Electromagnetic chirality: From fundamentals to nontraditional chiroptical phenomena

September 02, 2020

Recent advancements in artificial nanomaterials and structured optical fields have expanded the concept of chiroptical phenomena. However, chiroptical phenomena originate from complicated processes involving transitions between states with opposite parities, so fundamentals of chiroptical processes are required for solid interpretation the phenomena. Here, theoretical frameworks on chiroptical properties of electromagnetic materials are discussed in the context of microscopic (discrete chiroptical scatterers) and macroscopic (continuous chiroptical media) systems.

"Chiral object refers to a three-dimensional object that cannot be superimposed onto its mirror image using only translations and rotations. Such chiral objects interact differently with left- and right-circularly polarized lights, and absorption difference at these two circular polarizations (circular dichroism) has been widely used to characterize chiroptical properties of the chiral objects. However, (geometric) chirality is a qualitative property; that is, we do not say one's hand is more chiral than another's hand. On the other hand, observed chiroptical effects are measurable quantities. By introducing chiroptical parameters, the chiroptical effects can be described and the degree of electromagnetic chirality can be defined and quantified."

Additionally, chiroptical properties of electromagnetic fields are discussed in the context of local density of field chirality and its flux, which have been defined as the optical chirality and optical helicity. Also, helical beams with intrinsic orbital angular momentum are discussed as another class of chiral light.

"Generally speaking, a chiral phenomenon involves two chiral objects, where one chiral object differently interacts with another chiral object and its enantiomer (mirror image). In chiroptical phenomena, one of the chiral objects is the light itself. By recognizing that light can also be chiral, the degree of chirality of the field can also be quantified."

Several chiroptical phenomena are discussed under the framework of using the identical chiroptical parameters of the fields and materials. This approach provides a clear understanding of several chiroptical phenomena including intrinsic and extrinsic chirality, enantioselective scattering, molecular sensing, and optomechanical effects. This review paper will be helpful to understand complicated chiroptical phenomena and for designing and optimizing chiroptical systems and fields with well-defined figure of merit.
-end-


Light Publishing Center, Changchun Institute of Optics, Fine Mechanics And Physics, Chinese Academy

Related Electromagnetic Fields Articles from Brightsurf:

Sheer protection from electromagnetic radiation
A printable ink that is both conductive and transparent can also block radio waves.

Remote control of blood sugar: Electromagnetic fields treat diabetes in animal models
Researchers at the University of Iowa may have discovered a safe new way to manage blood sugar non-invasively.

Could megatesla magnetic fields be realized on Earth?
A team of researchers led by Osaka University discovered a novel mechanism called a ''microtube implosion,'' demonstrating the generation of megatesla-order magnetic fields, which is three orders of magnitude higher than those ever experimentally achieved.

Electromagnetic chirality: From fundamentals to nontraditional chiroptical phenomena
Theoretical frameworks of chiroptical properties of electromagnetic materials and fields are reviewed.

A new way to fabricate MXene films that block electromagnetic interference
A multi-institution research team led by Andre ? D. Taylor, professor of chemical and biomolecular engineering at the NYU Tandon School of Engineering demonstrated a novel approach to MXene fabrication that could lead to methods for at-scale production of MXene freestanding films: drop-casting onto prepatterned hydrophobic substrates.

A new MXene material shows extraordinary electromagnetic interference shielding ability
Researchers from Drexel University and the Korea Institute of Science and Technology have discovered a MXene material that presents exceptional electromagnetic interference shielding abilities.

Underused part of the electromagnetic spectrum gets optics boost from metamaterial
Terahertz radiation, or T-rays, has barely been exploited compared to most of the rest of the electromagnetic spectrum.

New handle for controlling electromagnetic properties could enable spintronic computing
Materials scientists at Duke University have shown the first clear example that a material's transition into a magnet can control instabilities in its crystalline structure that cause it to change from a conductor to an insulator.

Torquato research links elastodynamic and electromagnetic wave phenomena
Princeton's Salvatore Torquato, the Lewis Bernard Professor of Natural Sciences and director of the Complex Materials Theory Group, published research this week in the Proceedings of the National Academy of Sciences (PNAS) linking wave phenomena that has never previously been linked.

Updated guidelines for exposure to high-frequency electromagnetic fields published in Health Physics
A set of updated, evidence-based guidelines defining safe levels of exposure to high-frequency electromagnetic fields (EMF) has been published in Health Physics, official journal of the Health Physics Society.

Read More: Electromagnetic Fields News and Electromagnetic Fields Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.