Effects of applied electric fields on optical responses in elliptical quantum nanosystems

The optical absorption response of an elliptical quantum-dot-type nanostructure is investigated by numerically determining the electron states within the effective mass and parabolic approximations via the finite element method, taking into account the effect of an externally applied electric field. Validation of the numerical procedure is discussed through the comparison with analytical results of previous works for zero external field conditions. For finite field, the comparison is made with the outcome of degenerate perturbation theory. The calculated electron energies and wavefunctions are used to evaluate the linear and nonlinear light absorption and refractive index change coefficients in the system. Their corresponding expressions are those typically derived within a perturbative approach for solving the density matrix equation of motion. It is shown how the electric field and the change in the elliptical geometry affect the optical response of the considered structures. The extension of the treatment to consider the properties of elliptic nanoparticles under external field influences is briefly discussed.