The Beginner's Guide to Chiral Plasmonics: Mostly Harmless Theory and the Design of Large‐Area Substrates

Abstract

Plasmonic effects in noble metal nanostructures are probably one of the most widely recognized forms of nanotechnology. The tremendous success and interdisciplinary use of plasmonic Chiral plasmonics is a fascinating research field that is attractive to scientists from diverse backgrounds. Physicists study light-matter interactions, chemists seek ways to analyze enantiomeric molecules, biologists study living objects, and material engineers focus on scalable production processes. Successful access to this emergent field for an interdisciplinary community depends on overcoming three main issues. First, understanding the physical background of chiral plasmonics requires proper introduction in easy language. Second, pitfalls in the characterization of chiroplasmonic features can prevent accurate interpretation. Third, simple and robust methods capable of covering macroscopic substrate areas must be available. This tutorial-style review addresses these issues with the goal to provide a comprehensive introduction into chiral plasmonic nanostructures. It starts with a brief introduction of the relevant physics involved in chiral light−matter interactions. A brief guide about how to adequately characterize samples follows. Subsequently, an overview of fabrication techniques that produce chiral substrates over large areas is given, and the strengths and weaknesses of the different approaches are discussed. The focus is on simple and robust processes that do not require clean room facilities and can be implemented by a much larger scientific audience.

Engineering Strongly Chiral Plasmonic Lattices with Achiral Unit Cells for Sensing and Photodetection

“…Importantly, a 2D chiral structure in a nonhomogeneous medium has no mirror symmetry with respect to the horizontal plane and is thus fully 3D chiral. [ 16,66 ] Overall, we summarize that our lattices possess optical chirality for the directional transmittance for both homogeneous and heterogeneous environments, and the heterogeneous system shows typically larger peak values for .…”

“…Over the last years, spirals, [ 5 ] helices, [ 6–8 ] twisted nanorods, [ 9,10 ] helicuboids, [ 11 ] and chiral assemblies of achiral nanoobjects [ 12–15 ] have been engineered and studied; one can see more examples in recent reviews. [ 16–18 ] These chiral materials can be used as circular polarizers, [ 8 ] polarization‐sensitive photodetectors, [ 19,20 ] and photocatalysts. [ 6,10 ]…”

“…Over the last years, spirals, [5] helices, [6][7][8] twisted nanorods, [9,10] helicuboids, [11] and chiral assemblies of achiral nanoobjects [12][13][14][15] have been engineered and studied; one can see more examples in recent reviews. [16][17][18] These chiral materials can be used as circular polarizers, [8] polarization-sensitive photodetectors, [19,20] and photocatalysts. [6,10] Along with single chiral nanocrystals and assemblies, the field of chiral nanooptics covers the study of periodic 2D arrays of nanoobjects with strong optical chirality.…”

Template-assisted self-assembly of achiral plasmonic nanoparticles into chiral structures

“… 69 It should be mentioned that such periodic arrays can show system chirality as an extrinsic property for tilted light incidence. 70 This type of optical activity is a consequence of symmetry reduction for a specific pattern orientation. Notwithstanding, if plasmonic particles with intrinsic chirality can be used as the repeating units, lattice resonances could be obtained that are chiral in nature.…”

Chiral Plasmonic Ellipsoids: An Extended Mie–Gans Model

“…An exact mathematical characterization of these structures is imperative to harness their full potential. Although theories of chiral molecules are established, theories governing metal nanoparticle assemblies, − quantum dots, − and metal nanoclusters , are still in development.…”