Metamaterials are artificially crafted composite materials whose optical functionalities come from patterns or microstructures on their surface. Unfortunately, the design and fabrication of these microstructures still require an extremely time-consuming process.
A research team, led by Distinguished Professor Dai-Sik Kim in the Department of Physics at UNIST has introduced mechanically closable nanotrenches enabling topology changes of metamaterials, thereby switching optical functionalities in a repeatable manner.
In this study, the research team realized mechanically closable nanotrenches for active electromagnetic wave control over broad spectral ranges. Their findings also showed that the fully closable nanotrenches can be embedded in metamaterials of various designs in a predefined and scalable manner. In addition, they identified the deformation mechanics during a closing operation and explained the electromagnetic wave modulation in the visible-NIR regime and the terahertz regime. Because a closable nanotrench enables mechanical control over topology, it will find many applications requiring nonlinear switching of metamaterial multifunctionalities, noted the research team.
Metamaterials that applied this technology were able to control light-specific characteristics such as frequency, intensity, phase (shape of wave), and polarization of electromagnetic waves (visible light, terahertz wave, millimeter wave, etc.) in various wavelength areas. Experiments have also shown that resonance frequencies have more than doubled in most areas, including visible light, and that the intensity of light can be adjusted by more than 99.9% in the Terahertz area, which is considered to be a 6G communication frequency. It could also control both polarization and phase of light.
This study was made available online in March 2021 ahead of final publication in Nano Letters in May 2021.This study has been carried out jointly by Seoul National University, Incheon National University, and Seoul National University of Science and Technology with the support of the National Research Foundation of Korea (NRF).
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Nano Letters