In this present work, for different impurity position and ionized doping concentrations, we have ... more 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.
The effects of in-growth applied electric fields and in-plane (x-oriented) magnetic fields on the... more 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.
We present a theoretical study on the effects of intense laser field (ILF) and static electric fi... more 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, V1, 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, V1, 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.
In the present work, a detailed investigation of the influence of external perturbations, in part... more In the present work, a detailed investigation of the influence of external perturbations, in particular intense terahertz radiation, static electric and magnetic fields on the electron-related optical responses such as total optical absorption coefficients and relative refractive index changes for a quantum well with the square tangent potential is presented. The subband energy levels and their corresponding wave functions are obtained by solving the one-electron Hamiltonian of the system under the framework of the effective-mass and parabolic band approximations. Optical coefficients are reported for varying incident photon energies. The numerical results show that the optical response is shifted towards the blue with the increase in the magnitude of the applied external fields. These results can provide an input for use in optoelectronic device applications.
Impurity-related optical response in cylindrical quantum dots with a δ-doped axial potential unde... more Impurity-related optical response in cylindrical quantum dots with a δ-doped axial potential under an intense laser field,
This work presents the results of the theoretical study of the effects of non-resonant intense la... more This work presents the results of the theoretical study of the effects of non-resonant intense laser field, electric and magnetic fields on optical responses of GaAs n-type ı-doped quantum well associated to the electron transitions. Optical properties are obtained by using the compact-density matrix method. The numerical results show that the applied external fields have a significant effect on the optical characteristics of these structures, such as the optical absorption coefficient and refractive index. Thus, such futures can be use to tune the optical properties of doped semiconductor heterostructures.
Abstract In the present study, the effects of electric and magnetic fields on the linear and thir... more Abstract In the present study, the effects of electric and magnetic fields on the linear and third-order nonlinear optical absorption coefficients and relative change of the refractive index in asymmetric GaAs/GaAlAs double quantum wells under intense laser fields are theoretically investigated. The electric field is oriented along the growth direction of the heterostructure while the magnetic field is taken in-plane. The intense laser field is linear polarization along the growth direction. Our calculations are made using the effective-mass approximation and the compact density-matrix approach. Intense laser effects on the system are investigated with the use of the Floquet method with the consequent change in the confinement potential of heterostructures. Our results show that the increase of the electric and magnetic fields blue-shifts the peak positions of the total absorption coefficient and of the total refractive index while the increase of the intense laser field firstly blue-shifts the peak positions and later results in their red-shifting.
Using a variational approach, we have investigated the effects of the magnetic field, the impurit... more Using a variational approach, we have investigated the effects of the magnetic field, the impurity position, and the nitrogen and indium concentrations on impurity binding energy in a Ga 1−x In x N y As 1−y /GaAs quantum well. Our calculations have revealed the dependence of impurity binding on the applied magnetic field, the impurity position, and the nitrogen and indium concentrations.
This paper presents the results of the theoretical study of the effects of non-resonant intense l... more 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.
ABSTRACT In the present work, the effects of electric and magnetic fields on the optical absorpti... more ABSTRACT 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-xAsGaAs/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.
The GaAs n-type delta-doped field effect transistor is proposed as a source for nonlinear optical... more The GaAs n-type delta-doped field effect transistor is proposed as a source for nonlinear optical responses such as second order rectification and second and third harmonic generation. Particular attention is paid to the effect of hydrostatic pressure on these properties, related with the pressureinduced modifications of the energy level spectrum. The description of the one-dimensional potential profile is made including Hartree and exchange and correlation effects via a Thomas-Fermi-based local density approximation. The allowed energy levels are calculated within the effective mass and envelope function approximations by means of an expansion over an orthogonal set of infinite well eigenfunctions. The results for the coefficients of nonlinear optical rectification and second and third harmonic generation are reported for several values of the hydrostatic pressure.
Effect of intense high-frequency laser field on the linear and nonlinear intersubband optical abs... more 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,
The 1s-like and 2p-like donor impurity energy states are studied in a semiconductor quantum wire ... more The 1s-like and 2p-like donor impurity energy states are studied in a semiconductor quantum wire of equilateral triangular cross section as functions of the impurity position and the geometrical size of the structure. Linear and nonlinear coefficients for the optical absorption and relative refractive index change associated with 1s-2p transitions are calculated for both the x-polarization and y-polarization of the incident light. The results show a mixed effect of redshift and blueshift depending on the location of the donor atom. Also, strong nonlinear contributions to the optical absorption coefficient are obtained for both polarizations in the on-center impurity case.
By using the eective mass and parabolic band approximations, the nonlinear optical rectication an... more By using the eective mass and parabolic band approximations, the nonlinear optical rectication and the second harmonic generation are calculated in a two-dimensional quantum ring under the simultaneous eects of perpendicularly applied magnetic eld and in-plane applied electric eld. The geometry of the ring is modeled via the combined inuences of a parabolic and inverse square conning potentials. The exact solutions for the two-dimensional motion of the conduction band electrons are used as the basis for a perturbation-theory treatment of the static electric eld eect. The variation of one of the dierent potential energy parameters, for a xed conguration of the remaining ones, leads to either blueshifts or redshifts of the resonant peaks as well as to distinct rates of change for their amplitudes.
Physica E: Low-dimensional Systems and Nanostructures, 2014
ABSTRACT The linear and nonlinear coefficients for the optical absorption and relative refractive... more ABSTRACT The linear and nonlinear coefficients for the optical absorption and relative refractive index change associated with intersubband transitions of electrons in the conduction band of a two-dimensional quantum dot of triangular shape are calculated for x-polarization and y-polarization of the incident light. Both the effective mass and parabolic band approximations have been considered. The results show that the increase in the size of the triangular quantum dot leads to the expected fall of the intersubband energy transition and that there is an increment in the values of the associated off-diagonal electric dipole moment matrix elements. All this reflects in the increase of the amplitude of the nonlinear optical absorption resonant peak, as well as in the growth of the total relative refractive index in the system.
In this present work, for different impurity position and ionized doping concentrations, we have ... more 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.
The effects of in-growth applied electric fields and in-plane (x-oriented) magnetic fields on the... more 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.
We present a theoretical study on the effects of intense laser field (ILF) and static electric fi... more 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, V1, 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, V1, 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.
In the present work, a detailed investigation of the influence of external perturbations, in part... more In the present work, a detailed investigation of the influence of external perturbations, in particular intense terahertz radiation, static electric and magnetic fields on the electron-related optical responses such as total optical absorption coefficients and relative refractive index changes for a quantum well with the square tangent potential is presented. The subband energy levels and their corresponding wave functions are obtained by solving the one-electron Hamiltonian of the system under the framework of the effective-mass and parabolic band approximations. Optical coefficients are reported for varying incident photon energies. The numerical results show that the optical response is shifted towards the blue with the increase in the magnitude of the applied external fields. These results can provide an input for use in optoelectronic device applications.
Impurity-related optical response in cylindrical quantum dots with a δ-doped axial potential unde... more Impurity-related optical response in cylindrical quantum dots with a δ-doped axial potential under an intense laser field,
This work presents the results of the theoretical study of the effects of non-resonant intense la... more This work presents the results of the theoretical study of the effects of non-resonant intense laser field, electric and magnetic fields on optical responses of GaAs n-type ı-doped quantum well associated to the electron transitions. Optical properties are obtained by using the compact-density matrix method. The numerical results show that the applied external fields have a significant effect on the optical characteristics of these structures, such as the optical absorption coefficient and refractive index. Thus, such futures can be use to tune the optical properties of doped semiconductor heterostructures.
Abstract In the present study, the effects of electric and magnetic fields on the linear and thir... more Abstract In the present study, the effects of electric and magnetic fields on the linear and third-order nonlinear optical absorption coefficients and relative change of the refractive index in asymmetric GaAs/GaAlAs double quantum wells under intense laser fields are theoretically investigated. The electric field is oriented along the growth direction of the heterostructure while the magnetic field is taken in-plane. The intense laser field is linear polarization along the growth direction. Our calculations are made using the effective-mass approximation and the compact density-matrix approach. Intense laser effects on the system are investigated with the use of the Floquet method with the consequent change in the confinement potential of heterostructures. Our results show that the increase of the electric and magnetic fields blue-shifts the peak positions of the total absorption coefficient and of the total refractive index while the increase of the intense laser field firstly blue-shifts the peak positions and later results in their red-shifting.
Using a variational approach, we have investigated the effects of the magnetic field, the impurit... more Using a variational approach, we have investigated the effects of the magnetic field, the impurity position, and the nitrogen and indium concentrations on impurity binding energy in a Ga 1−x In x N y As 1−y /GaAs quantum well. Our calculations have revealed the dependence of impurity binding on the applied magnetic field, the impurity position, and the nitrogen and indium concentrations.
This paper presents the results of the theoretical study of the effects of non-resonant intense l... more 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.
ABSTRACT In the present work, the effects of electric and magnetic fields on the optical absorpti... more ABSTRACT 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-xAsGaAs/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.
The GaAs n-type delta-doped field effect transistor is proposed as a source for nonlinear optical... more The GaAs n-type delta-doped field effect transistor is proposed as a source for nonlinear optical responses such as second order rectification and second and third harmonic generation. Particular attention is paid to the effect of hydrostatic pressure on these properties, related with the pressureinduced modifications of the energy level spectrum. The description of the one-dimensional potential profile is made including Hartree and exchange and correlation effects via a Thomas-Fermi-based local density approximation. The allowed energy levels are calculated within the effective mass and envelope function approximations by means of an expansion over an orthogonal set of infinite well eigenfunctions. The results for the coefficients of nonlinear optical rectification and second and third harmonic generation are reported for several values of the hydrostatic pressure.
Effect of intense high-frequency laser field on the linear and nonlinear intersubband optical abs... more 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,
The 1s-like and 2p-like donor impurity energy states are studied in a semiconductor quantum wire ... more The 1s-like and 2p-like donor impurity energy states are studied in a semiconductor quantum wire of equilateral triangular cross section as functions of the impurity position and the geometrical size of the structure. Linear and nonlinear coefficients for the optical absorption and relative refractive index change associated with 1s-2p transitions are calculated for both the x-polarization and y-polarization of the incident light. The results show a mixed effect of redshift and blueshift depending on the location of the donor atom. Also, strong nonlinear contributions to the optical absorption coefficient are obtained for both polarizations in the on-center impurity case.
By using the eective mass and parabolic band approximations, the nonlinear optical rectication an... more By using the eective mass and parabolic band approximations, the nonlinear optical rectication and the second harmonic generation are calculated in a two-dimensional quantum ring under the simultaneous eects of perpendicularly applied magnetic eld and in-plane applied electric eld. The geometry of the ring is modeled via the combined inuences of a parabolic and inverse square conning potentials. The exact solutions for the two-dimensional motion of the conduction band electrons are used as the basis for a perturbation-theory treatment of the static electric eld eect. The variation of one of the dierent potential energy parameters, for a xed conguration of the remaining ones, leads to either blueshifts or redshifts of the resonant peaks as well as to distinct rates of change for their amplitudes.
Physica E: Low-dimensional Systems and Nanostructures, 2014
ABSTRACT The linear and nonlinear coefficients for the optical absorption and relative refractive... more ABSTRACT The linear and nonlinear coefficients for the optical absorption and relative refractive index change associated with intersubband transitions of electrons in the conduction band of a two-dimensional quantum dot of triangular shape are calculated for x-polarization and y-polarization of the incident light. Both the effective mass and parabolic band approximations have been considered. The results show that the increase in the size of the triangular quantum dot leads to the expected fall of the intersubband energy transition and that there is an increment in the values of the associated off-diagonal electric dipole moment matrix elements. All this reflects in the increase of the amplitude of the nonlinear optical absorption resonant peak, as well as in the growth of the total relative refractive index in the system.
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