Finite-difference methods used to model photonic wave localization in 3D quasicrystals
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ference methods used to model photonic wave localization in 3D quasicrystals
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cientists at the Korea Institute of Science and Technology (KIST), led by Kayhun Hur, have made the first theoretical demonstration of the localization of photonic waves in a three-dimensional (3D) quasicrystal. This promising finding suggests that quasicrystals could one day be precisely engineered to control localization of electrons, phonons, and photons.
Schematic representation of photonic wave localization in a three-dimensional icosahedral quasicrystal. Incident photonic waves are trapped in the quasicrystal due to localization. Image courtesy of Kahyun Hur, Korea Institute of Science and Technology.
The researchers theorize that perhaps the high pressure causes some slight modification of the structure that makes the material stable at ambient pressure as well. Separating ethanol from water is a key issue in biofuel production, so this zeolite might have a practical application. Tabacchi envisions trying more complex systems with a different zeolite to accommodate molecules of larger size, like the chromophores of a dye, to create a material featuring a 2D arrangement of photoactive molecules that perhaps can capture solar energy more efficiently than is now possible.
“Beautiful and fascinating” is how Gion Calzaferri, a professor in the Department of Chemistry and Biochemistry at the University of Bern, Switzerland, who was not involved in this research, describes the work. “The discovery of this host–guest composite allows us to dream about materials having fascinating physical (and perhaps also chemical) properties we have not seen so far. It may be the beginning of a new area of research exploring onedimensional nanomaterials based on two different parallel running molecular wires.” Tim Palucka
Quasicrystals are a unique type of crystalline material with local order but no long-range periodicity. The discovery of these materials in aluminum-manganese alloys garnered materials scientist Dan Shechtman the 2011 Nobel Prize in Chemistry. Quasicrystals exhibit unusual properties due to their mixed structural characteristics. Because translational symmetry strongly governs the transport properties of every form of wave, wave transport in quasicrystals—including localization—has been a long-standing area of research interest. In particular, icosahedral quasicrystals possess a 3D photonic bandgap, which could allow for control of light at the nanoscale. In crystalline materials, waves with wavelengths commensurate with the crystal’s periodicity can transmit without scattering loss, leading to ballistic transmission. In contrast, because of frequent scattering, wave transport in disordered materials is usually described by random walks, resulting in diffusive transmission. Quasicrystals exhibit both diffusive transport due to their aperiodicity, along with a well-defined coherent path due to their crystalline nature. These materials therefore provide a compelling test system to investigate wave localization in three dimensions. As
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