Shell-induced modification of plasmon coupling and appearance of fano resonance without symmetry breaking in core/shell heteronanostructures

Abstract

Simulations based on the Discrete Dipole Approximation (DDA) method have been conducted to construct theoretical models consisting of gold cores embedded with various materials in multi-nanoshells, aiming to investigate their plasmonic properties. The optical response of core/multi-shell systems to incident waves is significantly enhanced, with nanoshells demonstrated to effectively modulate surface plasmon frequencies. The plasmon frequencies of shells can be adjusted to match the resonance frequency of the core. The presence of shells alters the field distribution of the entire system, resulting in oscillations perpendicular to the incident polarization. The complex field distribution induced by shells supports the possibility of creating dark resonance modes, leading to predominantly dipolar resonance fano-like resonances combined with bright resonance modes. Core/multi-shell systems have been shown to support fano-like resonances without the need to break symmetry. Strong localized optical fields can be achieved at the frequency of Fano resonance. The narrow spectral features and high local fields of Fano resonances enable many applications based on surface plasmon properties. Simulations and studies have also been conducted on Au/Au core/multi-shell systems with cavity support materials. Rich plasmonic properties can be obtained at their interfaces due to the unique electronic properties of different materials. Different plasmonic phenomena have been observed for the same materials with different structures. In this paper, we only use the gold core/shell to carry out the research.