Numerical Investigation of Enhanced and Quenched Radiative Decay Rate for One and Multiple Emitters near a Nanoparticle Surface

Abstract

In the previous studies, Zhou et al. showed that the enhancement factor of the radiative decay rate of multiple emitters could be significantly smaller than that of one emitter near a silver nanoparticle surface at around its resonance wavelength. An asymmetric line shape was obtained in the enhancement factor spectrum when six or more emitters were included. Using a nanoparticle composed of silver, gold, glass, or materials with artificially defined real (n) and imaginary (k) parts of the index of refraction, we demonstrated that the enhancement factor of the radiative decay rate of six emitters near the nanoparticle surface will be smaller than that of one emitter when the localized surface plasmon resonance is excited. The asymmetric line shape of the enhancement factors for six emitters is affected by both the real and imaginary parts of the indices of refraction of the nanoparticle, and the asymmetric line shape will appear only when the real part (n) of the index of refraction of the nanoparticle is less than that of the environmental medium. The simulations show that a resonance peak in the enhancement spectrum of six emitters will be obtained when the induced electric field inside the particle is antiparallel to the incident polarization direction, whereas a resonance dip appears at wavelengths when the induced electric field inside the nanoparticle is parallel to the incident polarization direction. While the studies explained key parameters affecting the enhancement factor of the radiative decay rate of one and multiple emitters, developing analytical model is still necessary to reveal more physical insight behind the obtained numerical results.

Combined effects of emitter–emitter and emitter–plasmonic surface separations dictate photoluminescence enhancement in a plasmonic field

“…Our theoretical results are also consistent with recent electrodynamics calculations on the effects of multiple point dipoles around metal NPs that have seen, as N is increased, plateauing and relatively small fluorescence enhancements in the N = 6-10 range. 44,80 Reinterpreted in terms of the average nearest QD separations, s, we can say that F em will be flat at low s values and then increase with increasing s, which is qualitatively consistent with our experiments. Keeping in mind that F ex is about a factor of two larger for t = 1.35 nm than t = 5.6 nm we conclude that at low N the overall enhancement factor, eqn (3), will be larger for the t = 1.35 nm case, which is again qualitatively consistent with the experiment (Fig.…”

Effects of Near- and Far-Field Coupling on the Enhancement Factor of the Radiative Decay Rate of Multiple Emitters Near a Silver Nanoparticle Sphere

“…However, when other shaped metal nanoparticles are used, the proportional relationship between the enhanced local electric field and the enhancement factor cannot be guaranteed . When multiple emitters are placed near a metal nanoparticle surface, the relationship between the two is completely broken, , and we cannot use the enhanced local electric field to predict the enhancement factor anymore. Alternatively, we need to use other approaches, like coupled dipole method, to calculate the enhanced radiative decay rate of emitters. ,, …”

“…When multiple emitters are placed near a metal nanoparticle surface, the relationship between the two is completely broken, , and we cannot use the enhanced local electric field to predict the enhancement factor anymore. Alternatively, we need to use other approaches, like coupled dipole method, to calculate the enhanced radiative decay rate of emitters. ,, …”

“…Using the T-matrix method, , Zhou et al examined the enhancement factors of the radiative decay rate of multiple emitters near a silver nanoparticle surface and found that the enhancement factor of multiple emitters drops dramatically in comparison to that of a single emitter. Wang et al systematically studied the enhancement factor change of the radiative decay rate of emitters when one or multiple of them are placed near a nanoparticle with an artificially defined index of refraction. They found that the real and imaginary parts of the index of refraction of the nanoparticle were equally important.…”

“…Using the coupled dipole method, we numerically examined the effects of coupling among multiple emitters and between emitters and metal nanoparticles on the enhancement factor of their radiative decay rate. The study is a continuous effort following the previous two papers, , where the phenomena at different conditions were reported; however, the detailed mechanism was not clearly explained. The simulation results show that the dramatic change of the enhancement factor of the radiative decay rate of multiple emitters in comparison to that of one emitter is due to the near-field coupling among emitters as well as the constructive and destructive far-field coupling between dipoles of emitters and the induced dipole of the metal nanoparticle.…”