  Topological plasmonic provides a new insight for the manipulation of light.
Analogous to exotic nature of topological edge states in topological photonics,
topological plasmonic combines concepts from topology and plasmonics. By
utilizing topological protection, plasmons can be made to propagate without
significant scattering or decay, even in the presence of defects or disorder.
Herein, we present a study on the design, characterization, and manipulation of
topological plasmonic chains of discs based on the Su-Schrieffer-Heeger model
made into a ring resonator. The investigation focuses on exploring the unique
properties of these resonators and their potential to support topologically
protected edge modes, within the continuum of rotationally symmetric optical
modes of a ring. To observe the topological edge modes in rotationally
symmetric chains, we employ a symmetry-breaking excitation technique based on
electron beams. It analyzes the influence of parameters such as dimerization
and loop numbers on the presence of topological modes. Additionally, we explore
the manipulation of electron impact positions to control the direction of
propagation and selectively excite specific bulk or edge modes. The findings
contribute to a deeper understanding of topological effects by numerically
investigating their design principles and exploring techniques to manipulate
topological edge modes. The insights gained from this study have implications
for the development of nanoscale plasmonic systems with customized
functionalities, potentially impacting areas such as nanophotonics and quantum
information processing.
