The third-order nonlinear optical susceptibility in an ellipsoidal core-shell quantum dot embedded in various dielectric surrounding matrices

The finite-element method (FEM) and the effective-mass approximation (EMA) were used in this study to evaluate the energy eigenvalues and describe the third-order susceptibility for third harmonic generation (THG) associated with intersubband transition in the core-shell nanodot of a GaAs core surrounded by an AlGaAs shell, embedded with three different dielectric surrounding matrices (DSMs) (PVA, PMMA, and SiO2), taking into account the local field effect caused by a DSM. The results with the geometrical factor (shell thickness sk, ellipticity degree & xi;) influencing the electron-wave functions and impurity-energy spectrum, and we compare the optical THG of a single on-center donor impurity core-shell prolate QDs (CSPQDs) embedded in various DSMs. According to our theoretical investigation, in the adequate DSM, the peaks of the real and imaginary parts, as well as the modulus of THG, can be dramatically enhanced and experience a red or blue shift. Furthermore, we observed that increasing the degree of ellipticity of the nanodot results in a radical shift towards a blue-shift with a decrease in the amplitude of the resonance peaks for a silica dielectric matrix. Furthermore, we can see that the presence of donor impurities influences the type of intersubband transition for the same DSM. Such research works on nonlinear optical processes in core-shell nanostructures could've been considered for use in optical nonlinearity-based optoelectronic devices, which operates in different detection domains depending on the dielectric constant, which is affected by the DSM.

Automated summary

The finite-element method (FEM) and the effective-mass approximation (EMA) were used to study the third harmonic generation (THG) in the core-shell nanodot of a GaAs core surrounded by an AlGaAs shell, embedded with different dielectric surrounding matrices (DSMs). The results showed that the real and imaginary parts, as well as the modulus of THG, can be enhanced and experience a shift in the presence of an adequate DSM. Additionally, varying the degree of ellipticity of the nanodot and the presence of donor impurities can also affect the THG.