Studies On The Linear And Nonlinear Optical Properties Of A Two-particle Semiconductor Quantum Dot

With the advancement of nanotechnology§the study of low-dimensional systems suchas quantum wells, quantum wires and quantum dots (QDs) has received much attentionboth in experimental and theoretical investigations in the past dozens of years. QD is anew-style semiconductor material in which carriers are confined in all spatial dimensions.Hence its quantum mechanical efects are more distinct from quantum well and quantumwire. Nowadays, many kinds of technologies are applied to prepare various shapes andscales of QDs. With a great deal of theoretical calculation and experimental study, manypeculiar physical phenomena have been realized in QDs, i.e, coulomb blockade, tunnelingphenomenon, quantum entanglement and correlation. These properties can be used todesign quantum devices and quantum computers, etc. A large number of studies haveshown that the low-dimensional semiconductor materials are powerful nonlinear opticalmaterials. In this paper, we consider the nonlinear optical properties of a two-particlesystem theoretically under the influence of external field. Composed by the five chaptersof this thesis.In the first chapter, the basic knowledge of QDs, the possible application and themain properties of QDs are introduced systematically. The fabricated methods and themain theoretical research methods are also introduced.In the second chapter, the linear and nonlinear optical absorptions and refractive in-dex changes for an exciton in a parabolic QD are studied. The eigenfunctions and eigenen-ergies of the system are presented by using perturbation method with the efective-massapproximation. The analytical expression of the linear and nonlinear optical absorptionsand refractive index changes are given by employing the compact density matrix ap-proach. The dependence of the nonlinear optical properties on the applied electric field,confinement frequency, incident optical intensity and relaxation times is discussed.In the third chapter, the linear and nonlinear optical absorptions and refractive in-dex changes in a double-electron QD are studied. Using the perturbation method, wederive the eigenfunctions and eigenenergies of the system by considering the symmetry ofidentical particles. The efects of external electric field, confinement frequency, incidentoptical intensity and relaxation times on the nonlinear optical properties are investigated.In parallel, the nonlinear optical properties associated with double-electron and excitonin the same conditions are compared. In the fourth chapter, the efect of intense laser field on the electronic Raman S-cattering of shallow donor impurities in QDs is investigated. The eigenfunctions andeigenenergies of the system are derived by using a quasi-analytical approach. Numericalresults and discussions are presented for diferent values of the laser field and confinementstrength.In the last chapter, a brief summary of this paper, including the theories and themain results, is given. The shortage and the further research are also mentioned.