Optical absorption computation of a D2+ artificial molecule in GaAs/Ga1−xAlxAs nanometer-scale rings

Abstract

The linear and non-linear optical absorption coefficients of a D2+ artificial molecule confined in GaAs nano-scaled rings under a threading magnetic field were calculated. The results showed that by varying the position and the angle formed by the double-donor system, the total optical absorption can be enhanced, quenched, or even totally nullified. On the other hand, small changes of the optical response close to 2% due to external hydrostatic pressure fields or sample temperature variations within the ranges 0–30 kbar and 4–400 K, respectively, were obtained. In addition, reducing the aluminum concentration in the surrounding matrix significantly enhanced the optical absorption. A careful analysis was carried out in order to determine the conditions that will avoid an overflow of the wavefunction and that complement the previously obtained results. Furthermore, oscillatory behavior of the optical absorption with the magnetic field was observed. By increasing the QR's radius, a red-shift of the total optical absorption spectra was observed, allowing the tuning of the resonance peaks below 20 meV (also known as the THz band).