Chirality of Symmetric Resonant Heterostructures

Self Cite

Chiral plasmonic nanostructures hold promise for enhanced chiral sensing and circular dichroism spectroscopy of chiral molecules. It is therefore of interest to fabricate chiral plasmonic nanostructures with tailored chiroptical properties over large areas with reasonable effort. Here, a colloidal lithography approach is used to produce macroscopic arrays of sub‐micrometer 3D chiral plasmonic crescent structures over areas >1 cm2. The chirality originates from symmetry breaking by the introduction of a step within the crescent structure. This step is produced by an intermediate layer of silicon dioxide onto which the metal crescent structure is deposited. It is experimentally demonstrated that the chiroptical properties in such structures can be tailored by changing the position of the step within the crescent. These experiments are complemented by finite element simulations and the application of a multipole expansion to elucidate the physical origin of the circular dichroism of the crescent structures.

Section: Resultsmentioning

confidence: 99%

Section: Realization Of Individual 3d Chiral Crescentsmentioning

confidence: 99%

Large‐Area 3D Plasmonic Crescents with Tunable Chirality

Goerlitzer

Mohammadi

Nechayev

et al. 2019

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“…In contrast, truly chiral objects retain their chiroptical response upon flipping the substrate and exhibit chiral responses in a homogenous refractive index (RI) environment. [33,37,52,53,58] Similarly, we can observe that mirror-symmetric objects can resemble (truly) chiral objects if their angle of illumination is oblique, i.e., if the substrate is tilted (Figure 1c, right). This phenomenon is known as extrinsic chirality.…”

Section: What Is Chirality In the Context Of Chiral Optics And Why Does It Mattermentioning

confidence: 76%

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

Goerlitzer

Puri

Moses

et al. 2021

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.

“…To date, several studies [ 5,21–29 ] have confirmed the potential of high refractive index dielectric nanostructures to enhance optical chirality in the near field. The performance of a silicon sphere in optical chirality enhancement was analyzed based on the Mie theory, and it was found that the optical chirality enhancement was always accompanied with magnetic resonances and increased for higher resonance orders.…”

Section: Introductionmentioning

confidence: 99%

“…[ 23 ] Subsequently, studies on the optical chirality properties of nanosphere homo‐ and heterodimers demonstrated that the optical chirality of dielectric dimers was superior to that of metal dimers. [ 21,24–27 ] In addition, metasurfaces composed of high refractive index disks can be structurally designed to achieve large‐volume uniform‐sign optical chirality enhancement by simultaneously manipulating the electric and magnetic resonances, and particularly achieve the best performance at the Kerker condition. [ 5,21,28 ] At the bud of this new trend, it is worth looking into the effects of various modes and multipolar interference in Mie resonators on optical chirality.…”

Section: Introductionmentioning

confidence: 99%

Optical Chirality Enhancement in Hollow Silicon Disk by Dipolar Interference

Wang

et al. 2020

Optical chirality enhancement is highly demanded for enantioselective interaction of circularly polarized light with chiral molecules. The chirality enhancement in the coaxial air hole of a hollow silicon disk depends on three aspects, namely, the enhancements of electric and magnetic fields and a factor determined by the phases of their field components. In the spectral regime of dipole resonances, maximum chirality enhancement with sign consistency and uniform spatial distribution in the air hole can be obtained in association with both magnetic dipole resonance and anapole. Due to dipolar interference, the chirality is nulled at their coincidence, around which the sign of chirality is reversed. Maximum chirality with both positive and negative signs can be found between magnetic dipole resonance and anapole in the vicinity of their coincidence. This situation is maintained under size scaling so that the operation wavelength can be broadly tuned. The optical chirality can be further improved by merely adjusting the hole radius, by which the optimal spatially averaged optical chirality enhancement factor can reach 39 and −23. The simple strategy for optimizing Mie resonators presented in this work may benefit the design of Mie resonator‐based achiral metasurfaces for chirality detection application.