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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.

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: 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: 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: 000410633400033, In this research, we present the effects of high-frequency intense laser field on the third-harmonic generation associated with intersubband transitions in a two-dimensional quantum pseudodot system subjected to an uniform external magnetic field. Non-resonant monochromatic laser radiation with circular polarization is considered within the framework of high-frequency Floquet approach. On the basis of the compact-density matrix approach and an iterative method, the third-harmonic generation coefficient is calculated. The results presented for a GaAs quantum dot show that: (i) the position and magnitude of the resonant peak of third-harmonic generation depend strongly on magnetic field, the chemical potential and zero-point of pseudoharmonic potential; (ii) the strength of intense laser field modifies the confinement potential which results in considerable changes in the nonlinear optical response of the system.

WOS: 000362603100020, In this work, we studied the effects of in-plane magnetic field and Rashba spin-orbit interaction on the intersubband optical absorption coefficients and changes in refractive index for transitions between the first two lower-lying electronic levels of quantum wire represented by a parabolic confining potential. 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 quantum wire radius, strength and orientation of magnetic field, strength of Rashba spin-orbit interaction and photon energies. Numerical results reveal that the optical absorption coefficients and refractive index changes are strongly affected and thus can be controlled by these parameters. (C) 2015 Elsevier Ltd. All rights reserved., Scientific and Technological Research Council of Turkey [TUBITAK BIDEB 2211], One of the authors (B. Gisi) would like to thank the Scientific and Technological Research Council of Turkey (TUBITAK BIDEB 2211) for partial financial support.

WOS: 000359873200042, We investigate the effects of Rashba spin-orbit interaction on the electronic energy dispersion and zero-temperature ballistic conductance of double quantum wire under the influence,of perpendicular magnetic field. The wire system is represented by a symmetric, double quartic-well confinement potential. Numerical results reveal that competing effects between spin-orbit interaction and magnetic field modify strongly the energy subband structure and introduce anticrossings between subbands. Moreover, it is found that the conductance character of a quasi-one-dimensional ballistic conductor, which is closely related to the energy-dispersion spectrum, is very sensitive to the shape of potential profile, magnetic field and Rashba spin-orbit coupling. (C) 2015 Elsevier Ltd. All rights reserved., Scientific and Technological Research Council of Turkey [TUBITAK BIDEB 2211], One of the authors (Y. Karaaslan) would like to thank the Scientific and Technological Research Council of Turkey (TUBITAK BIDEB 2211) for partial financial support. 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 Yenal Karaaslan.

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: 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.

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: 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.

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: 000466899200016, The effects of non-resonant intense laser fields on the intersubband-related light absorption and relative refractive index change coefficients in symmetric and asymmetric n-type double -doped GaAs quantum wells are investigated. Systems are assumed to be also under the influence of hydrostatic pressure and the change of temperature. The single band effective-mass and envelope function approximations, together with analytical expressions for the linear and third-order nonlinear optical coefficients are used as theoretical tools. According to the numerical outcome, the nonlinear optical response is significantly affected by the intense non-resonant laser radiation, as a result of the associated distortion of conduction band energy profiles. For instance, it is revealed there is a laser-induced transition of the confining potential from double-delta geometry to single-triangular-like shape. Given the additional variations associated with the application of hydrostatic pressure and temperature, all these external probes could be used to control and suitablly tune the electronic and optical properties of GaAs n-type double -doped GaAs quantum wells.

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

WOS: 000451653700009, In the present study, we theoretically reported the effects of applied external fields, such as intense laser field and electric and magnetic fields, on the optical absorption coefficient and refractive index changes in the Tietz-Hua potential quantum well by the compact density-matrix approach. For this, we first calculated the subband energy levels and their corresponding electronic wave functions of the structure by solving the one-dimensional Schrodinger equation within the framework of the effective mass and envelope wave function approximations. Our theoretical results show that the optical absorption coefficient and refractive index changes in the Tietz-Hua potential quantum well are sensitive to the applied external fields. The absorption spectra in the structure can be adjusted depending on the purpose by changing the strength of the applied external fields, and these results can be used to tune and control the electronic and optical properties of the Tietz-Hua potential quantum well., Scientific Research Project Fund of Cumhuriyet University (CUBAP) [TEKNO-019], The authors are grateful to the Scientific Research Project Fund of Cumhuriyet University (CUBAP) under the project number TEKNO-019.

WOS: 000414180500020, In this study, the effects of the electric and magnetic fields as well as structure parameter-gamma on the total absorption coefficient, including linear and third order nonlinear absorption coefficients for the optical transitions between any two subband in the Tietz-Hua quantum well have been investigated. The optical transitions were investigated by using the density matrix formalism and the perturbation expansion method. The Tietz-Hua quantum well becomes narrower (wider) when the gamma - structure parameter increases (decreases) and so the energies of the bound states will be functions of this parameter. Therefore, we can provide the red or blue shift in the peak position of the absorption coefficient by changing the strength of the electric and magnetic fields as well as the structure parameters and these results can be used to adjust and control the optical properties of the Tietz-Hua quantum well., 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: 000341554500016, The linear and nonlinear coefficients for the optical absorption and relative refractive index change associated with transitions between donor impurity states in a two-dimensional quantum dot of triangular shape under applied electric field are calculated for y-polarization of the incident light. Both the effective mass and parabolic band approximations have been considered. The results show that the application of a DC electric field strengthens the impurity-related optical absorption response, with particular relevance in the case of the nonlinear contribution to it. However, for a fixed donor atom position inside the triangular quantum dot, the calculations show that the in-plane orientation of the applied field can becomes a critical parameter that may lead to a strong quenching of the interstate light absorption. (C) 2014 Elsevier Ltd. All rights reserved., CONACYT [CB-2008-101777], MEMR thanks Mexican CONACYT for support through research Grant CB-2008-101777. CAD is grateful to the Colombian Agencies CODI-Universidad de Antioquia (Estrategia de Sostenibilidad 2013-2014 de la Universidad de Antioquia), Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD-exclusive dedication project 2013-2014), and El Patrimonio Autonomo Fondo Nacional de Financiamiento para la Ciencia, la Tecnologia y la Innovacion, Francisco Jose de Caldas. The work was developed with the help of CENAPAD-SP, Brazil.

WOS: 000328527800028, In this present study, we have theoretically investigated the effects of hydrostatic pressure and temperature on the nonlinear optical properties in a typical GaAs/Ga0.7Al0.3As parabolic quantum well under the intense laser field. The energy levels and wave functions are calculated using the effective mass approximation and optical properties are obtained using the compact density-matrix approach. The numerical results show that the confinement potential and the energy difference depend strongly on the intense laser field but weakly on the hydrostatic pressure and temperature. Additionally, it has been found that the linear and nonlinear optical properties in a GaAs/Ga0.7Al0.3As parabolic quantum well under the intense laser field can be tuned by changing the hydrostatic pressure and temperature. (C) 2013 Elsevier B.V. All rights reserved., Cumhuriyet University [F-399], This work was supported by the Scientific Research Project Found of Cumhuriyet University under the project number F-399.

WOS: 000328524900039, The electric field dependence of the linear and nonlinear intersubband optical absorption in double semi-graded quantum wells (DSGQWs) is investigated in the effective mass approximation. In our calculations, the position and the magnitude of the linear and total absorption coefficients depend on the electric field strength and barrier width. The resonant peak of total absorption coefficient can be bleached at sufficiently high incident optical intensities. The modulation of the absorption coefficients and the refractive index changes which can be suitable for good performance optical modulators and various infrared optical device applications can be easily obtained by tuning the electric field strength and barrier width. (C) 2013 Elsevier B.V. All rights reserved.

WOS: 000394635200014, In this work, within the effective mass approximation we have performed a theoretical study of electronic states, the intersubband-related optical absorption coefficient and relative refractive index change properties in the GaAs-based double delta-doped quantum well under non-resonant intense laser field. By solving the Schrodinger equation in the laser-dressed confinement potential, We calculated eigenvalues and corresponding eigenfunctions as an intense laser parameter. We concluded that the separation between ground and first excited energy levels in the double delta-doped quantum well increases in energy by the increase of the laser field intensity and this effect leads to an optical blue-shift in intersubband transitions. Therefore a significant tunability of the optical transitions in double delta-doped quantum well can be achieved by modulating the intensity of the intense laser field. (C) 2016 Elsevier B.V. All rights reserved.

WOS: 000391468200036, In this work, the effects of magnetic field, hydrostatic pressure and temperature on the linear and nonlinear optical properties in GaAs/AlxGa1-xAs symmetric double semi-V-shaped quantum well (DSVQWs) have been theoretically studied by using the compact-density matrix approach and the effective-mass approximation. Our numerical results show that the optical characteristic of these structures is strongly affected by the magnetic field, hydrostatic pressure and temperature.

WOS: 000386644500050, We have calculated the effects of electric and intense laser fields on the binding energies of the ground and some excited states of conduction electrons coupled to shallow donor impurities as well as the total optical absorption coefficient for transitions between 1s and 2p(+/-) electron-impurity states in a asymmetric parabolic GaAs/Ga1-x AlxAs quantum well. The binding energies were obtained using the effective-mass approximation within a variational scheme. Total absorption coefficient (linear and nonlinear absorption coefficient) for the transitions between any two impurity states were calculated from first- and third-order dielectric susceptibilities derived within a perturbation expansion for the density matrix formalism. Our results show that the effects of the electric field, intense laser field, and the impurity location on the binding energy of 1s-impurity state are more pronounced compared with other impurity states. If the well center is changed to be L-c0), the effective well width decreases (increases), and thus we can obtain the red or blue shift in the resonant peak position of the absorption coefficient by changing the intensities of the electric and non-resonant intense laser field as well as dimensions of the well and impurity positions. (C) 2016 Elsevier B.V. All rights reserved., Colombian Agency: Universidad de Antioquia; Colombian Agency: project: "Propiedades opticas de impurezas, excitones y moleculas en puntos cuanticos autoensamblados", Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD-exclusive dedication project); Colombian Agency: project: "On the way to development of new concept of nanostructure-based THz laser"), Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD-exclusive dedication project); Colombian Agency: El Patrimonio Autonomo Fondo Nacional de Financiamiento para la Ciencia, la Tecnologia y la Innovacion, Francisco Jose de Caldas, This research was partially supported by Colombian Agencies: 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"), Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD-exclusive dedication project 2015-2016), El Patrimonio Autonomo Fondo Nacional de Financiamiento para la Ciencia, la Tecnologia y la Innovacion, Francisco Jose de Caldas.

WOS: 000310044800010, The laser field dependence of the linear and nonlinear intersubband optical absorption in different graded quantum wells (GQWs) is investigated in the effective mass approximation. Results obtained show that the position and the magnitude of the linear and total absorption coefficients depend on the laser parameter and the shape of GQW. The resonant peak of total absorption coefficient can be bleached at sufficiently high incident optical intensities. Such a dependence of the exciting optical intensity on the external field strengths in different GQWs can be very useful for several potential device applications. It should point out that by applying the laser field we can obtain a blue shift or a red shift in the intersubband optical transitions. (C) 2012 Elsevier Ltd. All rights reserved.

WOS: 000300596000044, The effects of an intense, high-frequency laser field linearly polarized along the growth direction on the binding energy of excitons confined in a GaInNAs/GaAs quantum well is computed for different nitrogen and indium mole fractions by means of a variational technique within the effective-mass approximation. Our results show that such laser field creates an additional geometric confinement on the electronic and exciton states in the quantum well and the exciton binding energy depends on both the nitrogen and indium concentrations. (C) 2011 Elsevier B.V. All rights reserved., Scientific and Technological Research Council of Turkey (TUBITAK) [COST 109T650], This work supported by The Scientific and Technological Research Council of Turkey (TUBITAK) for a research Grant COST 109T650.

WOS: 000296002200009, In this study, both the linear intersubband transitions and the refractive index changes in coupled double quantum well (DQW) with different well shapes for different electric fields are theoretically calculated within framework of the effective mass approximation. Results obtained show that intersubband transitions and the energy levels in coupled DQW can importantly be modified and controlled by the electric field strength and direction. By considering the variation of the energy differences, it should point out that by varying electric field we can obtain a blue or red shift in the intersubband optical transitions. The modulation of the absorption coefficients and the refractive index changes which can be suitable for good performance optical modulators and various infrared optical device applications can be easy obtained by tuning applied electric field strength and direction. (C) 2011 Elsevier Ltd. All rights reserved.

WOS: 000291420700007, Within the framework of effective-mass approximation, we have calculated theoretically the effects of hydrostatic pressure and doping concentration on subband structure and optical transitions in modulation-doped GaAs/Al(x)Ga(1-x)As quantum well for different well widths. The electronic structure of modulation-doped quantum well under the hydrostatic pressure is determined by solving the Schrodinger and Poisson equations self-consistently. The results obtained show that intersubband transitions and the subband energy levels in the modulation-doped quantum well can be significantly modified and controlled by the well width, donor concentration and hydrostatic pressure. (C) 2011 Elsevier Ltd. All rights reserved.

WOS: 000289060100017, The effects of intense high-frequency laser field on photoionization cross-section and binding energy of shallow-donor impurities in GaAs/GaAlAs quantum dots are calculated using variational method with the effective-mass approximation. From these calculations, it has been concluded that the dependences of the impurity binding energy and photoionization cross-section on the intense laser field are very significant. (C) 2011 Elsevier B.V. All rights reserved.

WOS: 000282080000006, In this study, both the intersubband optical absorption coefficients and the refractive index changes as dependent on the magnetic field are calculated in square and graded quantum wells. Our results show that the position and the magnitude of the linear and total absorption coefficients and refractive index changes depend on the magnetic field strength and the shape of potential. The incident optical intensity has a great effect on the total absorption and refractive index changes. (C) 2010 Elsevier Ltd. All rights reserved.

WOS: 000259894100077, In this study, the intense laser-field dependence of intersubband absorption coefficient for 1-2 transition in GaAs/Ga1-xAlxAs DGQW under the electric field is investigated. The obtained results show that by changing the laser intensity together with the electric field and the well parameters (well and barrier widths) the desired energy range or spectral range of interest for intersubband and also interband absorption peak position may be tuned. This tunability gives a possibility for near-infrared electro-absorption modulators and quantum well infrared detectors. (C) 2008 Elsevier B.V. All rights reserved.

WOS: 000257915100057, In this work, using the effective mass approximation within variational approach, we have studied the behavior of the excitonic binding energies in a cylindrical quantum wire with a parabolic confinement under the effect of externally applied magnetic field. We have shown that the excitonic binding energy is sensitive to the magnetic field value in contrast to the other potential profiles studied in literature such as rectangular quantum wells (wires). (C) 2008 Elsevier B.V. All rights reserved.

WOS: 000235860200017, The binding energy of the donor in the triple-graded GaAs-(Ga,Al)As quantum well under the hydrostatic pressure, electric and magnetic fields are calculated by using a variational approach. The results have been obtained in the presence of hydrostatic pressure, magnetic and electric fields applied along the growth direction as a function of the impurity position without consideration of a mass mismatch or dielectric mismatch. (c) 2005 Elsevier B.V. All rights reserved.

WOS: 000232959400012, Using a variational approach, we have calculated the hydrostatic pressure and electric field effects on the donor-impurity related photoionization cross-section and impurity binding energy in GaAs/GaAlAs quantum well-wires. Both the results of impurity binding energy as a function of the impurity position and photoionization cross-section for a hydrogenic donor impurity placed at the center of the quantum well-wire as a function of the normalized photon energy in the quantum well-wire under the hydrostatic pressure and electric field which are applied to the z-direction for two different wire dimensions are presented. (c) 2005 Elsevier B.V. All rights reserved.

WOS: 000229921000007, The combined electric field and hydrostatic pressure effects on the binding energy of the donor impurity in double triangle quantum well (DTQW), double graded (DGQW) and double square (DSQW) GaAs-(Ga,Al)As quantum wells are calculated by using a variational technique within the effective-mass approximation. The results have been obtained in the presence of an electric field applied along the growth direction as a function of hydrostatic pressure, the impurity position, barrier width and the geometric shape of the double quantum wells. (c) 2005 Elsevier B.V. All rights reserved.

WOS: 000227500900002, We present a theoretical investigation of a novel staircase-like light emitter based on the GaAs/GaxAl1-xAs material system. The emission wavelength is around 12 mum. The device operation is based on the intersubband bound-to-bound transition. The energy band profile of the structure has been solved self-consistently. We have also calculated the oscillator strength. (C) 2004 Elsevier Ltd. All rights reserved.

WOS: 000360095000019, In this present work, the effects of the structure parameters such as the right-well width and the rightbarrier height on the linear, third-order nonlinear and total absorption and refractive index changes of asymmetric double semi-V-shaped quantum well are theoretically studied by using the compact-density matrix approach and iterative method. The electronic structure of this system is obtained by solving Schrodinger equation within the framework of effective mass approximation. Numerical results are presented for a typical GaAs/AlxGa1-xAs asymmetric double semi-V-shaped quantum well. The obtained results show that the right-well width and the right-barrier height have great effects on the optical characteristics of these structures. (C) 2015 Elsevier B.V. All rights reserved.

WOS: 000165323900014, The analytical solution of the Schrodinger equation for a multiple-quantum-well system subjected to an externally applied electric field in the growth direction and an externally applied tilted magnetic field are obtained and results are discussed. The dependence of the energy spectrum of the system on the external electric field as a function of the orbit centre is also discussed and the behaviour of the wavefunctions of the system is examined.

WOS: 000085453200026, The binding energy of excitons in symmetric and asymmetric coupled double GaAs/Ga1-xAlxAs quantum wells is calculated by using a variational approach. The results have been obtained in the presence of a uniform magnetic field, as a function of the potential symmetry, size of the quantum well and coupling parameter of the wells. We show that by increasing the applied magnetic field one can obtain large binding between electrons and holes which is similar to the change in the dimensions of the structure. This behaviour in the excitonic binding for different wells and barrier geometries can be used to study these systems in regions of interest, without the need for the growth of many different samples.

WOS: 000080303700008, A quasi-bound state approximation is used to obtain the electric field dependence of the eigenvalues, eigenfunctions, electron-hole overlap integrals and excitonic binding energies for coupled, graded double quantum wells (GDQWs). In GDQWs the intra- and interband transitions have a much stronger electric field dependence than those in the square quantum well structures. Also, unlike the single or double square wells the operation wavelength of GDQW devices can be tuned by changing not only the magnitude but also the polarity of the applied voltage. Thus GDQWs have potential for applications in optoelectronic devices such as tunable electro-absorption modulators and infrared photodetectors.

WOS: 000331026900014, In the present work, the effects of electric and magnetic fields on the optical absorption coefficient and refractive index changes associated with intersubband transitions in a GaAs/AlxGa1-xAs double inverse parabolic quantum well are theoretically calculated within the effective-mass approximation. The expressions for the linear and third-order nonlinear absorption coefficients and refractive index changes are those obtained by using the compact density-matrix approach and iterative method. The results are presented as functions of the incident photon energy for different values of the applied electric and magnetic fields. It is found that the optical absorption coefficient and refractive index changes are strongly affected by the applied electric and magnetic fields. (C) 2013 Elsevier Ltd. 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-exclusive dedication Project); EL PATRIMONIO AUTONOMO FONDO NACIONAL DE FINANCIAMIENTO PARA LA CIENCIA, LA TECNOLOGIA Y LA INNOVACION, FRANCISCO JOSE DE CALDAS; Mexican CONACYT [101777]; Scientific Research Project Fund of Cumhuriyet University [F-399]; Escuela de Ingenieria de Antioquia, This research was partially supported by Colombian Agencies: CODI-Universidad de Antioquia (Estrategia de Sostenibilidad 2013-2014 de la Universidad de Antioquia), Facultad de Ciencias Exactas y Naturales-Universidad de Antioquia (CAD-exclusive dedication Project 2013-2014), and by EL PATRIMONIO AUTONOMO FONDO NACIONAL DE FINANCIAMIENTO PARA LA CIENCIA, LA TECNOLOGIA Y LA INNOVACION, FRANCISCO JOSE DE CALDAS. The Escuela de Ingenieria de Antioquia co-supported EIA-UdeA project: Efectos de laser intenso sobre las propiedades opticas de nanoestrucuras semiconductoras de InGaAsN/GaAs y GaAlAs/GaAs. MEMR acknowledges support from Mexican CONACYT through Grant No. 101777. The authors are grateful to The Scientific Research Project Fund of Cumhuriyet University under the Project Number F-399. The work was done with the help of CENAPAD-SP, Brazil.

WOS: 000319490900011, In this study, the interband optical transitions and the binding energy of an exciton in a GaAs/Ga1-xAlxAs V-shaped quantum well (VQW) under the electric and magnetic fields are calculated. The calculations were performed within the effective mass approximation, using a variational method. It has been observed that the electric and magnetic fields provide an important effect on the electronic and optical properties in the VQW and the changes in the binding energy depend on the shape of the confinement potential. (C) 2013 Elsevier Ltd. All rights reserved.

WOS: 000298219200035, In this paper, the effects of hydrostatic pressure, temperature and intense laser field on the linear and non-linear optical processes in the conduction band of a square quantum well are numerically investigated in the effective mass approximation. The analytical expressions of optical properties are obtained by using the compact density-matrix approach. The numerical results are presented for typical square GaAs/AlxGa1-xAs single quantum well system. The nonlinear optical absorption and refractive index changes depending on the hydrostatic pressure and intense laser field are investigated for two different temperature values. The results show that the intense laser field, the hydrostatic pressure and the temperature have a significant effect on the optical characteristics of these structures. (C) 2011 Elsevier B.V. All rights reserved.

WOS: 000311196500084, In this study, the effects of hydrostatic pressure on the linear and nonlinear intersubband transitions and the refractive index changes in the conduction band of different quantum well shapes are theoretically calculated within framework of the effective mass approximation. Results obtained show that intersubband properties and the energy levels in different QWs can be modified and controlled by the hydrostatic pressure. The modulation of the absorption coefficients and the refractive index changes which can be suitable for good performance optical modulators and various infrared optical device applications can be easily obtained by tuning the hydrostatic pressure strength. (C) 2012 Elsevier B.V. All rights reserved.

WOS: 000279761500011, Using a variational approach, we have calculated the donor impurity related photoionization cross-section and impurity binding in GaAs/GaAlAs quantum-well wires under different temperature and hydrostatic pressure conditions. Our calculation have revealed the dependence of the photoionization cross-section and the impurity binding on temperature and hydrostatic pressure. (c) 2010 Elsevier Ltd. All rights reserved.

WOS: 000271908100003, We have studied the magnetic field effects on the diamagnetic susceptibility and binding energy of a hydrogenic impurity in a quantum well-wire by taking into account spatially dependent screening. Using the effective-mass approximation within a variational scheme, binding energy and diamagnetic susceptibility of donor are obtained as a function of the magnetic field, length of the square quantum well-wire for different impurity positions. It is shown that the magnetic field effects on diamagnetic susceptibility can be more important for donors in quantum well-wires over a large range of wire dimensions. (C) 2009 Elsevier B.V. All rights reserved.

WOS: 000272817600003, The diamagnetic susceptibility of a hydrogenic donor placed in Si, Ge and GaAs quantum wells with infinite confinement potential which have different effective mass anisotropy parameters (gamma = m(perpendicular to)L/m(parallel to)) has been investigated as a function of the well sizes. The binding energies of the donor have also been computed using a trial wave function with two parameters in the framework of the effective mass approximation. It has been observed that the diamagnetic susceptibility of the donor in the anisotropic materials converges rapidly to the bulk limit as the well size increases. (C) 2009 Elsevier Ltd. All rights reserved.

WOS: 000266427400003, A calculation of the binding energy of an exciton confined in cylindrical quantum wires of GaAs surrounded by (Ga, Al) As in the presence of a uniform magnetic field is reported as a function of wire radius, potential height and magnetic field strength, using effective mass approximation and variational approach techniques. For larger magnetic field strength and aluminium (Al) concentration values, the binding energies get larger as expected and are found to be in good agreement with previous theoretical reports. However, we also observed a shift in the binding energy maxima position to smaller wire radii with increasing magnetic field strength and Al concentration. (C) 2009 Elsevier Ltd. All rights reserved.

WOS: 000261812200011, We have described the calculation of hydrogenic impurity binding energies in cylindrical GaAs-Ga(1-x)Al(x)As quantum well wires (QWWs) with lateral parabolic confinement in the presence of an axial magnetic field. The numerical calculations of this system have been performed with the use of a variational procedure in the effective mass approximation. We observed sharp changes in binding energy for critical spatial confinement radius and B magnetic field values. (C) 2008 Elsevier Ltd. All rights reserved., CUBAP [F-196], This work was supported by CUBAP. No:F-196.

WOS: 000247315900003, The ground state binding energies of axial hydrogenic impurities in a coaxial cylindrical quantum well wire are reported as a function of the barrier height and the radius of wire in the presence of a uniform magnetic field applied parallel to the wire axis. The quantum well wire (QWW) is assumed to be an infinitely long cylinder of GaAs material surrounded by AlxGa1-xAs (for finite case and vacuum for infinite case). Binding energy calculations were performed with the use of a variational procedure in the effective mass approximation. We observed that the binding energy is sensitive to well radius only for both larger R values and small magnetic fields. We also compared the infinite and finite case binding energies and showed that increasing the Al concentration in the finite barrier case, binding energies are increased as expected. Our results are in good agreement and complementary with the previous theoretical works. (C) 2006 Elsevier Ltd. All rights reserved.

WOS: 000245484200034, We investigated the effects of the magnetic field on the density of impurity states in a GaAs/GaAlAs inverse parabolic quantum well (lPQW) for different Al concentrations at the well center. The calculations were performed within the effective mass approximation, using a variational method. We report in this paper the effects of the magnetic field, well width and the Al concentration at the well center on the density of states and the binding energies of the donor impurities. (c) 2006 Elsevier B.V. All rights reserved.