Caldas-COLCIENCIAS}. M. E. Mora-Ramos acknowledges support from Mexican Conacyt through Grant 206772. The authors are grateful to the Universidad EIA and Universidad de Antioquia for financial support through the EIA-UdeA-UdeM-project "Generacion de segundo armonico, rectificacion Optica y dispersion Raman entre estados electronicos en pozos cuanticos acoplados".

Background A multicenter antiphospholipid antibody (aPL) clinical database was created in 2016 with the pariticipation of six rheumatology centres around the country. The purpose has been to better define aPL-related clinical manifestations and management strategies; and also to establish a resource for future clinical studies. Objectives In this first analysis, we compared the clinical and laboratory features of aPL-positive patients with and without systemic lupus erythematosus (SLE). Methods The demographic, clinical, laboratory, treatment characteristics of the aPL-positive patients with/without other systemic autoimmune diseases (SAID) are recorded at enrollment according to a predefined protocol. The inclusion criteria are positive aPL (lupus anticoagulant test [LA], anticardiolipin antibody [aCL], and/or anti β2-glycoprotein-I antibody [aβ2GPI]) based on the Updated Sapporo Antiphospholipid Syndrome (APS) Classification Criteria at least twice within one year prior to enrolment.1,2 For the purpose of this analysis, we only included aPL-positive patients without other autoimmune diseases (primary aPL/APS) and aPL-positive SLE patients (SLE aPL/APS). Results As of January 2018, 105 aPL-positive patients were recruited (mean age: 42.6±10.1 [min-max: 19–70]; 83 [79%] female; and 67 [64%] with another SAID). Ten patients were excluded from the analysis due to their SAID history other than SLE. Of the remaining 95 patients, 38 (40%) had primary aPL/APS; 57 (60%) fulfilled the ACR SLE Classification Criteria; 42 (44%) had thrombotic APS (TAPS) (8 arterial, 24 venous, and 8 both); 21 (22%) had obstetric APS (OAPS); 22 (23%) had both TAPS and OAPS (7 arterial, 14 venous, and 1 both); and 10 (11%) had no TAPS/OAPS. Fifty percent of the patients had history of at least one non-criteria aPL-manifestation. Demographics, clinical and laboratory manifestations, and medications were similar between primary aPL/APS and SLE aPL/APS patients except increased frequency of autoimmune hemolytic anaemia, aCL IgG, and hydroxychloroquine use in SLE aPL/APS patients (table 1). Conclusions The analysis of our multicenter aPL database demonstrates that the frequencies of thrombosis and pregnancy morbidity are similar between aPL-positive patients with or without SLE. Half of the patients in both groups had history of at least one “non-criteria” aPL-manifestation; only autoimmune hemolytic anaemia was more frequent in aPL-positive patients with SLE. References [1] Schreiber K, Sciascia S, de Groot PG, Devreese K, Jacobsen S, Ruiz-Irastorza G, et al. Antiphospholipid syndrome. Nat Rev Dis Primers2018;4:17103. [2] Gomez-Puerta JA, Cervera R. Diagnosis and classification of the antiphospholipid syndrome. J Autoimmun2014;48–49:20–5. Disclosure of Interest None declared

WOS: 000432750900015, The third-harmonic generation (THG) coefficient for a laser-driven quantum dot with an on-center Gaussian impurity under static magnetic field is theoretically investigated. Laser field effect is treated within the high-frequency Floquet approach and the analytical expression of the THG coefficient is deduced from the compact density-matrix approach. The numerical results demonstrate that the application of intense laser field causes substantial changes on the behavior of THG. In addition the position and magnitude of the resonant peak of THG coefficient is significantly affected by the magnetic field, quantum dot size and the characteristic parameters of the impurity potential.

WOS: 000425197400031, For a quantum well which has the Tietz-Hua potential, the ground and some excited donor impurity binding energies and the total absorption coefficients, including linear and third order nonlinear terms for the transitions between the related impurity states with respect to the structure parameters and the impurity position as well as the electric field strength are investigated. The binding energies were obtained using the effective-mass approximation within a variational scheme and the optical transitions between any two impurity states were calculated by using the density matrix formalism and the perturbation expansion method. Our results show that the effects of the electric field and the structure parameters on the optical transitions are more pronounced. So we can adjust the red or blue shift in the peak position of the absorption coefficient by changing the strength of the electric field as well as the structure parameters. (C) 2017 Elsevier B.V. All rights reserved., Scientific Research Project Fund of Cumhuriyet University (CUBAP) [F-516]; Scientific Research Project Fund of Cumhuriyet University (CUBAP) [F-516], The authors are grateful to The Scientific Research Project Fund of Cumhuriyet University (CUBAP) under the project number F-516.

WOS: 000358320100004, In the present work, the effects of the intense laser field on total optical absorption coefficient (the linear and third-order nonlinear) and total refractive index change (the linear and third-order nonlinear) for transitions between different intersubbands in the Ga1-xAlxAs/GaAs cylindrical quantum clot under external electric field are investigated. The calculations were performed within the compact density-matrix formalism with the use of the effective mass approximation. The obtained results show that both total absorption coefficient and refractive index change are sensitive to the electric and intense laser fields. By changing the intensities of the electric and laser fields, we can obtain the blue or red shift, without the need for the growth of many different samples. (C) 2015 Elsevier B.V. All rights reserved

The combined effects of electric and magnetic fields on the optical absorption coefficients and refractive index changes related to the intersubband transitions within the conduction band of asymmetric GaAs / Ga 1 - x Al x As double inverse parabolic quantum wells are studied using the effective-mass approximation and the compact density-matrix approach. The results are presented as a function of the incident photon energy for the different values of the electromagnetic fields and the structure parameters such as quantum well width and the Al concentration at the well center. It is found that the optical absorption coefficients and the refractive index changes are strongly affected not only by the magnitudes of the electric and magnetic fields but also by the structure parameters of the system.