The third-order nonlinearity susceptibility is obtained as a function of wavelength for ZnS / CdSe / ZnS structure. Numerical calculations show that the nonlinear susceptibility of this structure depends on parameters such as structure size, relaxation time and pump photon energy. The intensity and position of third-order nonlinear susceptibility peaks depend on shell thicknesses; smaller thicknesses have peak susceptibility at shorter wavelength.

Third-order harmonics generation (THG) has been investigated for ZnS/CdSe/ZnS nanoshell structure. Numerical calculations show that THG susceptibility has two peaks and depends on the parameters such as the size and the kind of structure, the relaxation time and the pump photon energy. The intensity and position of third-order nonlinear susceptibility peaks depend on shell thicknesses; smaller thickness have peak susceptibility at shorter wavelengths.