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Metamaterials based on novel symmetries II

14:00 Invited talk : Exotic spectral singularities in parity-time symmetric cavities

Xiang Zhang, Hamidreza Ramezani

University of California (USA)

We show that the presence of parity-time symmetry, a hallmark of structures with a delicate balance of gain and loss mechanisms, leads to novel lasing schemes with exotic and controllable features. Specifically, in a microring laser, existence of rotational parity-time symmetry leads to intrinsic single-mode lasing regardless of the gain spectral bandwidth. Moreover, an interplay between the Fano resonances and parity-time symmetry in coupled ring cavities with balanced amplification and absorption results in lasing modes with unidirectional emission.
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14:20 Invited talk : Experimental demonstration of Mie-resonance-based transition metamaterials

Natalia Litchinitser (1),Jingbo Sun (1),Zhaxylyk Kudyshev (1),Xiaoming Liu (2),Ji Zhou (2)

(1)The State University of New York (USA) , (2)Tsinghua University (China)

Inhomogeneous metamaterials with materials parameters gradually changing from positive to negative values - so-called transition metamaterials - are of significant interest from both fundamental science and applications viewpoints. This interest is motivated by anomalous field behavior in the vicinity of the transition point, where refractive index, dielectric permittivity and/or magnetic permeability is equal to zero. We report the first experimental demonstration of the predicted field enhancement effect in all-dielectric metamaterials made of high-refractive index dielectric blocks.
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14:40 Invited talk : Loss-induced topological transition of dispersion from a closed elliptic curve to an open hyperbolic curve

Kun Yu, Haitao Jiang, Hong Chen

Tongji University (China)

Topological transitions of dispersion from a closed elliptic curve to an open hyperbolic curve have been realized in dispersive metamaterials by changing the frequency. In this work, we use intrinsic loss in low-permeability medium to induce the topological transition of dispersion at a fixed frequency. By gradually increasing the loss, we study the evolution process of the topological transition.
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15:00 Invited talk : Experimental realization of Bloch oscillations in a Parity-Time synthetic silicon photonic lattice

Xiaoping Liu (1),Yelong Xu (1),William Fegadolli (2),Lin Gan (3),Minghui Lu (1),Liang Feng (4),Axel Scherer (2),Zhiyuan Li (3),Yanfeng Chen (1)

(1)Nanjing University (China) , (2)California Institute of Technology (USA) , (3)Chinese Academy of Sciences (China) , (4)The State University of New York at Buffalo (USA)

As a phenomenon originally discovered for electrons subjected into a periodic potential, Bloch oscillations (BO) have been studied in many other Hermitian physical systems for quantum particles exhibiting wave nature. Here by exploiting the emerging concept of parity-time synthetic photonic system, we experimentally realize for the first time Bloch oscillation in a non-Hermitian silicon photonic lattice consisting of periodic dissipative elements and show that such system gives rise to abundant physics.
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15:20 Invited talk : Spin-Orbit Coupling in Polariton Graphene: Optical Spin Hall Effect and Z Topological Insulator

Dmitry Solnyshkov, Anton Nalitov, Hugo Terças, Guillaume Malpuech

University Blaise Pascal (France)

We show that the TE-TM splitting of planar cavities leads to a special type of spin-orbit coupling for polariton graphene, a honeycomb superstructure formed by pillar microcavities, transforming into an emergent field with Dresselhaus symmetry at the Dirac points of the Brillouin zone. This transformation can be evidenced by the Optical Spin Hall effect. Under an applied magnetic field, polariton graphene behaves as a Z topological insulator with chiral surface states, which can be evidenced by direct resonant excitation.
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15:40 Invited talk : On-Chip Optical Isolator and Circulator Using Active Microcavities without Magneto-Optical (Faraday) Effect

Xiaoshun Jiang (1),Jianming Wen (2),Liang Jiang (2),Min Xiao (3)

(1)Nanjing University (China) , (2)Yale University (USA) , (3)Nanjing University (USA)

Traditional approach on realizing optical isolators and circulators rely mainly on the magneto-optical effect to break time-reversal symmetry. Yet, this approach has difficulty with conventional complementary metal-oxide-semiconductor (CMOS) technology. By exploring gain-saturation induced nonlinearity in active high-Q microtoroid resonators, we here report two of our recent experiments towards the realizations of on-chip optical isolation and circulation. Not only compatible with the existing CMOS technique, our devices also show unprecedented performances even for signal power down to few nanowatts.
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16:00 : Fabrication and ferromagnetic resonance of cobalt chiral meta-molecule arrays

Toshiyuki Kodama, Satoshi Tomita, Nobuyoshi Hosoito, Hisao Yanagi

Nara Institute of Science and Technology (Japan)

We fabricated arrays of micrometer-sized, three-dimensional chiral meta-molecule (CMM) of cobalt (Co) by using a strain-driven self-coiling technique. In the arrays, the Co CMMs were fixed on a silicon substrate and aligned in the same direction. We investigated the ferromagnetic resonance of the arrays with varying angles of external dc magnetic field. The Co CMM arrays show a resonance signal at a much lower field than the Kittel mode.
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