Plasmon enhanced optical Kerr susceptibility of quantum dots

Abstract

A significant gain in optical Kerr susceptibility of semiconductor quantum systems is of great importance for enabling nonlinear optical devices for the applications such as optical switches and high-density on-chip integration. Here, we investigate the optical Kerr susceptibility of the semiconductor quantum dot in the hybrid structure consisting of a semiconductor quantum dot and a metal nanoparticle. Taking into account the exciton-plasmon coupling, the modified expression for the optical Kerr susceptibility of the semiconductor quantum dot in the hybrid structure is given using iterative method and density matrix theory. One finds that the optical Kerr susceptibility of the semiconductor quantum dot in the hybrid structure is one to two orders of magnitude larger than that of an isolated semiconductor quantum dot. The magnitude of such enhancement is strongly dependent on the surrounding dielectric environment. Furthermore, the magnitude of the optical Kerr susceptibility of the semiconductor quantum dot in the hybrid structure exhibits a decrease followed by an increase with the increase of the radius of the semiconductor quantum dot, while that produced by the isolated semiconductor quantum dot demonstrates an increase. Such non-monotonic dependence makes the hybrid structure a promising candidate for developing nonlinear optical nano-devices with good performances.