Manipulation of Plasmon Dephasing Time in Nanostructure Arrays Via the Far-Field Coupling.

On-demand manipulation of the plasmon dephasing time plays critical roles in many important applications of localized surface plasmon resonance. Here, we systemically investigate the influence of the far-field coupling on plasmon dephasing time in different nanostructure arrays supporting single or multiple modes by for the first time applying the harmonic oscillator analysis model combined with the finite-difference time-domain numerical simulation. The results show that the dephasing time of a bright mode in the nanodisk array can be well on-demand manipulated based on the far-field coupling through varying the individual nanodisk size and array period. In particular, the dephasing time of nanodisk array with adjusting periods exhibits the behavior of first increasing and then decreasing, and it is also modified to different extents under different nanodisk sizes. Furthermore, for the heptamer array supporting multiple modes, we demonstrate that the influence of array period on dephasing time also exists for a bright mode, but a negligible effect appears for dark mode due to the negligible far-field coupling. These findings provide a potential solution to manipulate the dephasing time of plasmonic nanostructure and thereby offer flexible controllability of the ultrafast on-off process of plasmonic switching and photocatalytic efficiency. [ABSTRACT FROM AUTHOR]