A Theoretical Study on the Optical Properties of Low Dimensional Nanostructures

Abstract

The linear, the third order nonlinear optical absorption and the third harmonic generation susceptibility have been investigated by using the density matrix technique. The confinement potential has been taken to be a combination of a parabolic and inverse squared part. The study is distinct from previous studies by including the effect of a central or off-central hydrogenic impurity located in different positions. In the absence of impurity exact analytical solutions in terms of the associated Laguerre polynomials have been derived. However, in the presence of impurity the resulting Schro ̈dinger equation has been solved by applying the varitional method. In the case of a two dimensional disk shaped quantum dot in the presence of a magnetic field the linear and nonlinear optical absorption coefficients have been calculated. The presence of an impurity causes a huge increase in the square of the main transition matrix |M_21 |^2 and in the absorption coefficients. In the case of semi-parabolic and semi-inverse squared quantum well the third harmonic generation (THG) has been investigated. Its imaginary part has also been displayed. This part yields valuable information concerring the third order absorption coefficient.

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