Nonlinear optical rectification, second and third harmonic generation in quantum dot-double quantum rings: electric field and geometry effects

Abstract We theoretically investigated the electronic and nonlinear optical properties of 3D quantum dot-double quantum ring structures of GaAs/Al 0.3 Ga 0.7 As under electric field. We studied four representative geometries with variable dot height and inner ring width, performing full 3D calculations. The nonlinear optical rectification (NOR) is strongly influenced by the structural parameters and increases with the degree of asymmetry induced by the electric field. We found enhanced NOR values especially for the structure with small dot height. Large second harmonic generation (SHG) at the double resonance condition was obtained in all cases at specific values of the electric field. As for NOR, the small dot height structure exhibits the biggest SHG signal at resonance. Significant third harmonic generation (THG) coefficients are obtained only for medium dot height geometry. The stronger THG signal is emitted by the structure with larger inner ring.