Size Effect on Nonlinear Optical Properties in Cdse/Zns Core/Shell Spherical Quantum Dots: Towards Group Velocity Discussion

Abstract

We propose a theoretical investigation of group velocity performed in CdSe/ZnS core/shell quantum dot (CSQD) by exploiting the quantum confinement effect through the manipulation of several factors. The key difference occurs in the behavior of the electron, whose wavefunction is significantly altered into the core region leading to different optical properties. Energy eigenvalues and eigenvectors are computed using the effective mass approximation (E.M.A) and the optical properties are derived using the compact density matrix approach. Several critical influencing factors such as core radius, relaxation time, frequency and incident optical intensity have been investigated to examine the third order nonlinear susceptibility, refractive index changes, absorption coefficients and the group velocity. Our research underlines the strongly size dependent susceptibilities. Moreover, appropriate spatial factors could enhance the refractive index changes. The dependence of the absorption coefficient and the group velocity on dimension, photon frequency and optical intensity has been analyzed. The obtained results may find some potential applications in increasing the velocity of the information transmission in optical communications and laser technologies.

Keywords: Quantum confinement, effective mass approximation, absorption coefficients, group velocity, refractive index