  In this work, the changes in the energy of electrons and holes, oscillator
strength and interband transition time when external fields are applied to a
GaAs/AlGaAs semiconductor double ring grown by the droplet epitaxy technique
are theoretically analyzed. We consider a static electric field and an intense
laser field nonresonant with the quantum structure, with variable intensities
and orientations with respect to the symmetry axis of the quantum ring. In the
formalism of the effective mass approximation for electrons and holes, the
energies and wavefunctions were numerically computed using the finite element
method implemented with an accurate three-dimensional model of the real quantum
ring. Laser dressing of the confining potential was performed using the exact
integration formula at each point. Our results show major differences between
the effects of the two types of applied fields, caused mainly by the static
electric-field-induced strong polarizability of the confined electron-hole
pair. In addition, the effects of both fields exhibit strong anisotropy in the
electronic properties as a result of the particular flattened geometry of the
quantum ring. Proper combinations of field strengths and orientations are
helpful in designing accurate tools for the sensitive manipulation of interband
radiative properties.
