Optimization of the Second Harmonic Generation in a Realistic Model of Two Coupled Lens-Shaped Core/Shell Quantum Dots for Terahertz Applications (Pages 49-56)
Choubani, H. Maaref and F. Saidi
Departement of Physique, Laboratoire de Micro-Optoélectronique et Nanostructure (LR99ES29), Faculty of Sciences Monastir, University of Monastir, Tunisia
Abstract: In this paper, we make a perfect study of the Second Harmonic Generation coefficient of two coupled InAs/GaAs core/shell quantum dots. The discrete intra-band confined energy levels and their corresponding envelope wave functions are calculated implicitly via the Finite Difference Method of second order. The Second Harmonic Generation has been adjusted and controlled for terahertz applications when numerous important parameters such as: pressure, temperature , wetting layer, inter-dot separation distance, core dimensions and shell sizes assumed different values. It is found that the Second Harmonic Generation magnitude is strongly affected by the spacer width between the coupled lens-shaped quantum dots and a red/blue- shift is induced. Also, observations indicate the possibility of tailoring the shell’s width, consequently the encapsulation layer. In addition, It is found that the considered realistic model of lens-shaped form of the considered nanostructure causes a red-shift of the Second Harmonic Generation spectrum as compared to a spherical model. Moreover, obtained results also reveal that as the temperature (pressure) increases, the Second Harmonic Generation spectrum experiences a blue-shift (red-shift). Furthermore, other significant results are that the Second Harmonic Generation coefficient of coupled core/shell quantum dots is influenced significantly as compared to a single core/shell and the considered structure would be useful in various applications in terahertz region.
Keywords: Core/shell, Hydrostatic pressure, Lens-shaped quantum dots, Second Harmonic Generation, Temperature.