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The optical properties for nano-structured semiconductor systems are of great importance nowadays, due to its possible implementation for the design of efficient optoelectronic devices. It is also well known that external fields can modify the electronic structure, and induce changes the optical properties as well. In particular the asymmetric double quantum well structures are of paramount importance because its wide range on possible configurations and also because are experimentally feasible and well controlled, particularly AlxGa1-xAs/GaAs heterostructures. In this work we report a systematic study on second harmonic generation (SHG) for an asymmetric AlxGa1-xAs/GaAs double quantum well as a function of non-resonant intense laser field and in-plane magnetic field effect. We analyze the energy level behavior as well as the dipole matrix elements as a function of the above mentioned factors that are important for the SHG. We report a particular configuration that optimize the SHG peak, with and without intense laser field effect, as well as magnetic fields, that also tune the SHG.

In this present study, we have investigated theoretically the effect of structure parameters ( η and κ ) and high-frequency intense laser field (ILF) on the linear and nonlinear optical properties of a GaAs quantum well (QW) with new type of hyperbolic confinement potential. Within the framework of the effective-mass and parabolic band approximations, we have computed the confined subband energy levels and their corresponding densities of probability by using the diagonalization method. Besides, we evaluated the total optical absorption coefficients (TOACs) and total refractive index changes (TRICs). The obtained numerical findings show that an increase of the η ( κ ) structure parameter causes an increase (decrease) in amplitude in TOACs and a blue (red) shift of the resonance energy spectrum. In addition, with the increase of the ILF, the resonance energy spectrum shifts to blue, while the amplitude of TOACs (TRICs) increased (decreased). We think that the obtained these results can be useful in the design of new device’s generation employed in optoelectronic domain.

We are presenting a theoretical investigation on the effects of applied electric, magnetic, and non-resonant intense laser field on the coefficients of intersubband linear, third-order nonlinear, and total optical absorption and of relative refractive index change in GaAs/GaAlAs quantum wells with exponentially confining potential. It also includes the study of the impact of adjustable potential parameters. The energy states of conduction band electrons in the structure are calculated by using the effective mass and envelope function approximations. With regard to the optical response, it is found that with the strengthening of magnetic field, the resonant peak positions shift to lower energies and their magnitudes decrease. Increasing in the values of adjustable potential parameters as well as of the static electric and laser intensities causes the peak positions to shift toward higher energies and their magnitudes to augment. These results show that the optical properties of the system can be adjusted according to the purpose, by changing the magnitude of applied external fields and structure parameters.

The paper presents the nonlinear optical rectification, second and third harmonic generation properties of a quantum well-formed within AlGaAs/GaAs heterostructures under the Razavy potential function. The effects of well parameters as well as applied external fields such as electric, magnetic, and non-resonant intense laser on these parameters are examined. The energies of sub-bands and dipole moment matrix elements related to wave function probabilities are obtained by solving the Schrödinger equation within effective mass and parabolic band approximations. Optical coefficients are calculated in the framework of the density matrix approach. The findings point out that the potential distribution parameters strongly affect the magnitudes as well as the locations of nonlinear optical rectification, second and third harmonic generation peaks on the corresponding incident photon energies. Besides the influences of potential parameters, subjecting the system to intense laser field leads noticeable changes on the NOR, SHG, and THG coefficients. However the changes on these properties are quite slight when the system subjected to the external electric or magnetic field. Razavy potential parameters are more effective in controlling the optical properties in comparison to the electric and magnetic field perturbations.

Linear, third-order, total optical absorption and relative refractive index change coefficients are investigated for an ntype δ-doped GaAs/AlxGa1−xAs quadruple quantum well with electric, magnetic as well as laser fields as external probes. The Hamiltonian operator of the quaternary δ-dopedwell iswritten with the inclusion of laser dressed potential term and electric, magnetic field energy operators, in order to obtain the electronic spectrum. Optical properties are calculated by obtained electronic states within the framework of compact density matrix approach. The results show that, in the presence of external electric, magnetic and intense laser fields, the evaluated optical coefficients exhibit similar shifting characteristic with different peak magnitude variations. These findings in the optical properties of quadruple δ-doped quantum wells in the presence of external fields may provide guidance to the practical studies.

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.

WOS: 000458815300063, PubMed ID: 30764987, In the present work, the effect of non-resonant intense laser field on the nonlinear optical rectification and second and third harmonic generation of n-type double delta-doped GaAs quantum well is studied in detail. The energy eigenvalues and eigenfunctions of this structure are calculated within the framework of effective mass and envelope function approximations. Analytic formulas for the coefficients of nonlinear optical rectification and second and third harmonic generation are obtained using the compact-density matrix approach (CDMA) and iterative method. Based on this model, our obtained numerical results are reported as a function of incident photon energy for several values of non-resonant intense laser field. The results show that the coefficients of nonlinear optical rectification and second and third harmonic generation are strongly affected by the non-resonant intense laser field.

In this work, we present a theoretical simulation of the impact of applied external fields and structural parameters on the total (linear plus nonlinear) optical absorption coefficient (TOAC) and total refractive relative index change coefficient (TRICs) in a heterostructure based on symmetric and nonsymmetric triple Gaussian quantum wells. The asymmetricity of the heterostructure was introduced by adjusting the depths of central and left potential wells. At first, we have calculated the wavefunctions and the subband energy levels for the lowest bounded states confined within the structure by solving the Schrödinger equation within the framework of the effective mass approximation under the impact of electric and magnetic fields. Throughout our study, the matrix elements and occupation ratio factor, which control the evolution of TOACs and TRICs, were evaluated and commented. The obtained results show that an increase of the intensity of electric and magnetic field produces a red shift in the TOACs and TRICs. Furthermore, we find that by increasing the depth of the left-hand quantum well (VLW), the modification of the confining potential profile, which becomes asymmetric, leads to a blue-shift behavior of the TOACs and TRICs at first and then a red-shift. We believe that the present study opens the way to the design of new optoelectronic devices operating in large spectral emission.

In this study, the effects of hydrostatic pressure, temperature, and high-frequency intense laser field on the nonlinear optical properties of an asymmetric GaAs/AlGaAs double quantum well was theoretically investigated. For this, firstly, the energy eigenvalues and eigenfunctions of the system have been obtained using the effective-mass and parabolic band approximation. Later, the nonlinear optical properties of the structure are calculated using the compact-density matrix approach. The obtained numerical results show that when the magnitude of the intense laser field applied to the structure is increased, the amplitudes of both the total optical absorption coefficients (TOACs) and the relative refractive index changes (RRICs) peaks increase and shift towards higher energies. In addition, it was also observed that the increase in temperature had a similar effect on the TOACs and RRICs with the intense laser field, whereas the increase in hydrostatic pressure has an opposite effect.

A theoretical investigation of intraband nonlinear optical properties of a GaAs quantum well with inversely quadratic Hellman potential have been performed. It considers the presence of external electric and magnetic fields. In addition to this, the effects of the adjustable physical parameters ( $$\eta $$ and $$V_0$$ ) of the system on the optical properties of this structure were also investigated. For these numerical calculations, firstly, the conduction subband energy levels and the corresponding wave functions are obtained by solving the Schrodinger equation using the diagonalization method within the framework of effective mass and parabolic band approximations. Based on this information, results of numerical calculations for the linear, third-order nonlinear, and total optical absorption and relative refractive index change coefficients are presented. The obtained numerical results show the increase of the resonance peaks amplitudes with applied external electric and magnetic fields, as well as the shifting of their position the towards higher energies. It was also observed that the variations in $$\eta $$ and $$V_0$$ have important effects on the magnitude and position of the resonance peaks. We believe that these results can be helpful in the design and practice of the optoelectronic devices used in the terahertz electromagnetic spectrum.

In this present work, for different impurity position and ionized doping concentrations, we have theoretically investigated the linear, third-order nonlinear, and total optical absorption coefficients corresponding to the $$(1\rightarrow 2)$$ intersubband transitions between the ground and first-excited conduction band states in a single $$\delta $$ -doped GaAs well, with and without the presence of a donor impurity. Impurity binding energies were calculated using the effective-mass and parabolic band approximations within a variational scheme. The linear, third-order nonlinear, and total optical absorption coefficients for the intersubband transitions are calculated within the compact density matrix approach. The obtained results show that adding an impurity positioned at the symmetry center of the well, as well as the increase in the ionized donor concentrations, shifts the total optical absorption coefficients to higher photon energies. However, the off-center positions of impurities together with the varying ionized donor concentrations lead to blue or red shifts in relation to the values of binding energies. The results in this study may be useful for the design and applications of the devices based on the $$\delta $$ -doped structures.

A theoretical investigation on the conduction electron states in a triple inverse parabolic AlGaAs/GaAs quantum well, designed in the spirit of the active region for a quantum cascade laser, is performed. The study includes the influence of externally applied static electric and magnetic fields. The energy values and corresponding eigenfunctions are determined with the use of the effective mass approximation within the parabolic band description. The information on the allowed states is, then, used to evaluate some coefficients that represent the intraband nonlinear optical response of the structure. Numerical results are presented for the optical absorption and relative refractive index change coefficients as well as for those of nonlinear optical rectification and second harmonic generation. It is discussed that, in general, the amplitude and position of resonant peaks in the calculated quantities can be noticeably affected by the variation in the strength of the applied probe fields. Accordingly, the features of the investigated properties could suitably determine the application of this kind of structures for device proposals, as long as they can affect lasing regime in them.

In this study, the effects of the external static electric field and high-frequency intense laser field (ILF) on the nonlinear optical properties, such as the relative refractive index changes (RRICs) and the total optical absorption coefficients (TOACs), of a cylindrical quantum dot (CQD) with axial Morse potential are theoretically investigated in detail. The effect of the structure parameters on the optical properties of the system are analysed, optimizing the CQD in terms of RRICs and TOACs. Solutions of the wave equation of the system are carried out by using the effective-mass and parabolic band approximation. The optical properties of the system are probed by using the compact-density-matrix approach. The numerical results show that the optical spectrum of the system shifts to red or blue. Furthermore, these results clearly demonstrated that the optical properties of the system depend on closely both the applied external fields and the structure parameters. As a result, these behaviors in the optical properties of the structure give us a new degree of freedom in the regions of interest for optoelectronic device applications.

The effects of in-growth applied electric fields and in-plane (x-oriented) magnetic fields on the nonlinear optical rectification (NOR), second harmonic generation (SHG) and third harmonic generation (THG) of n-type asymmetric double $$\delta$$ -doped GaAs quantum well are theoretically investigated. One-dimensional Schrodinger equation is solved by considering effective mass and parabolic band approximations to obtain subband energy levels and their related wave functions. The variations in the NOR, SHG and THG coefficients are determined by using the iterative solutions of the compact density matrix approach. Obtained results indicate that the applied electric field leads to optical red-shift on NOR, SHG and THG coefficients while the magnetic field causes optical blue-shift on that coefficients. Hence we can conclude that applied electromagnetic fields can be used to tune optical properties of devices working within the region of infrared electromagnetic spectrum.

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.

A numerical investigation on the nonlinear optical rectification, second and third harmonic generation coefficients in asymmetric double n-type $$\delta $$ -doped GaAs quantum well is performed in order to identify the influence of non-resonant intense laser radiation, doping concentration and the change in well widths. The energy eigenvalues and the corresponding eigenfunctions are determined by using effective-mass and parabolic band approximations. The working analytical expressions for the optical coefficients are derived from the iterative solving of compact-density matrix description of dielectric susceptibility. The obtained results reveal that the position and amplitude of the nonlinear optical rectification, second and third harmonic generation coefficients can be altered by modifying the external field as well as the compositional and geometrical setups.

In the present study, the effect of the depth of the confinement potential on the nonlinear optical of a GaAs quantum well with short-range bottomless exponential potential is studied in detail. The energy eigenvalues and eigenfunctions of this structure are calculated within the framework of effective mass and envelope function approximations. Analytic formulas for the linear, third-order nonlinear and total absorption coefficients and relative refractive index changes are obtained using the compact-density matrix approach (CDMA) and iterative method. Based on this model, our obtained numerical results are reported as a function of incident photon energy for several values of the depth of the confinement potential. The results show that the linear, third order nonlinear, and total absorption coefficients and relative refractive index changes are strongly affected by the depth of the confinement potential.

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: 000436446900004, In this work, the effects of the structure parameters, such as the central barrier thickness and the aluminium concentrations x, on the linear and nonlinear intersubband optical absorption coefficients and refractive index changes of the asymmetric double-graded quantum wells (ADGQWs) under the presence of an external static electric field are studied theoretically. The nonlinear optical properties of the ADGQWs are obtained using the compact-density matrix approach and iterative method. The numerical results obtained from the present work show that the external static electric field and the structure parameters play an important role in the optical properties of ADGQWs. Depending on the asymmetric nature of the confinement potential, in an electric field of

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.

In this present work, the effect of applied external fields and well width on the optical absorption and refractive index change coefficient of a GaAs quantum well with Razavy confinement potential is theoretically presented. For this, firstly, the confined subband energy levels of the structure and the envelope wave functions corresponding to these states have been computed using the diagonalization method within the framework of effective mass and parabolic band approximation. Then, by using this information, the coefficients of total – linear plus nonlinear – intersubband optical absorption (TOAC) and relative refractive index changes (RRIC) of the structure are evaluated. The obtained numerical results show that the increase in the magnitude of the applied external fields creates a blue shift in TOAC and RRIC. Also, contrarily to the applied external fields, an increment of the quantum well width have induced a red shift in the TOAC and RRIC. We discuss in detail the variation of the diagonal matrix elements and the energy difference (E2–E1) which are responsible for the change of amplitudes of the calculated coefficients. We believe that the obtained numerical results can be useful in the design and application of the next generation devices used in the optoelectronics field.

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.

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.

WOS: 000397696300010, In this study, the effects of electric and magnetic fields on the optical rectification and second and third harmonic generation in asymmetric double quantum well under the intense non-resonant laser field is theoretically investigated. We calculate the optical rectification and second and third harmonic generation within the compact density -matrix approach. The theoretical findings show that the influence of electric, magnetic, and intense laser fields leads to significant changes in the coefficients of nonlinear optical rectification, second and third harmonic generation. (C) 2017 Elsevier B.V. All rights reserved.

WOS: 000461957300001, A theoretical study of the effects of non-resonant intense laser field on the donor impurity binding energy in a cylindrical quantum dot with delta-doped axial potential is performed in the framework of the effective mass approximation. The obtained results indicate that, 2D impurity concentration and intense laser field intensity have a significant effect on the impurity binding energy and energy levels of electrons in the cylindrical quantum dots with delta-type axial potential.

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.

In this work, the electronic structure and the inter-subband absorption coefficient (IAC) are theoretically studied for symmetric double n-type δ-doped GaAs quantum well considering the donor impurity atom effect. The electron states are determined by a diagonalization procedure, working within the effective mass and parabolic band approximations, and the effect of donor center is treated via the variational method. Meanwhile, linear and nonlinear contributions for the inter-subband absorption coefficient were evaluated from expressions usually derived within the perturbative solution of the Von Neumann equation for density matrix. We report the impurity binding energy by considering a donor atom located at the center of the system (at zi = 0). We found that the reported physical properties become more sensitive to the inter-well separation distance Lw than to the δ-doping density, N2d. In the former case the total optical absorption coefficient undergoes an important red-shift as well as a significant decrease in its magnitude. When N2d values increase, the binding energy exhibits a contrary effect, and the total optical absorption coefficient exhibits an small blue-shift with no significant changes in its magnitude. The presence of the donor impurity atom in the system represents one factor that can modify the location of inter-subband absorption coefficient, by inducing a blue-shift of the optical response. The resonant peak energies are within the range of several terahertz, showing potential device applications within this range of the electromagnetic spectrum.

Simultaneous effects of electric, magnetic, and non-resonant intense laser field on the nonlinear optical properties of a GaAs quantum well with an anharmonic confinement potential profile are theoretically investigated. Energy eigenvalues and eigenfunctions of the system are determined using the diagonalization method within the framework of the effective mass and parabolic band approximation. Nonlinear optical properties associated to the inter and intra band transitions are evaluated. Our numerical results for the intra-band response show that the resonance peak positions of the total optical absorption coefficients and relative refractive index changes shift towards higher energy levels (blueshift) by increasing the strength of the applied external electric, magnetic, and non-resonant intense laser field. The analysis of inter-band (electron-heavy hole) transitions reveals that the optical coefficients has a pronounced redshift induced by the electric field while a blueshift is caused by the magnetic and laser signals. It is seen that the nonlinear optical properties of such structures can be adjusted according to the purpose by changing the external perturbations and could be used in new optoelectronic device designs.

In this work, we have investigated theoretically the impact of intense laser, electric and magnetic fields on the linear and nonlinear optical properties of a quantum well heterostructure containing triple parabolic barriers (GaAs/AlGaAs). Within the framework of the effective-mass and parabolic band approximations, we have computed the confined lowest energy levels and their corresponding densities of probability, through the use of a finite difference technique to solve the corresponding differential equation. Besides, we evaluate the total optical absorption (TOACs) and relative refractive index change (RRICs) coefficients. The obtained findings show that an increase of the intensity of the intense laser field produces a blue shift at first and then a red shift of the TOACs and RRICs. A specific value of the laser field separating the two kinds of signal displacements is outlined. Contrarily to the intense laser field, an increment of the external static electric and magnetic fields induces only a blue shift in the variation of the TOACs and RRICs. In addition, we have discussed in detail the variation of diagonal and non-diagonal matrix elements which are responsible on the variation of the amplitudes of the TOACs and RRICs. We think that the obtained results can be useful in the design of new device's generation employed in optoelectronic domain.

The asymmetric potential profiles are of great interest from the nonlinear optical properties point of view for semiconductor devices. The reason for this statement is because the existing theories on nonlinear optical properties obviously depends on the dipole matrix element for the involved transitions and an complete characterization for asymmetric potential profiles enables to the semiconductor device designers to have possible ranges of implementation and because the dipole matrix elements strongly depends on the asymmetry of the potential profile. Once the potential profile is well defined, with the desired range on operation, the external factors play also an important role on the optical properties tuning. In particular, in this paper we reported the absorption coefficient and the relative refractive index changes for semi-infinite inverse Gaussian-like profile for an AlxGa1−xAs/GaAs quantum well when is subjected to a z-directed electric field, to an in-plane x-directed magnetic field and finally to a non-resonant intense laser field effect, being the Al concentration the parameter that allows to shape the potential profile. In general, we conclude that the external factor are an efficient way to tune the optical properties that are in the range of the THz spectrum, at least for the intersubband transitions reported here.

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: 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.

We study the confined states of a molecule formed by two laterally coupled quantum dots. The static electric field and incident plane wave laser field are considered with different polarization. The respective Shrodinger equation is obtained in the framework of the high-frequency limit of Floquet theory. It is shown that the electric field has a qualitative impact on the spatial symmetry of electronic states. An in-depth study of electric and laser field combined effects show a strong correlation between them. Additionally, we show that the linear, nonlinear and total optical absorption coefficients and relative refractive index of the considered structure can be effectively tuned by changing electric field strength and intense laser field parameter. Our results indicate the possibility of controlling the optical response of double quantum dots molecule for future applications in nanostructure-based quantum information science.

In the present work, some optical properties related to intersubband transitions in finite depth asymmetric hyperbolic-type quantum wells are theoretically investigated. The use of a hyperbolic potential configuration would account for the actual – non abrupt – confinement potential in the heterostructure, in the case of modulated growing or when compositional diffusion across the interfaces turns out to be relevant. In the investigation, the presence of externally applied electromagnetic fields is considered. Electron conduction band states are determined within the parabolic band an effective mass approximation. With the electronic structure information at hand, it is possible to evaluate the linear and third-order nonlinear light absorption and relative refractive index change coefficients, from expression arising in the framework of the compact density matrix approach. According to the theoretical outcome, it is found that: (i) There is a significant influence of the structural configuration on the magnitude and resonant peak position of the total optical coefficients. (ii) Under the effect of increasing external electric and magnetic fields, the peak energy positions are shifted towards higher values, whereas their amplitude decrease for the optical absorption case, and that of the refractive index relative variation is reduced. From these results it can be concluded that both the modification of the confinement profile and the presence of electric and/or magnetic fields are suitable tool to control the optical response of asymmetric hyperbolic-type semiconductor quantum wells. © 2020 Elsevier B.V.

We present a theoretical study on the effects of intense laser field (ILF) and static electric field on the linear and nonlinear optical properties of a cylindrical quantum dot with Rosen-Morse axial potential under the framework of effective mass and parabolic band approximations. This study also takes into account the effects of the structure parameters (η, V 1, and R). The analytical expressions of the linear, third-order nonlinear and total optical absorption coefficients (TOACs) and the relative refractive index changes (RRICs) are obtained by using the compact-density-matrix approach. The results of numerical calculations show that the resonant peak position of the TOACs and RRICs shifts towards lower energies and the magnitude of the peak increases with the effect of the static electric field and ILF. In addition, it is observed that while the resonant energies of the TOACs and RRICs of system shift towards the higher (lower) energies with the enhancement of η, V 1, they decrease with the augmentation of R. Thus, the findings of this study show that the optical properties of the structure can be adjusted by changing the magnitude of structure parameters and applied external fields. © 2020 Chinese Physical Society and IOP Publishing Ltd.

WOS: 000463848000012, In the present study, the effects of varying doping concentration and applied electric field on the intersubband-related optical absorption and relative refractive index change coefficients in modulation-doped GaAs/AlxGa1-x As double quantum wells are theoretically investigated. The allowed energy levels and the corresponding wave-functions are calculated by solving the Schrodinger and Poisson equations self-consistently within the framework of the effective-mass and parabolic band approximations. The optical coefficients are evaluated using the compact density matrix formalism within an iterative procedure. The numerical results are presented for two different doping concentration and several values of the electric field. They show that both the peak position and the magnitude of the calculated total optical absorption coefficients and refractive index changes are significantly affected by the applied electric field and the doping concentration. The treatment is suitable to consider the general problem with different wells and barrier sizes, although the barrier width should preferably be small enough as to allow for an effective inter-well coupling., Universidad EIA; Universidad de Antioquia through the EIA-UdeA-UdeM-project "Generacion de segundo armonico, rectificacion Optica y dispersion Raman entre estados electronicos en pozos cuanticos acoplados", CAD is grateful to the 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). RLR and CAD 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".

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.

In the present study, we present numerical results for the influence of non-resonant intense THz laser radiation as well as the structure parameters, such as well width and central doping concentrations, on the total optical absorption coefficients (TOACs) and relative refractive index changes (RRICs) in n-type asymmetric triple δ-doped G a A s quantum well (QW) by using the compact-density-matrix formalism via iterative method. In order to obtain these numerical results, we have first obtained the subband energy spectrum and the electronic wave functions of the structure by using the effective-mass and parabolic band approximation. We have then calculated the nonlinear optical (NLO) properties of the system, by employing these energy eigenvalues and eigenfunctions. The numerical results for these calculations show that; (i) the magnitude of the resonant peak of TOACs decreases and the peak position shifts towards the lower energies when the central doping concentration and the well width are increased; (ii) due to the intense laser field effect, the magnitude of the TOACs resonant peak initially increases and its position shifts towards higher energies and then it decreases, shifting towards lower energies; (iii) by increasing the central doping concentration (well width), the magnitude of the resonant peak of RRICs increases (decreases), and the resonant peak position shifts towards the lower energies; and finally (iv) because of the increase in the intensity of the laser field applied to the structure, the magnitude of the resonant peak of RRICs increases, and the resonant peak position initially shifts towards the higher energies and then shifting towards the lower energies.

WOS: 000470938600035, In this study, for the first time, the influences of a monochromatic linearly polarized laser field on the total refractive index changes (TRICs) and the total absorption coefficients (TACs) of quantum well (QW) with the Rosen-Morse potential confinement by constituting GaAs/GaAlAs heterostructure are considered. Time-dependent in the Schrodinger equation is modified through the Kramers-Henneberger (KH) transformation and the dipole approximation, and then the laser-dressed counterpart of well potential is generated by using the Ehlotzky approximation. The bound state energy values and the wave functions of the Rosen-Morse quantum well (RMQW) under the influence of the intense laser field (ILF) are obtained by using the diagonalization method in the framework of the effective mass approach and the parabolic band approximation. The effects of structure parameters on TRICs and TACs of RMQW are also explained in detail, as well as the ILF's ones. In addition to these, the alternativeness to each other of the structure parameters and the ILF on the optical specifications is also discussed. The results of the present work are necessary and crucial in optimization of the optical specifications of RMQW to be fabricated for devices applications.

We present a theoretical investigation about the the influence of external electric, magnetic and non-resonant intense laser fields on intersubband-related second harmonics generation (SHG) and the nonlinear optical rectification (NOR) coefficients in n-type asymmetric triple ?-doped quantum wells (QWs). A particular design of asymmetric triple ?-doped QW with L w = 200 A width and, respectively, in the left side, central and right side, and doping concentrations is taken into account. For QWs under the combined effect of the external electric, magnetic and laser fields, the time-dependent wave equation is modified by using Kramers-Henneberger transformation and the dipole approximation. The subband energy spectra and the electronic wave functions are obtained by solving numerically the wave equation. The originality of this work can be presented as; (i) The results explain NOR and SHG characteristics of triple QW depending on external field effects in detail. The effects of the electric, magnetic and laser field on transition energies and NOR, SHG characteristics are presented detail. (ii) In addition to, the alternativeness to each other of the external fields is discussed by probing the features of SHG and NOR under the strong and weak regimes of external fields. (iii) These nonlinear optical responses to the external fields are compared, researching the optimum cases for these optical specifications. (iv) The control of SHG through the external fields in triple ?-doped QWs reveals to be easier and more precise. © 2020 IOP Publishing Ltd.

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.