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      Chalcogenide Phase Change Material for Active Terahertz Photonics

      1 , 2 , 1 , 2 , 3 , 4 , 3 , 4 , 3 , 4 , 5 , 6 , 7 , 1 , 2
      Advanced Materials
      Wiley

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          Most cited references43

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          Phase-change materials for rewriteable data storage.

          Phase-change materials are some of the most promising materials for data-storage applications. They are already used in rewriteable optical data storage and offer great potential as an emerging non-volatile electronic memory. This review looks at the unique property combination that characterizes phase-change materials. The crystalline state often shows an octahedral-like atomic arrangement, frequently accompanied by pronounced lattice distortions and huge vacancy concentrations. This can be attributed to the chemical bonding in phase-change alloys, which is promoted by p-orbitals. From this insight, phase-change alloys with desired properties can be designed. This is demonstrated for the optical properties of phase-change alloys, in particular the contrast between the amorphous and crystalline states. The origin of the fast crystallization kinetics is also discussed.
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            Graphene plasmonics for tunable terahertz metamaterials.

            Plasmons describe collective oscillations of electrons. They have a fundamental role in the dynamic responses of electron systems and form the basis of research into optical metamaterials. Plasmons of two-dimensional massless electrons, as present in graphene, show unusual behaviour that enables new tunable plasmonic metamaterials and, potentially, optoelectronic applications in the terahertz frequency range. Here we explore plasmon excitations in engineered graphene micro-ribbon arrays. We demonstrate that graphene plasmon resonances can be tuned over a broad terahertz frequency range by changing micro-ribbon width and in situ electrostatic doping. The ribbon width and carrier doping dependences of graphene plasmon frequency demonstrate power-law behaviour characteristic of two-dimensional massless Dirac electrons. The plasmon resonances have remarkably large oscillator strengths, resulting in prominent room-temperature optical absorption peaks. In comparison, plasmon absorption in a conventional two-dimensional electron gas was observed only at 4.2 K (refs 13, 14). The results represent a first look at light-plasmon coupling in graphene and point to potential graphene-based terahertz metamaterials.
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              Active terahertz metamaterial devices.

              The development of artificially structured electromagnetic materials, termed metamaterials, has led to the realization of phenomena that cannot be obtained with natural materials. This is especially important for the technologically relevant terahertz (1 THz = 10(12) Hz) frequency regime; many materials inherently do not respond to THz radiation, and the tools that are necessary to construct devices operating within this range-sources, lenses, switches, modulators and detectors-largely do not exist. Considerable efforts are underway to fill this 'THz gap' in view of the useful potential applications of THz radiation. Moderate progress has been made in THz generation and detection; THz quantum cascade lasers are a recent example. However, techniques to control and manipulate THz waves are lagging behind. Here we demonstrate an active metamaterial device capable of efficient real-time control and manipulation of THz radiation. The device consists of an array of gold electric resonator elements (the metamaterial) fabricated on a semiconductor substrate. The metamaterial array and substrate together effectively form a Schottky diode, which enables modulation of THz transmission by 50 per cent, an order of magnitude improvement over existing devices.
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                Author and article information

                Contributors
                Journal
                Advanced Materials
                Adv. Mater.
                Wiley
                0935-9648
                1521-4095
                January 27 2019
                March 2019
                January 27 2019
                March 2019
                : 31
                : 12
                : 1808157
                Affiliations
                [1 ]Division of Physics and Applied PhysicsSchool of Physical and Mathematical SciencesNanyang Technological University 21 Nanyang Link Singapore 637371 Singapore
                [2 ]Centre for Disruptive Photonic TechnologiesThe Photonic Institute 50 Nanyang Avenue Singapore 639798 Singapore
                [3 ]NUSNNI‐NanoCoreNational University of Singapore Singapore 117411 Singapore
                [4 ]NUS Graduate School for Integrative Science and EngineeringNational University of Singapore Singapore 117456 Singapore
                [5 ]Department of PhysicsNational University of Singapore Singapore 117542 Singapore
                [6 ]Department of Electrical and Computer EngineeringNational University of Singapore Singapore 117583 Singapore
                [7 ]Department of Materials Science and EngineeringNational University of Singapore Singapore 117575 Singapore
                Article
                10.1002/adma.201808157
                de770f65-1417-41e1-909c-8ea494c5de2f
                © 2019

                http://onlinelibrary.wiley.com/termsAndConditions#vor

                http://doi.wiley.com/10.1002/tdm_license_1.1

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