Search

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 FROM AUTHOR]

Abstract In the current work, the nonlinear optical properties in GaAs/Ga 1− x Al x As semiparabolic and parabolic quantum well(QW) with constant effective mass(CEM) and position dependent effective mass(PDEM) are estimated for different applied magnetic field. In this regard, we have obtained the analytical expressions of the nonlinear rectification(OR), second harmonic generation(SHG), third harmonic generation(THG), optical absorption coefficients(OACs), and refractive index changes(RICs) by using the compact density matrix formalism. Simultaneously, we obtain the reliable energy eigenvalues and their corresponding eigenfunctions via the finite difference method. According to the obtained results, it is found that: (1)the correct inclusion of PDEM is the cause of a noticeable difference in nonlinear optical properties with respect to the use of CEM. (2)the applied magnetic field bear substantial technological importance in the process of nonlinear optical properties modulation. Highlights • The nonlinear optical properties semiparabolic and parabolic QW with CEM and PDEM have been discussed. • We obtain the energy eigenvalues and their corresponding eigenfunctions via the fine difference method. • The effect of applied magnetic field B are also studied in their competition with CEM and PDEM. • Nanostructures possess considerably different behaviors under CEM and PDEM. [ABSTRACT FROM AUTHOR]

In this work, the simultaneous effects of aluminum concentration, hydrostatic pressure and temperature on the nonlinear optical rectification (OR), second- and third-harmonic generation (SHG and THG) in a GaAs/Ga 1 − x Al x As morse quantum well (QW) are studied. The expressions of OR, SHG and THG in morse QW were derived with the use of the compact-density-matrix approach and iterative method. The simultaneous effects of aluminum concentration, hydrostatic pressure and temperature on the effective mass have been taken into account. It is found that (1) the presence of the aluminum concentration, hydrostatic pressure and temperature have a great influence on the symmetry of the system, the nonlinear OR, SHG and THG. (2) the variation of the resonant peaks of the OR and SHG shows complicated behavior as the temperature changes. (3) the temperature effect is weaker than the aluminum concentration and hydrostatic pressure effects on the nonlinear OR, SHG and THG. The influences of different parameters of GaAs/Ga 1 − x Al x As morse QW and applied field strengths on the nonlinear OR, SHG and THG are discussed. [ABSTRACT FROM AUTHOR]

The second harmonic generation(SHG) and third harmonic generation(THG) of a GaAs/GaAlAs exponential quantum well(QW) are numerically investigated in the presence of applied electric and magnetic field, which are parallel to the QW growth direction. The eigenvalues and corresponding eigenfunctions of the system are obtained by using the finite difference technique. The expression for the second- and third-order susceptibility is given by the density matrix and iterative approach. It is showed that, the SHG and THG not only depend strongly on quantum confinement, but also the intensity of external fields. We have systematically studied the SHG and THG of different confinement QWs by adjusting the structural parameters, as well as the effects of external electric and magnetic fields. We give the optimal system parameters in which the external field effects play important role. [ABSTRACT FROM AUTHOR]

In this present study, the effect of electron-LO-phonon interaction on the refractive index changes (RICs) in a Modified-Pöschl–Teller quantum well (QW) is theoretically investigated within the framework of the compact density matrix approach and iterative method. The energy eigenvalues and their corresponding eigenfunctions of the system under the influence of electron-LO-phonon interaction are calculated with the non-degenerate perturbation method. The results show that the RICs are strongly affected by the well depth and well width of the QW system. Moreover, the theoretical values of the RICs are obviously increased when considering the electron-LO-phonon interaction. [ABSTRACT FROM AUTHOR]

Studies aimed at understanding the nonlinear optical (NLO) properties of GaAs/Ga0.7Al0.3As morse quantum well (QW) have focused on the intersubband optical absorption coefficients (OACs) and refractive index changes (RICs). These studies have taken two complimentary approaches: (1) The compact-density-matrix approach and iterative method have been used to obtain the expressions of OACs and RICs in morse QW. (2) Finite difference techniques have been used to obtain energy eigenvalues and their corresponding eigenfunctions of GaAs/Ga0.7Al0.3As morse QW under an applied magnetic field, hydrostatic pressure, and temperature. Our results show that the hydrostatic pressure and magnetic field have a significant influence on the position and the magnitude of the resonant peaks of the nonlinear OACs and RICs. Simultaneously, a saturation case is observed on the total absorption spectrum, which is modulated by the hydrostatic pressure and magnetic field. Physical reasons have been analyzed in depth. [ABSTRACT FROM AUTHOR]

The investigation of the comprehensive influence of temperature and hydrostatic pressure on the nonlinear optical absorption coefficients(OACs), optical rectification(OR), second harmonic generation(SHG) and third harmonic generation(THG) in a Kratzer-Fues confined quantum well(QW) is carried out by means of the effective-mass approximation and density matrix formalism. The findings indicate that the nonlinear optical properties(OACs, OR, SHG, THG) are significantly different in response to temperature and hydrostatic pressure. Simultaneously, we find that the effects of temperature and hydrostatic pressure on the nonlinear OACs, OR, SHG and THG in this system are more pronounced. So the magnitude and the red and blue shift in the position of the OACs, OR, SHG and THG can be adjusted by changing the strength of the temperature and hydrostatic pressure, thus promoting the development of the optical modulators and miscellaneous device applications based on the nonlinear properties. • The OACs, OR, SHG and THG in Kratzer-Fues QW are studied. • We obtain the energy eigenvalues and eigenfunctions via the fine difference method. • The effect of P and T on these important optical quantity are also studied. • Nanostructures possess considerably different behaviors under P and T. [ABSTRACT FROM AUTHOR]