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A theoretical study on the optical properties of a quantum well with short-range bottomless exponential potential
(World Scientific Publ Co Pte Ltd, 2019) Ungan, F.; Mora-Ramos, M. E.; Sakiroglu, S.; Sari, H.; Sokmen, I.
The effects of external applied fields on the electron-related optical nonlinear properties in a short-range bottomless exponential potential quantum well are investigated. The potential profile behaves as inverse square root in the vicinity of the origin and vanishes exponentially toward infinity, supporting a finite number of bound states whose energies and wave functions are determined within the effective-mass approximation. The linear, third-order nonlinear and total optical absorption coefficients (TOACs) as well as the coefficient of relative refractive index changes (RRICs) of the system are calculated from the expressions derived in the framework of the compact density matrix approach. The results obtained after numerical calculations show that with the effect of the static electric and magnetic fields (high-frequency THz laser field), the resonant peak position of the optical response shifts toward higher (lower) energies and the magnitude of the peak increases.
Combined effects of intense laser field and applied electric field on exciton states in GaAs quantum wells: Transition from the single to double quantum well
(WILEY-V C H VERLAG GMBH, 2012) Duque, C. A.; Mora-Ramos, M. E.; Kasapoglu, E.; Sari, H.; Sokmen, I.
The effects of intense laser radiation on the exciton states in GaAs-Ga1xAlxAs quantum wells are studied with the inclusion of applied dc electric fields oriented along the growth direction of the system. The calculations are made within the effective mass and parabolic band approximations. The intense laser effects have been included along the lines of the Floquet method, modifying the confinement potential associated to the heterostructure. The results for the exciton binding energy, the energy of the exciton-related photoluminescence peak, and the carriers overlap integral are presented for several configurations of the quantum well size, the strength of the applied electric fields, and the incident laser radiation.
Combined effects of intense laser field, electric and magnetic fields on the nonlinear optical properties of the step-like quantum well
(ELSEVIER SCIENCE SA, 2015) Kasapoglu, E.; Duque, C. A.; Mora-Ramos, M. E.; Restrepo, R. L.; Ungan, F.; Yesilgul, U.; Sari, H.; Sokmen, I.
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 for transition between two lower-lying electronic levels in the step-like GaAs/Ga1-xAlxAs quantum well under external electric and magnetic fields are investigated. The calculations were performed within the compact density-matrix formalism with the use of the effective mass and parabolic band approximations. The obtained results show that both total absorption coefficient and refractive index change are sensitive to the well dimensions and the effects of external fields. By changing the intensities of the electric, magnetic and non-resonant intense laser fields together with the well dimensions, 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.
Donor impurity atom effect on the inter-subband absorption coefficient for symmetric double n-type ?-doped GaAs quantum well
(Academic Press Ltd- Elsevier Science Ltd, 2021) Rodriguez-Magdaleno, K. A.; Turkoglu, A.; Ungan, F.; Mora-Ramos, M. E.; Martinez-Orozco, J. C.
In this work, the electronic structure and the inter-subband absorption coefficient (IAC) are theoretically studied for symmetric double n-type delta-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 z(i) = 0). We found that the reported physical properties become more sensitive to the inter-well separation distance L-w than to the delta-doping density, N-2d. In the former case the total optical absorption coefficient undergoes an important red-shift as well as a significant decrease in its magnitude. When N-2d 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.
Donor impurity states and related optical responses in triangular quantum dots under applied electric field
(ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2014) Kasapoglu, E.; Ungan, F.; Sari, H.; Sokmen, I.; Mora-Ramos, M. E.; Duque, C. A.
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.
Donor Impurity-Related Optical Absorption in GaAs Elliptic-Shaped Quantum Dots
(HINDAWI LTD, 2017) Londono, M. A.; Restrepo, R. L.; Ojeda, J. H.; Huynh Vinh Phuc; Mora-Ramos, M. E.; Kasapoglu, E.; Morales, A. L.; Duque, C. A.
The conduction band and electron-donor impurity states in elliptic-shaped GaAs quantum dots under the effect of an externally applied electric field are calculated within the effective mass and adiabatic approximations using two different numerical approaches: a spectral scheme and the finite element method. The resulting energies and wave functions become the basic information needed to evaluate the interstate optical absorption in the system, which is reported as a function of the geometry, the electric field strength, and the temperature.
Effect of applied electric field on the nonlinear optical properties of modulation-doped GaAs/AlxGa1-x As double quantum well
(ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2019) Ungan, F.; Martinez-Orozco, J. C.; Restrepo, R. L.; Mora-Ramos, M. E.; Duque, C. A.
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.
Effect of applied external fields on the nonlinear optical properties of a Woods-Saxon potential quantum well
(ELSEVIER SCIENCE BV, 2019) Ungan, F.; Mora-Ramos, M. E.; Yesilgul, U.; Sari, H.; Sokmen, I
In this present work a detailed theoretical study on the influence of the static electric, magnetic, and nonresonant intense THz laser fields on the nonlinear optical properties such as nonlinear optical rectification (NOR) and second harmonic generation (SHG), of a quantum well that has the Woods-Saxon potential profile. The static electric and high-frequency intense THz laser fields are applied along the growth-direction of the structure whilst the static magnetic field is applied perpendicular to them. The outcome of the numerical calculation demonstrates that, both the peak potions of the NOR and SHG coefficients exhibit a blue-shift with the increment of the static electric and magnetic fields, but their peak amplitudes increases with the magnitude of the electric field whilst decreases with the magnitude of the magnetic field. However, the peak positions of the NOR and SHG coefficients exhibit firstly a blue-shift, and then a red-shift with the increment of the laser intensity, but their peak amplitudes increases. We hope that these theoretical results will be useful for designing new optoelectronic devices with a performance tailored by the adjustment of the applied fields.
Effect of intense high-frequency laser field on the linear and nonlinear intersubband optical absorption coefficients and refractive index changes in a parabolic quantum well under the applied electric field
(ELSEVIER SCIENCE BV, 2014) Yesilgul, U.; Ungan, F.; Sakiroglu, S.; Mora-Ramos, M. E.; Duque, C. A.; Kasapoglu, E.; Sari, H.; Sokmen, I.
The effects of the intense high-frequency laser field on the optical absorption coefficients and the refractive index changes in a GaAs/GaAlAs parabolic quantum well under the applied electric field have been investigated theoretically. The electron energy levels and the envelope wave functions of the parabolic quantum well are calculated within the effective mass approximation. Analytical expressions for optical properties are obtained using the compact density-matrix approach. The numerical results show that the intense high-frequency laser field has a large effect on the optical characteristics of these structures. Also we can observe that the refractive index and absorption coefficient changes are very sensitive to the electric field in large dimension wells. Thus, this result gives a new degree of freedom in the optoelectronic device applications. (C) 2013 Elsevier B.V. All rights reserved.
Effect of the magnetic field on the nonlinear optical rectification and second and third harmonic generation in double delta-doped GaAs quantum wells
(ELSEVIER SCIENCE BV, 2017) Martinez-Orozco, J. C.; Rojas-Briseno, J. G.; Rodriguez-Magdaleno, K. A.; Rodriguez-Vargas, I.; Mora-Ramos, M. E.; Restrepo, R. L.; Ungan, F.; Kasapoglu, E.; Duque, C. A.
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-d-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, chi((2))(0), chi((2))(2 omega), and chi((3))(3 omega), are those arising from the compact matrix density formulation and stand for the NOR, SHG, and THG, respectively. This asymmetric double d-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.
Effects of doping concentrations and position-dependent mass on the nonlinear optical properties of asymmetric double delta-doped GaAs quantum wells
(Springer Heidelberg, 2024) Durmuslar, A. Salman; Al, E. B.; Althib, H. M.; Mora-Ramos, M. E.; Ungan, F.
This study examines the electronic and optical properties of an asymmetric double delta doped quantum wells structure formed within GaAs. The electronic structure of system is obtained within effective mass and envelope wave function approximations. Optical responses are calculated in the framework of the compact density matrix approach. The roles of distance between wells, varying one well electron concentration, as well as length parameter of position-dependent mass, on the total optical absorption coefficients and the relative refractive index changes are investigated. The findings of this study indicate that prominence of optical coefficients occurs at higher energies for position-dependent mass, compared to constant mass case. Augmented right well electron concentrations lead to blue-shifts on the optical properties not only with constant mass but also with position-dependent mass. However, the increase in the wells' separation results the absorption peaks to move towards lower energies.
Effects of electromagnetic fields on the nonlinear optical properties of CrossMaric asymmetric double quantum well under intense laser field
(ELSEVIER SCIENCE BV, 2017) Yesilgul, U.; Sari, H.; Ungan, F.; Martinez-Orozco, J. C.; Restrepo, R. L.; Mora-Ramos, M. E.; Duque, C. A.; Sokmen, I.
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.
Effects of Geometry on the Electronic Properties of Semiconductor Elliptical Quantum Rings
(NATURE PUBLISHING GROUP, 2018) Vinasco, J. A.; Radu, A.; Kasapoglu, E.; Restrepo, R. L.; Morales, A. L.; Feddi, E.; Mora-Ramos, M. E.; Duque, C. A.
The electronic states in GaAs-AlxGa1-xAs elliptically-shaped quantum rings are theoretically investigated through the numerical solution of the effective mass band equation via the finite element method. The results are obtained for different sizes and geometries, including the possibility of a number of hill-shaped deformations that play the role of either connected or isolated quantum dots (hills), depending on the configuration chosen. The quantum ring transversal section is assumed to exhibit three different geometrical symmetries - squared, triangular and parabolic. The behavior of the allowed confined states as functions of the cross-section shape, the ring dimensions, and the number of hills-like structures are discussed in detail. The effective energy bandgap (photoluminescence peak with electron-hole correlation) is reported as well, as a function of the Al molar fraction.
Effects of hydrostatic pressure, temperature, and position-dependent mass on the nonlinear optical properties of triple delta-doped GaAs quantum well
(Springer Heidelberg, 2024) Tuzemen, A. Turker; Al, E. B.; Sayrac, H.; Dakhlaoui, H.; Mora-Ramos, M. E.; Ungan, F.
In this study, we thoroughly investigate the impacts of hydrostatic pressure, temperature, and position-dependent mass (PDM) on the nonlinear optical properties of asymmetric triple delta-doped GaAs quantum wells. Our analysis covers total optical absorption coefficients, relative refractive index changes, nonlinear optical rectification, second harmonic generation, and third harmonic generation. Initially, we employ PDM to solve the time-independent Schr & ouml;dinger equation using the diagonalization method under effective mass and parabolic band approaches, considering pressure and temperature dependencies. Utilizing the first four energy eigenvalues and eigenfunctions, we apply the compact density matrix method to compute the system's nonlinear optical properties numerically. The results indicate a shift in optical property peak positions toward lower (higher) energy spectra with increasing hydrostatic pressure (temperature). Furthermore, the influence of PDM shifts the system's optical properties toward the higher energy spectrum, resembling the effect of temperature. From an experimental and theoretical perspective, one of the topics that researchers work on most is GaAs-based delta-doped systems (delta-doped heterojunction bipolar transistors, delta-doped field effect transistors, delta-multiple independent gate field effect transistors, etc.). We believe these findings will provide valuable insights for the researchers involved in GaAs-based delta-doped optoelectronic device design.
The effects of intense laser field and applied electric and magnetic fields on optical properties of an asymmetric quantum well
(ELSEVIER SCIENCE BV, 2015) Restrepo, R. L.; Ungan, F.; Kasapoglu, E.; Mora-Ramos, M. E.; Morales, A. L.; Duque, C. A.
This paper presents the results of the theoretical study of the effects of non resonant intense laser field and electric and magnetic fields on the optical properties (the linear and third order nonlinear refractive index and absorption coefficients) in an asymmetric quantum well. The electric field and intense laser field are applied along the growth direction of the asymmetric quantum well and the magnetic field is oriented perpendicularly. To calculate the energy and the wave functions of the electron in the asymmetric quantum well, the effective mass approximation and the method of envelope wave function are used. The asymmetric quantum well is constructed by using different aluminium concentrations in both right and left barriers. The confinement in the quantum well is changed drastically by either the effect of electric and magnetic fields or by the application of intense laser field. The optical properties are calculated using the compact density matrix approach. The results show that the effect of the intense laser field competes with the effects of the electric and magnetic fields. Consequently, peak position shifts to lower photon energies due to the effect of the intense laser field and it shifts to higher photon energies by the effects of electric and magnetic fields. In general, it is found that the concentration of aluminum, electric and magnetic fields and intense laser field are external agents that modify the optical responses in the asymmetric quantum well. (C) 2014 Elsevier B.V. All tights reserved.
The effects of the electric and intense laser field on the binding energies of donor impurity states (1s and 2p(+/-)) and optical absorption between the related states in an asymmetric parabolic quantum well
(ELSEVIER SCIENCE BV, 2016) Kasapoglu, E.; Sakiroglu, S.; Sokmen, I.; Restrepo, R. L.; Mora-Ramos, M. E.; Duque, C. A.
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-c<0 (L-c>0), 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.
The effects of the electric and magnetic fields on the nonlinear optical properties in the step-like asymmetric quantum well
(ELSEVIER SCIENCE BV, 2014) Kasapoglu, E.; Ungan, F.; Duque, C. A.; Yesilgul, U.; Mora-Ramos, M. E.; Sari, H.; Sokmen, I.
In the present work, total optical absorption coefficient (the linear and third-order nonlinear) and total refractive index change for transition between two first lower-lying electronic levels in the step-like GaAs/Ga1-xAlxAs quantum well under the electric and magnetic fields are investigated and also the effect of relaxation time on saturation is investigated. A compact density-matrix approach is applied to investigate optical properties. The obtained results show that both total absorption coefficient and refractive index change are sensitive to well dimensions more than external fields. With the increase of quantum well width, total absorption coefficient and refractive index change shift to lower photon energies (red shift), the magnitude of total refractive index increases significantly while total absorption coefficient is reduced. Furthermore, the electric and magnetic fields induce a blue-shift on absorption coefficient and refractive index change. (C) 2014 Elsevier B.V. All rights reserve
The effects of the intense laser field on the nonlinear optical properties of a cylindrical Ga1-xAlxAs/GaAs quantum dot under applied electric field
(ELSEVIER SCIENCE BV, 2015) Kasapoglu, E.; Duque, C. A.; Mora-Ramos, M. E.; Sokmen, I.
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,
Electron Raman scattering in a double quantum well tuned by an external nonresonant intense laser field
(ELSEVIER SCIENCE BV, 2017) Tiutiunnyk, A.; Mora-Ramos, M. E.; Morales, A. L.; Duque, C. M.; Restrepo, R. L.; Ungan, F.; Martinez-Orozco, J. C.; Kasapoglu, E.; Duque, C. A.
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.
Electron-related nonlinear optical properties of cylindrical quantum dot with the Rosen-Morse axial potential
(Iop Publishing Ltd, 2020) Ungan, F.; Bahar, M. K.; Pal, S.; Mora-Ramos, M. E.
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 (eta, 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 eta, 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.

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