Switching and Sensing Using Kerr Nonlinearity in Quantum Dots Doped in Metallic Nanoshells
Mahi R. Singh, S. G. Yastrebov
Abstract
A theory of a switching and sensing mechanisms using the Kerr nonlinearity has been developed for nanohybrids made of an ensemble of three-level quantum emitters and metallic nanoshells. We have calculated the surface plasmon polaritons at interface between the metallic core and dielectric shell of the metallic nanoshell. The Kerr nonlinearity has been calculated by using the quantum density matrix method in the dipole–dipole coupling between quantum emitters. We showed that the switching and sensing mechanisms due to the Kerr nonlinearity are made of four contributions. The first contribution is due to three probe photons and the second one is due to one polariton and two probe photons. On other hand, the third contribution is due to the two polaritons and one probe photon, and the fourth one is due to three polaritons. The enhancement in the Kerr nonlinearity is found, and it is due to second, third, and fourth contributions. This prediction can be used to fabricate all optical Kerr nanosensors. It is also shown that two peaks (ON) in the Kerr coefficient can be switched to four peaks (OFF) due to the strong dipole–dipole coupling. We have also predicted that the Kerr coefficient can be switched from the positive value (ON) to the negative value (OFF) by changing the dipole–dipole coupling. We found that the minimum of the Kerr coefficient changes sign from positive (ON) to negative (OFF) as the dipole–dipole coupling strength increases. The splitting in the Kerr spectrum is due to the presence of the dressed states created in the nanohybrid due the dipole–dipole interaction. These predictions can be used to fabricate all optical Kerr nanoswitches.