Transient Study of Photoluminescence in Nanowaveguides Doped with Quantum Emitters and Metallic Nanoparticles.

Abstract

We have studied the time-dependent optical properties of nanowaveguides containing an ensemble of noninteracting quantum emitters and interaction metallic nanoparticles. We have developed a theory for transient photoluminescence (PL) and exciton population density using the density matrix method. In our theory, we have included the effect of the dipole-dipole interaction (DDI) between metallic nanoparticles along with the effect of the surface plasmon polaritons (SPPs) created by metallic nanoparticles. We compared our theory with the transient PL experiments of nanohybrids fabricated from CdSe/ZnS quantum dots and an Ag nanorod array. A good agreement between theory and PL experiment is found. We have also examined the transient behavior of the photoluminescence in the presence of the DDI and SPP couplings. It is observed that the number of transient PL oscillations increases as the DDI coupling increases. The width of the transient peaks also increases as the amount of the DDI coupling increases. Finally, we predicted that the peaks of the transient PL oscillation split from one peak to two peaks as the intensity of the DDI coupling reaches the strong coupling limit. The strong coupling limit is defined when the DDI coupling is larger than the PL decay rates. This finding can be used to fabricate nano switches by using one peak as the OFF position and two peaks as the ON position. The above findings also suggest the transient plasmonic properties of nanowaveguides can be controlled by the SPP and DDI couplings. These findings have potential applications in the development of transient nanoscale plasmonic devices such as nano detectors and optical nano switches.