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Proceedings Paper

Thermoelectricity-driven nanotweezers for reconfigurable assembly of chiral meta-molecules (Conference Presentation)
Author(s): Linhan Lin

Paper Abstract

Chirality is a ubiquitous phenomenon in nature, which describes an object that is non-superimposable to its mirror image. A lot of organic molecules, such as amino acids and sugars, are chiral. Mimicking atoms with colloidal nanoparticles owning intriguing optical properties (termed as meta-atoms), the manipulation and organization of colloidal nanoparticles into artificial chiral metamaterials allows the understanding of the origin of chirality at colloidal scale as well as the exploration of new functionality in photonic devices. Herein, we develop an all-optical technique to assemble chiral meta-molecules into arbitrary two-dimensional geometries and to detect their optical chirality in-situ. Taking advantage of the thermophoretic migration of ions under the external temperature field, we generate a light-controlled thermoelectric field to capture and confine colloidal particles at the laser spots, which is termed opto-thermoelectric nanotweezers. Exploring depletion attraction interaction as the interparticle bonding force, we further demonstrate the assembly of colloidal particles of different materials and sizes into chiral meta-molecules. Dark-field spectroscopy is incorporated into the system to detect the scattering intensity of the meta-molecules at different circular polarizations and characterization of the circular dichroism. Specifically, the optical control of the thermoelectric field allows the dis-assembly and re-organization of the chiral meta-molecules into their enantiomers and diastereomers. With its all-optical control, reconfigurability, and versatility, the chiral-metamolecules will finds applications in both optofluidic and nanophotonic devices.

Paper Details

Date Published: 9 September 2019
Proc. SPIE 11083, Optical Trapping and Optical Micromanipulation XVI, 110832I (9 September 2019); doi: 10.1117/12.2531428
Show Author Affiliations
Linhan Lin, The Univ. of Texas at Austin (United States)

Published in SPIE Proceedings Vol. 11083:
Optical Trapping and Optical Micromanipulation XVI
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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