All-optical reconfigurable chiral meta-molecules

Abstract

Chirality is a ubiquitous phenomenon in the natural world. Many biomolecules without inversion symmetry such as amino acids and sugars are chiral molecules. Measuring and controlling molecular chirality at a high precision down to the atomic scale are highly desired in physics, chemistry, biology, and medicine, however, have remained challenging. Herein, we achieve alloptical reconfigurable chiral meta-molecules experimentally using metallic and dielectric colloidal particles as artificial atoms or building blocks to serve at least two purposes. One is that the ondemand meta-molecules with strongly enhanced optical chirality are well-suited as substrates for surface-enhanced chiroptical spectroscopy of chiral molecules and as active components in optofluidic and nanophotonic devices. The other is that the bottom-up-assembled colloidal metamolecules provide microscopic models to better understand the origin of chirality in the actual atomic and molecular systems.

Three‐dimensional Random Dielectric Colloid Metamaterial with Giant Isotropic Optical Activity

“…This is in strong contrast with the previous designs of dielectric chiral metamaterials and colloids which either suffered from low writing speeds [77] or were suitable only for low colloid concentrations (such colloids were achieved by dispersing nanoparticles from a 2D area into a bulk solution). [33,34,78] The chirality can be further increased by optimizing the geometry of the meta-atoms using, for example, via inverse design. [79] It should be mentioned that although in this work, we concentrated on sub-wavelength dielectric meta-atoms, it is possible to extend this study toward meta-atoms of larger sizes.…”

Reconfigurable Plasmonic Chirality: Fundamentals and Applications

“…[5] Second, we take a number of differently sized plasmonic spheres, which can be freely arranged, e.g., by opto-thermo electric fields. [6] Here one can, on a single structure level, freely rearrange the geometry and thus fully flip the handedness of the structure, giving rise to inverted far-field chiroptical responses as well.…”

“…Alternatively, Lin and co-workers arranged individual colloidal metallic and dielectric nanoparticles on a substrate surface via opto-thermoelectric fields generated by a focused laser beam. [6] This allowed to assemble and disassemble a cluster composed of three differently sized nanoparticles into chiral geometries with intended handedness as sketched in Figure 2d. Rearrangement of the particles could transform the cluster into its enantiomer as well as to varied geometries of the same or opposite handedness.…”

Digital Assembly of Colloidal Particles for Nanoscale Manufacturing

“…c) Schematic and optical images of left‐handed and right‐handed Au chiral trimer along with its differential scattering spectra. Adapted with permission . Copyright 2019, Elsevier Ltd. d) Top: schematic of a microfluidic chip for fabrication of Ag rings in the channel using BP.…”

“…OTA and printing is emerging as an important nanomanufacturing technique that can work with nanoparticles of diverse compositions, which have been out of reach in optical‐tweezers‐based manufacturing. One application where OTA was shown to be of great advantage was the fabrication of chiral meta‐molecules using metallic and dielectric colloidal particles as artificial atoms or building blocks . Measuring and controlling molecular chirality with high precision down to the atomic scale remains challenging.…”