Nonlinear optical properties of semiconductor heterostructures

Yıldırım, Hasan
The nonlinear optical properties of semiconductor heterostructures, such as GaAsAl/GaAs alloys, are studied with analytic and numerical methods on the basis of quantum mechanics. Particularly, second and third-order nonlinear optical properties of quantum wells described by the various types of confining potentials are considered within the density matrix formalism. We consider a Pöschl-Teller type potential which has been rarely considered in this area. It has a tunable asymmetry parameter, making it a good candidate to investigate the effect of the asymmetry on the nonlinear optical properties. The calculated nonlinear quantities include nonlinear absorption coefficient, second-harmonic generation, optical rectification, third-harmonic generation and the intensity-dependent refractive index. The effects of the DC electric field on the corresponding nonlinearities are also studied. The results are in good agreement with the results obtained in other types of quantum wells, such as square and parabolic quantum wells. The effects of the Coulomb interaction among the electrons on the nonlinear intersubband absorption are considered within the rotating wave approximation. The result is applied to a Si-delta-doped, square quantum well in which the Coulomb interaction among the electrons are relatively important, since there has been no work on the nonlinear absorption spectrum of the Si-\delta-doped quantum well. The results are found to be new and interesting, especially when a DC electric field is included in the calculations.


Exciton related nonlinear optical properties of a spherical quantum dot
Aksahin, E.; Unal, V. Ustoglu; Tomak, Mehmet (2015-11-01)
The nonlinear optical properties of an exciton in a spherical quantum dot (QD) is studied analytically. The nonlinear optical coefficients are calculated within the density matrix formalism. The electronic problem is solved within the effective mass approximation. The contributions from the competing effects of the confinement, the Coulomb interaction, and the applied electric field are calculated and compared with each other. We have made no assumptions about the strength of the confinement. We concentrate...
Nonlinear optical properties of a Woods-Saxon quantum dot under an electric field
AYTEKİN, ÖZLEM; Turgut, Sadi; Unal, V. Ustoglu; Aksahin, E.; Tomak, Mehmet (Elsevier BV, 2013-12-01)
A theoretical study of the effect of the confining potential on the nonlinear optical properties of two dimensional quantum dots is performed. A three-parameter Woods-Saxon potential is used within the density matrix formalism. The control of confinement by three parameters and an applied electric field gives one quite an advantage in studying their effects on the nonlinear properties. The coefficients investigated include the optical rectification, second and third-harmonic generation and the change in the...
Interacting electrons in a 2D quantum dot
Akman, N; Tomak, Mehmet (1999-04-01)
The exact numerical diagonalization of the Hamiltonian of a 2D circular quantum dot is performed for 2, 3, and 4 electrons. The results an compared with those of the perturbation theory. Our numerical results agree reasonably well for small values of the dimensionless coupling constant lambda = a/a(B) where a is the dot radius and a(B) is the effective Bohr radius. Exact diagonalization results are compared with the classical predictions, and they are found to be almost coincident for large lambda values.
Hermitian and gauge-covariant Hamiltonians for a particle in a magnetic field on cylindrical and spherical surfaces
Shikakhwa, M. S.; Chair, N. (IOP Publishing, 2017-01-01)
We construct the Hermitian Schrodinger Hamiltonian of spin-less particles and the gauge-covariant Pauli Hamiltonian of spin one-half particles in a magnetic field, which are confined to cylindrical and spherical surfaces. The approach does not require the use of involved differential-geometrical methods and is intuitive and physical, relying on the general requirements of Hermicity and gauge-covariance. The surfaces are embedded in the full three-dimensional space and confinement to the surfaces is achieved...
Nonlinear optical properties of a Poschl-Teller quantum well under electric and magnetic fields
AYTEKİN, ÖZLEM; Turgut, Sadi; Tomak, Mehmet (2012-04-01)
The nonlinear optical properties of a Poschl-Teller Quantum well (PTQW) under electric and magnetic fields are studied. The salient feature of this potential is its flexibility. It can be made asymmetrical by a proper choice of its two parameters. Optical rectification, second and third-harmonic generation susceptibilities are calculated using the density matrix formalism. We study the effects of quantum confinement, electric and magnetic fields on all of these optical coefficients.
Citation Formats
H. Yıldırım, “Nonlinear optical properties of semiconductor heterostructures,” Ph.D. - Doctoral Program, Middle East Technical University, 2006.