Control of Self-Kerr Nonlinearity in a Driven Coupled Semiconductor Quantum Dot-Metal Nanoparticle Structure

The self-Kerr nonlinear optical response of a probe field is investigated in the presence of a near-resonant pump field in coupled metal nanoparticle (MNP)-semiconductor quantum dot (SQD) nanostructures. The study of the spectra is based on the solution of the resulted density matrix equations for the case of a colloidal CdSe-based SQD-(Au)MNP molecule, as well as for an epitaxial SQD structure coupled to an Au nanoparticle. It is demonstrated that below a critical value of the interparticle distance the susceptibility of each distinct component of the structure exhibits a characteristic single-resonance spectrum, whereas above this value, the spectrum has three resonances. This phenomenon can be understood in terms of the theory of exciton-plasmon quantum metastates. In addition, the conditions under which optical transparency occurs with a concurrent positive self-phase-modulation coefficient are also identified.