Manipulation of Plasmon Dephasing Time Via the Coupling between Localized Surface Plasmon Resonance and Waveguide Modes

Abstract

Manipulation of plasmon dephasing time of the hybrid modes has gained much attention in recent years, which plays critical roles in many important applications of plasmonics. Here, we manipulate the dephasing time of plasmonic field resulting from coupling of the localized surface plasmon (LSP) of the nanosphere array and the waveguide mode supported by the indium tin oxide film with quasi-normal mode-assisted harmonic oscillator model method. It results in the formation of two distinct plasmonic modes, transverse electric (TE) and transverse magnetic (TM) modes. Such coupling can significantly modify the dynamics of the original plasmonic modes. The dephasing time of the hybrid plasmon modes, encompassing both TE and TM modes, can be extended from 1.25fs to 4.95fs, which is about 2-7 times compared to that of a single localized surface plasmon resonant mode. Notably, the dephasing time of LSP coupled with the TE mode consistently longer than that of the TM mode, which would be attributed to the reduced nonradiative damping. More importantly, by changing the structural parameters, we can flexibly manipulate either the dephasing time with a fixed wavelength or the resonant wavelength with a fixed dephasing time.

Keywords: Localized surface plasmon resonance, Dephasing time, Waveguide modes, Hybrid plasmon modes