Propagation mechanism of surface-enhanced resonant Raman scattering light through one-dimensional plasmonic hotspot along silver nanowire dimer junction

TL;DR

This study explores how resonant Raman scattering light propagates along a silver nanowire dimer junction, revealing polarization-dependent behavior, spectral shifts, and a detailed mechanism involving localized plasmon and junction surface plasmon modes.

Contribution

It provides a comprehensive understanding of the propagation mechanism of SERRS light in one-dimensional plasmonic hotspots, supported by numerical electromagnetism calculations.

Findings

Propagation depends on excitation and detection polarization.

Spectral redshifts occur at the edges of the hotspot.

Propagation lengths vary significantly between nanowire dimers.

Abstract

We investigate the propagation of surface-enhanced resonant Raman scattering (SERRS) light by several micrometers through a one-dimensional hotspot (1D HS) located between a plasmonic nanowire dimer (NWD). The propagation exhibits the properties, e.g. an effective propagation induced by excitation and detection polarization orthogonal to the 1D HS long axis, the propagation profiles composed of bright short and dark long propagations, SERRS spectral shapes independent of localized plasmon (LP) resonance of NWDs, redshifts in the SERRS spectra at the edges of 1D HSs, and considerable NWD-by-NWD variations in the propagation lengths. These properties are well reproduced by numerical calculations based on electromagnetism. These calculations reveals the following propagation mechanism: excitation light resonantly coupled with LP at the edges of 1D HSs, and the light energy is transferred to two types of junction SP modes supporting the short and long propagations; these modes are attributed to the upper and lower branches of coupled two SP modes. This mechanism comprehensively clarifies the abovementioned properties.