The linear and nonlinear optical properties of CuIn1−xGaxSe2 free standing nanowire have been studied by employing the compact-density matrix formalism and the effective mass approximation. Considering the system under the effect of the polarization vector of the incident light in both cases perpendicular and parallel to the axis of the nanowire, the systematic theoretical investigation contains results with all possible combinations of the involved parameters, such as incident light intensity, relaxation time, nanowire radius and Ga concentration. Our results show that in the case of the polarization vector perpendicular to the nanowire axis, the linear and nonlinear absorption coefficient and refractive index changes can be controlled by changing the nanowire radius, and the effect of Ga concentration is clearly apparent. In contrast, polarization along the nanowire axis allows for a very large absorption coefficient and control of the optical properties through the height, but minimal effect on the transition energy. The increase of the relaxation time as well as the intensity of the incident light has a major role in the nonlinearity effects, while the Ga concentration and the size of the structure influence the amplitude and the transition energy shift.

Within the framework of the effective mass approximation, a detailed investigation of the effects of an external (DC) electric field on the electronic and optical properties of a multi-layer cylindrical ZnS/ZnO quantum dot with fixed height and radius respectively at 10 nm and 5 nm, while modeling the ZnO wells using a parabolic potential. Numerical results were carried out using the Finite Difference Method (FDM), in order to compute the confinement energies, probability densities, expectation value for the potential describing a (DC) electric field for both the ground state and first excited state, and finishes by deducing the transition energy, transition dipole moment (TDM) and the absorption coefficient (AC) while taking into account multiple layer thickness configurations as we vary the electric field strength $F$. The results shows that varying the (DC) electric field strength does has an noticeable impact on the electronic and optical properties while all other inputs are kept unchanged.