Investigation of the third-order nonlinear optical susceptibilities associated with intersubband transitions in CdSe/ZnS/SiO2 core/shell/shell quantum dot

Using the one band effective mass approximation model we computed the optical properties for the spherical shape CdSe/ZnS/SiO2 core/shell/shell quantum dot (CSSQD). We calculated the charge carrier energies and corresponding wave functions. We investigated the radiative recombination lifetime of CSSQD nanocrystal, we found that the radiative lifetime is increased when we added the SiO2 layer for the CdSe/ZnS core/shell quantum dots. Then we calculated the nonlinear susceptibilities associated with intersubband transitions in the conduction band for CdSe/ZnS/SiO2 spherical CSSQD, and the third-order susceptibilities for quadratic electro-optic effects as a function of the core, shell radii and pump photo energy involving the position of energy levels also have been analyzed. The results show that the dot size plays a fundamental role in determining the nonlinear optical properties of quantum dots. Indeed, we see that the variation of the size of CdSe core has a more remarkable effect on nonlinear susceptibilities than the change in the thickness of the ZnS layer, and the variation of the SiO2 layer thickness has a negligible effect. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.