Characteristics of degenerated four wave mixing in ZnS/CdSe/ZnS quantum dot quantum well with multi-shell structure

The wave functions and eigenenergies of electrons in ZnS/CdSe/ZnS cylindrical quantum dot quantum well (QDQW) have been calculated by solving a three-dimensional nonlinear Schrödinger equation, in the framework of the effective-mass envelope-function theory. The third-order susceptibilities of the degenerated four waves mixing (DFWM) have been calculated theoretically by means of compact density matrix. The third-order susceptibilities as the function of the shell radius R2, R3 have been analyzed. The results show that the magnitude of nonlinear susceptibility is increased with the increasing of well radius. The resonance frequency of the photon have a shift when R2 or R3 is increasing and the relation between nonlinear susceptibility and relaxation time has also been studied.