Abstract The paper examines the linear and non-linear optical characteristics of an electron in harmonic Gaussian asymmetrical double quantum wells, taking into account thermodynamic variables such as temperature and hydrostatic pressure. Numerical calculations by considering the effective mass and parabolic band approximation are performed. The electron contained within an asymmetric double well generated by the sum of a parabolic and Gaussian potential has its eigenvalues and eigenfunctions determined using the diagonalization approach. For nonlinear optical coefficients, the density matrix expansion is used. Wavefunctions and energy levels vary as an effect of the applied fields. In harmonic Gaussian asymmetrical double quantum wells, the total optical absorption coefficient (TOAC), the relative refractive index changes (RRIC), and second harmonic generation (SHG) have all been theoretically investigated. The magnitude and position of the resonant peaks are significantly influenced by the hydrostatic pressure and temperature effects. With controllable coupling and externally applied hydrostatic pressure and temperature, the potential model presented in this study can be used to simulate and manipulate the optical and electronic properties of the asymmetric double-quantum heterostructures, such as double quantum dots and wells.
Abstract The paper examines the linear and non-linear optical characteristics of an electron in harmonic Gaussian asymmetrical double quantum wells, taking into account thermodynamic variables such as temperature and hydrostatic pressure. Numerical calculations by considering the effective mass and parabolic band approximation are performed. The electron contained within an asymmetric double well generated by the sum of a parabolic and Gaussian potential has its eigenvalues and eigenfunctions determined using the diagonalization approach. For nonlinear optical coefficients, the density matrix expansion is used. Wavefunctions and energy levels vary as an effect of the applied fields. In harmonic Gaussian asymmetrical double quantum wells, the total optical absorption coefficient (TOAC), the relative refractive index changes (RRIC), and second harmonic generation (SHG) have all been theoretically investigated. The magnitude and position of the resonant peaks are significantly influenced by the hydrostatic pressure and temperature effects. With controllable coupling and externally applied hydrostatic pressure and temperature, the potential model presented in this study can be used to simulate and manipulate the optical and electronic properties of the asymmetric double-quantum heterostructures, such as double quantum dots and wells.
Abstract In this study, the effects of hydrostatic pressure and temperature on nonlinear optical rectification (OR), second-harmonic generation (SHG), third-harmonic generation (THG) and the linear, nonlinear, and total optical absorption coefficients (OACs) of a semiparabolic plus semi-inverse squared quantum well (QW) are theoretically investigated. The results show that hydrostatic pressure and temperature have significant effects on the optical properties of semiparabolic plus semi-inverse squared QWs, and that the energy levels and magnitudes of the resonant peaks of OR, SHG, THG, and the total OACs vary according to the shape of the limiting potential, the hydrostatic pressure, and the temperature. It is easily seen that the peak positions of the resonant peaks of OR, SHG, THG, and the total OACs in the semiparabolic plus semi-inverse squared QW show a red shift with increasing hydrostatic pressure, but a blue shift with increasing temperature. Therefore, the magnitude and position of the resonant peaks of OR, SHG, THG, and the total OACs can be adjusted by changing the hydrostatic pressure and the temperature, which promise a new degree of freedom in the tunability of various electro-optical devices.
Abstract 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 δ-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 Schrödinger 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 δ-doped systems (δ-doped heterojunction bipolar transistors, δ-doped field effect transistors, δ-multiple independent gate field effect transistors, etc.). We believe these findings will provide valuable insights for the researchers involved in GaAs-based δ-doped optoelectronic device design.
We have examined theoretically how the temperature and the hydrostatic pressure affect the total optical absorption coefficients, the total refractive index changes, and the second harmonic generation coefficients for GaAs/GaAlAs zigzag quantum well structure. The diagonalisation method and the effective mass approximation have been used to obtain the numerical solution of the Schrödinger equation and energy levels, respectively. The analytical expressions of the optical properties were obtained by using the compact density matrix and iterative methods. When the temperature (hydrostatic pressure) is increased, the resonant peaks’ positions of the total optical absorption coefficients and the relative refractive index changes are shifted to higher energies/blueshift (lower energies/red-shift) with amplitude increment (decrement). Additionally, the resonant peak position of the second harmonic generation coefficient shifts to higher energies/blueshift (lower energies) and also decrease (increase) in magnitude with increasing temperature (hydrostatic pressure).
In this paper, we explore the optical properties of AlGaAs/GaAs semi-parabolic quantum well (QW) under different temperature, hydrostatic pressure and applied magnetic field. We calculate the nonlinear optical absorption coefficients and the refractive index changes (RICs) with the compact density-matrix approach and iterative method. Then, within the framework of the effective mass and parabolic-band approximations, the energy eigenvalues and the corresponding wave functions for semi-parabolic QW have been obtained by the finite difference method. The theoretical findings show that (1) the energy spectrum depends strongly on temperature, hydrostatic pressure and applied magnetic field; (2) the linear and third-order nonlinear optical absorption coefficients and the RICs are quite sensitive to temperature, hydrostatic pressure and applied magnetic field. Our study provides a theoretical basis for the fabrication of QW structure.
Abstract In this paper, the effects of external electric, magnetic and non-resonant intense laser fields on the nonlinear optical rectification (NOR), second-harmonic (SH), and third-harmonic (TH) generation in a GaAs quantum well with asymmetrical Gaussian potential are theoretically investigated. Firstly, the energy eigenvalues and eigenfunctions of a single electron confined in the structure are obtained by using the diagonalization method within the framework of the effective-mass and parabolic band approaches. Then, using these energy eigenvalues and eigenfunctions, expressions derived within the compact density matrix approximation has been employed to calculate the coefficients of the nonlinear optical response in the structure. The obtained simulation results show that the influence of the external fields leads to significant changes in the coefficients of nonlinear optical rectification, second and third harmonic generation in the system. As a result, it has been seen that the amplitude and position of the peaks of nonlinear optical rectification, second and third harmonic coefficients can be controlled by changing the applied external fields.
In this paper, we investigate the electronic and optical properties of an electron in both symmetric and asymmetric double quantum wells that consist of a harmonic potential with an internal Gaussian barrier under a nonresonant intense laser field. The electronic structure was obtained by using the two-dimensional diagonalization method. To calculate the linear and nonlinear absorption, and refractive index coefficients, a combination of the standard density matrix formalism and the perturbation expansion method was used. The obtained results show that the electronic and thereby optical properties of the considered parabolic-Gaussian double quantum wells could be adjusted to obtain a suitable response to specific aims with parameter alterations such as well and barrier width, well depth, barrier height, and interwell coupling, in addition to the applied nonresonant intense laser field.