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Metamaterials based on novel symmetries IV

14:00 Invited talk : Dielectric metasurfaces for phase, amplitude and polarization control

Uriel Levy, Boris Desiatov, Jonathan Bar David

The Hebrew University of Jerusalem (Israel)

In this talk we present our recent work on dielectric metasurfaces for phase, amplitude and polarization control. We show new results in the near IR and the mid IR regime, in which the control over the properties of light can be achieve by controlling the retardation of a subwavelength periodic structure or by controlling the resonances of nano beams in semiconductors. We discuss approaches for achieving broadband retardation of light by tailoring the dispersion properties of the metasurface.
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14:20 : Photonic Analogue of Quantum Spin Hall Effect

Xiao-Chen Sun, Cheng He, Xiaoping Liu, Ming-Hui Lu, Yan-Feng Chen

Nanjing University (China)

Recently, some works doubt that the robustness of the previous reported photonic topological insulators (PTIs) is not protected by time-reversal (TR) symmetry, which destroys the foundation of the principle of topological insulator (TI). To clarify the symmetry protected mechanism of PTIs, we introduce a new symmetry operator, which has the similar form with TR symmetry operator of electrons. By constructing photonic crystal, we demonstrate that the there will always be TI phenomenon protected by such new symmetry.
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14:35 : PT - symmetry, complex coordinates, and the suppression of reflection

Simon Horsley

University of Exeter (United Kingdom)

In this talk I will explain when it can be useful to treat space - time coordinates as complex numbers. Our results demonstrate that there is a simple way to control reflection from an inhomogeneous medium in terms of the properties of the permittivity in the complex position plane, and that this is intimately related to PT - symmetry.
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14:50 : Manipulating gauge-field with metamaterials

Fu Liu (1),Simon Horsley (2),Jensen Li (1)

(1)University of Birmingham (United Kingdom) , (2)University of Exeter (United Kingdom)

By considering the local symmetries of a special duality operation in exchanging electric and magnetic fields for two dimensional wave propagation, we identify a real-space gauge field realized using reciprocal anisotropic metamaterials. It manipulates waves by shifting the centers of local dispersion surfaces instead of varying their sizes and shapes. It allows us to design spin-enabled optical devices, such as beam splitters, waveguides with asymmetric transmission and invisibility cloaks.
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15:05 : Transition between propagation, perfect absorption and lasing states in energy-balanced materials with both gain and loss

Ping Bai (1),Ying Wu (2),Yun Lai (1)

(1)Soochow University (China) , (2)King Abdullah University of Science and Technology (Saudi Arabia)

We investigate the propagation of electromagnetic waves in materials with both gain and loss in either permittivity or permeability. When the gain and loss are balanced with refractive index being a real number, such materials can support propagating waves like media without gain or loss. Based on photonic crystals with both gain and loss, we have achieved effective media of such energy-balanced materials.
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15:20 : Roles of PT and RT symmetries in non-reciprocal periodic photonic systems: simple examples

Kin Hung Fung

The Hong Kong Polytechnic University (Hong Kong)

We discuss the roles of PT symmetry and RT symmetry in phenomena associated with non-reciprocal dispersion. We present a one-way surface mode in a PT symmetric magnetized photonic system at effective mu close to zero. The new mode is non-propagating when the system is infinite while it becomes propagating in the finite case. In another example, we show that a magnetized diatomic chain of plasmonic nanoparticles can support non-reciprocal dispersion and its relation to RT symmetry.
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