Related Experiment Video
Updated: Jun 16, 2025
08:07
A Micropatterning Assay for Measuring Cell Chirality
Published on: March 11, 2022
2.3K
Extrinsic chirality tailors Stokes parameters in simple asymmetric metasurfaces
Emilija Petronijevic1, Tiziana Cesca2, Carlo Scian2
1Department SBAI, Sapienza University of Roma, Via A. Scarpa 14, I-00161 Rome, Italy. emilija.petronijevic@uniroma1.it.
Nanoscale
|August 20, 2024
Summary
Simple asymmetric metasurfaces control light polarization. These low-cost nanosphere-based devices exhibit tunable circular dichroism (CD) and manipulate Stokes parameters, showing promise for chiral sensing and flat optics applications.
Area of Science:
- Nanophotonics and Plasmonics
- Chiroptical Metasurfaces
- Light-Matter Interactions
Background:
- Metasurfaces enable nanoscale control of electromagnetic waves.
- Asymmetric designs allow differential interaction with left and right circularly polarized light.
- Chiral sensing and flat optics benefit from polarization-dependent light manipulation.
Purpose of the Study:
- To demonstrate simple, low-cost asymmetric metasurfaces for controlling Stokes parameters.
- To investigate the spectral and angular tunability of these metasurfaces.
- To correlate near-field chiral responses with far-field polarization control.
Main Methods:
- Fabrication of asymmetric plasmonic shells on polystyrene nanospheres (50 nm thickness).
- Broadband extrinsic chirality investigation using extinction circular dichroism (CD) measurements.
- Hyperspectral Stokes polarimetry on transmitted light under linear polarization excitation.
- Numerical simulations to analyze near-field chiro-optical effects.
Main Results:
- Achieved high extinction circular dichroism (CD) in the near-infrared.
- Demonstrated control over the S3 Stokes parameter, mirroring CD behavior.
- Showcased wide tunability of the output field's Poincaré sphere position via incidence angle and wavelength.
- Experimental results showed good agreement with simulations.
Conclusions:
- Simple, low-cost asymmetric metasurfaces effectively control transmitted far-field Stokes parameters.
- Tunable extrinsic chirality and polarization control are achievable across spectral and angular ranges.
- Near-field chiro-optical responses are crucial for extrinsic chiral behavior and transmitted polarization states.
Related Concept Videos
02:25Chirality
23.6K
Chirality is a term that describes the lack of mirror symmetry in an object. In other words, chiral objects cannot be superposed on their mirror images. For example, our feet are chiral, as the mirror image of the left foot, the right foot, cannot be superposed on the left foot.
Chiral objects exhibit a sense of handedness when they interact with another chiral object. For example, our left foot can only fit in the left shoe and not in the right shoe. Achiral objects — objects that have...
Chiral objects exhibit a sense of handedness when they interact with another chiral object. For example, our left foot can only fit in the left shoe and not in the right shoe. Achiral objects — objects that have...
23.6K
02:05Prochirality
3.8K
The concept of prochirality leads to the nomenclature of the individual faces of a molecule and plays a crucial role in the enantioselective reaction. It is a concept where two or more achiral molecules react to produce chiral products. A typical process is the reaction of an achiral ketone to generate a chiral alcohol. Here, the achiral reactant reacts with an achiral reducing agent, sodium borohydride, to generate an equimolar mixture of the chiral enantiomers of the product. For example, an...
3.8K
02:24Properties of Enantiomers and Optical Activity
16.8K
It is essential to understand the difference between chiral and achiral interactions and the implications thereof in optical activity and their applications. Just as our feet, which are chiral, interact uniquely with chiral objects, such as a pair of shoes, but identically with achiral socks, enantiomers of a molecule exhibit different properties only when they interact with other chiral media. An example of a significant implication from this facet is the phenomenon known as optical activity,...
16.8K
02:30Chirality in Nature
13.2K
Chirality is the most intriguing yet essential facet of nature, governing life’s biochemical processes and precision. It can be observed from a snail shell pattern in a macroscopic world to an amino acid, the minutest building block of life. Most of the snails around the world have right-coiled shells because of the intrinsic chirality in their genes. All the amino acids present in the human body exist in an enantiomerically pure state, except for glycine - the sole achiral amino acid.
13.2K
02:25Molecules with Multiple Chiral Centers
11.4K
Molecules that possess multiple chiral centers can afford a large number of stereoisomers. For instance, while some molecules like 2-butanol have one chiral center, defined as a tetrahedral carbon atom with four different substituents attached, several molecules like butane-2,3-diol have multiple chiral centers. A simple formula to predict the number of stereoisomers possible for a molecule with n chiral centers is 2n. However, there can be a lower number where some of the stereoisomers are...
11.4K
02:18Fischer Projections
13.1K
Learning to draw Fischer projections of molecules and understanding their relevance plays a crucial role in the visual depiction of organic molecules. A Fischer projection is a two-dimensional projection on a planar surface to simplify the three-dimensional wedge–dash representation of molecules. This is especially helpful in the case of molecules with multiple chiral centers that can be difficult to draw. Here, all the bonds of interest are represented as horizontal or vertical lines.
13.1K