Enhanced second harmonic generation from a hybrid nanosystem consisting of a semiconductor quantum dot in the presence of two spheroidal plasmonic nanoparticles

In this study, the nonlinear optical process of second harmonic generation from a hybrid nanosystem (also known as a heterotrimer system) composed of two metallic nanoparticles with an ellipsoidal shape and mediated by a semiconductor quantum dot is theoretically studied when the system is subjected to an applied laser electric field as a probe field to produce the two-photon absorption in the semiconductor quantum dot that is responsible for the second-order nonlinear process. In addition to the probe laser field, a control field is applied to the system for optically monitoring the second harmonic signal. The dynamic of the hybrid system is investigated using the master equation of the density matrix of the quantum dot in the presence of two plasmonic nanoparticles under the rotating wave approximation. We demonstrate the tunability of the second harmonic signal from this system due to the dipole-dipole coupling between the semiconductor quantum dot and the metal nanoparticles, which forms a noncentrosymmetric system and enables the second harmonic process. The generation of second harmonic radiation is a nonlinear optical process sensitive to the system's geometry. The impact of the probe laser field, the control field, the dielectric constant of the embedding medium, and the separation distance between the quantum dot and plasmonic nanoparticles on the intensity of the second harmonic signal is demonstrated and discussed.

Automated summary

This study theoretically investigates the second harmonic generation in a hybrid nanosystem composed of two metallic nanoparticles and a semiconductor quantum dot. The system is subjected to a laser electric field as a probe field to produce two-photon absorption in the quantum dot, responsible for the second-order nonlinear process. The impact of various factors on the intensity of the second harmonic signal, including the probe laser field, the control field, the embedding medium's dielectric constant, and the separation distance between the quantum dot and nanoparticles, is demonstrated and discussed.