Control of Plasmonic Superradiance in Metallic Nanoparticle Assembly by Light-Induced Force and Fluctuations

The possibility of simultaneous control of the configuration and optical functions of a metallic nanoparticle (NP) assembly by light-induced force (LIF) and thermal fluctuations has been demonstrated on the basis of self-consistent theory of LIF and nonequilibrium dynamics. It has been clarified that the NPs are arranged parallel to the polarization of the focused laser beam under the balance of LIF and the electrostatic repulsive force due to the ions on the surface of NPs. Particularly, in such a NP assembly consisting of high-density NPs, the light-scattering rate (radiative decay) of localized surface plasmon polaritons (LSPPs) can be drastically enhanced to be greater than 100 meV (10 times that of single NPs), and the spectral width is also greatly broadened due to the superradiance effect. The results will provide a foundation of the principles for designing a NP assembly with controllable light scattering for highly efficient broad-band light energy conversion devices.