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International Center for Materials Nanoarchitectonics (WPI-MANA)

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[[Research Highlights Vol.30] Topological Photonic Crystal Made of Silicon](https://mdr.nims.go.jp/datasets/2e3f3ae3-c960-45d9-9c4c-3c6f3210ac1a)

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2022/04/04 10:11 Topological Photonic Crystal Made of Silicon | MANAhttps://www.nims.go.jp/mana/research/highlights/vol30.html 1/2Previous  Index  NextResearch Highlights[Vol. 30]Topological Photonic Crystal Made of Silicon19 Jan, 2017WPI-MANA researchers derive topological photonic states purely based on silicon, whichcan lead to the development of new functions and devices through integration withsemiconductor electronicsFigure: (Top) Schematic of photonic crystals consisting of nanorods derived fromthe honeycomb lattice viewed from above, and (bottom) the correspondingphotonic bands. Photonic crystals are obtained by dividing the nearestneighboring nanorods into hexagonal clusters, and widening (a) or narrowing (c)the separation between the hexagonal clusters from the original honeycomblattice (b), while maintaining the same shape and size of the hexagons. In (c), aband inversion occurs between the photonic p- and d-bands, which generatestopological features in the system.Topology is a mathematical concept which describes the way of connection of an object invariantunder continuous deformation. Recently, it has been pointed out that topology can also be definedin the electronic states of materials, and this provides a unified and useful picture for physicistsdescribing the unique properties of materials.Based on a new approach which they have dubbed “topological nanoarchitectonics,” Xiao Hu andLong-Hua Wu, who are theoreticians at the International Center for Materials Nanoarchitectonics(MANA), National Institute for Materials Science (NIMS), elucidated a new principle which makeselectromagnetic waves including light propagate on the edge in a two-dimensional photonic crystalwithout being scattered.https://www.nims.go.jp/mana/research/highlights/vol29.htmlhttps://www.nims.go.jp/mana/research/highlights/index.htmlhttps://www.nims.go.jp/mana/research/highlights/vol31.html2022/04/04 10:11 Topological Photonic Crystal Made of Silicon | MANAhttps://www.nims.go.jp/mana/research/highlights/vol30.html 2/2It was known that scattering of light by defects in conventional photonic crystals can besuppressed in topological photonic states, but so far special materials were required in order tocreate topological photonic crystals. However, the MANA researchers discovered a new principlewhich makes it possible to realize a topological photonic crystal by merely adjusting the positionsof insulator or semiconductor nanorods in a honeycomb lattice, without using any special materialor complicated structure. When hexagonal clusters are formed by adjusting the positions ofnanorods, electromagnetic modes carrying spin, which is conventionally specific to electrons,appear. As a result, the MANA researchers theoretically clarified that a photonic crystal exhibitstopological properties when the separation between hexagonal clusters is narrowed from that ofthe honeycomb lattice.Since this new property of a photonic crystal can be obtained even by semiconductor such assilicon and/or GaN alone, various new functions are expected by integration of informationprocessing functions achieved by the well-established semiconductor electronics and the excellenttopological property of electromagnetic waves.Reference"Scheme for Achieving a Topological Photonic Crystal by Using Dielectric Material"Long-Hua Wu and Xiao HuJournal : Phys. Rev. Lett. 114 (2015) 223901.DOI : 10.1103/PhysRevLett.114.223901AffiliationsInternational Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for MaterialsScience (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044, JapanContact informationInternational Center for Materials Nanoarchitectonics(WPI-MANA)National Institute for Materials Science1-1 Namiki, Tsukuba, Ibaraki 305-0044 JapanPhone: +81-29-860-4710E-mail: mana-pr[AT]ml.nims.go.jphttps://samurai.nims.go.jp/profiles/hu_xiao?locale=enhttps://journals.aps.org/prl/abstract/10.1103/PhysRevLett.114.223901