Non-linear response under terahertz radiation of an asymmetric Ga1-xAlxAs/GaAs/Ga1-yAlyAs V-groove nanowire confining a singly-ionized double donor

The non-linear optical rectification (NOR), the generation of the second (SHG) and third harmonic (THG) of a singly ionized double donor (SIDD) confined in an asymmetric Ga1-xAlxAs/GaAs/Ga1-yAlyAs V-groove nanowire are theoretically calculated. The calculated energy levels exhibit a molecular-like behavior with anticrossing points due to V-groove's pinch-offs. The carefully selected morphological parameters values of the V-groove allowed tuning the optical coefficients within the THz band. The NOR, SHG, and THG were found to be strongly dependent on the donor-donor distance. Larger values of the NOR for the SIDD in comparison to the single electron system were obtained. In contrast, larger values of the SHG and THG coefficients for single electrons can be calculated compared to the SIDD at small donor-donor distances.