| Description |
Active plasmonic and active chiral plasmonic systems represent burgeoning, yet challenging, subfields within plasmonics that potentially offer tailorable responsivity regarding light manipulation. By exploiting light-matter orientation-dependencies (an aspect of polarization-based optics), both active plasmonic and active chiral plasmonic properties are illustrated using an exemplary anisotropic nanostructure array. The control of plasmon activity is evaluated showing that optical extinction intensities range between ±20% to ±36%, which also includes controlled switches in chiroptical handedness on par in magnitude with archetypal intrinsically (or structurally) chiral plasmonic nanostructures. Modeling of peak LSPR optical extinction profiles reveals dramatic sensitivity toward magnetoelectric dipolar and multipolar coupling interactions attributed to incident electromagnetic field components and gradients-the underlying cause for these active plasmonic light-matter orientation-dependent properties. The chiroptical properties of a plasmonic material are also dependent on its design due to structural and orientation-dependent behavior of plasmon modes. Understanding light-matter interactions in plasmonics can lead to the discovery of new physical phenomena and potentially offers approaches to manipulate these interactions. Therefore, identifying the origin of optical chirality is an important goal in realizing plasmonic nanomaterial potential. Presented in this work, an extensive characterization of the spatial arrangement of the incident light and the nanostructures permits a more comprehensive iv insight towards the origin of chiroptical responsiveness pertaining to a plasmonic dimer nanostructure. These Au dimer nanocrescents are fabricated in the same fashion as single nanocrescents and represent a partial bilayer unit cell configuration offering interparticle plasmonic coupling. This configuration results in the novel expression of latent plasmonic chirality, which is the simultaneous expression of true and birefringent circular dichroism handedness. The reported optical behavior for Au dimer nanocrescents offers insights into compelling design strategies towards developing advanced, orientation-dependent optical materials based on the concepts of plasmonic and structural chirality. A novel approach to fabricate controlled geometric asymmetry into nanocrescent-like structures is also presented. These asymmetric dimer nanocrescents exhibit a partial layered configuration as observed in symmetric dimer nanocrescents. The layer separating nanocrescent tips in these asymmetric dimer nanocrescents is controlled via fabrication and the chiroptical behavior of these enantiomorphic sets differ dramatically. |
