Customer Spotlight - Control of Light Transmission in a Plasmonic Liquid Metacrystal

Scientists from the University of Lorraine have demonstrated the control of light transmission through a slab of plasmonic liquid metacrystal by an external electric field.

Nanopartz Nanorods driven to alignment through electric field controlled liquid crystals

Nanopartz Nanorods driven to alignment through electric field controlled liquid crystals

Overview

A liquid metacrystal is an array of anisotropic subwavelength particles suspended in a viscous liquid. Like a regular liquid crystal, such a medium has no spatial order, while the orientational order can be induced by an external static electric field, leading to the appearance of macroscopic anisotropy. At the same time, the particles composing the metacrystal, the so-called meta-atoms, can be designed for resonant response at certain frequencies. By applying the external static field, we were able to induce macroscopic anisotropy, which caused the polarization-dependent suppression of transmission at resonant frequencies. Such behavior indicates the selective plasmon excitation governed by the orientation of the meta-atoms with respect to the polarization of the electromagnetic wave. The problem of light transmission through a plasmonic liquid metacrystal was analyzed theoretically from first principles, and the obtained results were compared with the experimental data.

Problem Addressed

This work is basically a proof-of-principle experimental study supporting the theoretical concept of a liquid metacrystal introduced in previous studies.

Nanorod Polarizer Schematic

Schematic Representation of the experimental setup (from [1])

Solution

The main property of a liquid metacrystal is the strong macroscopic anisotropy induced by an external static electric field, which comes from the anisotropy of each meta-atom. Namely, in the absence of an external field, meta-atoms are oriented randomly, and their macroscopic ensemble is therefore isotropic. However, a static electric field orients the meta-atoms in the same direction, resulting in the appearance of an average anisotropy of such a medium as a whole. To detect such behavior, we studied the influence of the static electric field on the transmission of two orthogonal linear polarizations through an LMC film.

Novelty, Applications, and Future work

We have demonstrated the liquid metacrystal behavior in the visible range. Unlike previously reported microwave- and terahertz-range liquid metacrystals, visible range requires working with nano-scaled objects.

The proposed concept can be potentially used as an optical element with the controllable axis of anisotropy. In addition, it may offer selective polarization-sensitive absorption and strong nonlinearity.

In the future work, we plan to experimentally demonstrate a controllable hyperbolic material based on a liquid metacrystal. Hyperbolic materials are materials with extreme anisotropy, when their permittivity tensor in primary axes has both positive and negative diagonal components. It gives a hyperboloid shape to their dispersion surface, unlike ellipsoid shape in normal materials.

Alignment of gold nanorods through external electric fields

Increasing nanorod alignment through increasing external electric field (from [1])

Nanopartz' Role

Nanopartz provided us with the crucial part of the research, namely, with gold nanorods that were used as the meta-atoms.

Contact and Publication

Alain Celzard is a full professor at the University of Lorraine, head of department at the Institut Jean Lamour (IJL), one of Europe's largest materials science laboratories. He is a specialist in complex and highly disordered materials, their preparation, properties and applications. Vanessa Fierro is research director at the CNRS and team leader at the IJL. She is a specialist in the characterization of porous materials and nanoparticles. Alexander Zharov is a postdoctoral researcher at the Institut Jean Lamour and a research fellow at the Institute for Physics of Microstructures. He is a specialist in electromagnetic metamaterials and plasmonics. George Kenanakis is a principal Researcher at the Institute of Electronic Structure and laser (IESL) of Foundation for Research & Technology - Hellas (FORTH) in Greece. His main research topic are focused on Photonic Metamaterials and Devices, although he has interdisciplinary research interests ranging between applied physics and electromagnetism to chemical synthesis of materials and structural characterization and instrumentation. Zacharias Viskadourakis is a postdoctoral researcher at the Institute of Electronic Structure and laser (IESL) of Foundation for Research & Technology - Hellas (FORTH) in Greece. He is a specialist in the magnetic and electrical characterization of thin films and nanostructures.  

{1] Zharov, A.; Viskadourakis, Z.; Kenanakis, G.; Fierro, V.; Celzard, A. Control of Light Transmission in a Plasmonic Liquid Metacrystal. Nanomaterials 2021, 11, 346. https://doi.org/10.3390/nano11020346

Nanopartz Products Used for this Research

The products used for this research are our Gold Nanorods.