The current understanding of topological insulators and their classical wave analogs,such as photonic topological insulators,is mainly based on topological band theory.However,standard band theory does not apply to am...The current understanding of topological insulators and their classical wave analogs,such as photonic topological insulators,is mainly based on topological band theory.However,standard band theory does not apply to amorphous phases of matter,which are formed by non-crystalline lattices with no long-range positional order but only shortrange order,exhibiting unique phenomena such as the glass-to-liquid transition.Here,we experimentally investigate amorphous variants of a Chern number-based photonic topological insulator.By tuning the disorder strength in the lattice,we demonstrate that photonic topological edge states can persist into the amorphous regime prior to the glass-to-liquid transition.After the transition to a liquid-like lattice configuration,the signatures of topological edge states disappear.This interplay between topology and short-range order in amorphous lattices paves the way for new classes of non-crystalline topological photonic bandgap materials.展开更多
We construct an electrical circuit to realize a modified Haldane lattice exhibiting the phenomenon of antichiral edge states. The circuit consists of a network of inductors and capacitors with interconnections reprodu...We construct an electrical circuit to realize a modified Haldane lattice exhibiting the phenomenon of antichiral edge states. The circuit consists of a network of inductors and capacitors with interconnections reproducing the effects of a magnetic vector potential. The next nearest neighbor hoppings are configured differently from the standard Haldane model, and as predicted by earlier theoretical studies, this gives rise to antichiral edge states that propagate in the same direction on opposite edges and coexist with bulk states at the same frequency. Using pickup coils to measure voltage distributions in the circuit, we experimentally verify the key features of the antichiral edge states, including their group velocities and ability to propagate consistently in a M?bius strip configuration.展开更多
We demonstrate terahertz(THz) frequency laser emission around 3.2 THz from localized modes in one-dimensional disordered grating systems. The disordered structures are patterned on top of the double-metal waveguide of...We demonstrate terahertz(THz) frequency laser emission around 3.2 THz from localized modes in one-dimensional disordered grating systems. The disordered structures are patterned on top of the double-metal waveguide of a THz quantum cascade laser. Multiple emission peaks are observed within a frequency range corresponding to the bandgap of a periodic counterpart with no disorder, indicating the presence of mode localization aided by Bragg scattering. Simulations and experimental measurements provide strong evidence for the spatial localization of the THz laser modes.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2016YFB1200100)the program of the China Scholarships Council(No.201806075001)sponsored by Singapore MOE Academic Research Fund Tier 3 Grant MOE2016-T3-1-006,Tier 1 Grants RG187/18 and RG174/16(S),and Tier 2 Grant MOE 2018-T2-1-022(S).
文摘The current understanding of topological insulators and their classical wave analogs,such as photonic topological insulators,is mainly based on topological band theory.However,standard band theory does not apply to amorphous phases of matter,which are formed by non-crystalline lattices with no long-range positional order but only shortrange order,exhibiting unique phenomena such as the glass-to-liquid transition.Here,we experimentally investigate amorphous variants of a Chern number-based photonic topological insulator.By tuning the disorder strength in the lattice,we demonstrate that photonic topological edge states can persist into the amorphous regime prior to the glass-to-liquid transition.After the transition to a liquid-like lattice configuration,the signatures of topological edge states disappear.This interplay between topology and short-range order in amorphous lattices paves the way for new classes of non-crystalline topological photonic bandgap materials.
基金supported by the National Natural Science Foundation of China(Grant Nos.11874274,and 12004425)the Natural Science Foundation of Jiangsu Province(Grant Nos.BK20170058,and BK20200630)+1 种基金a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)supported by the Singapore MOE Academic Research Fund Tier 3(Grant No.MOE2016-T3-1006)。
文摘We construct an electrical circuit to realize a modified Haldane lattice exhibiting the phenomenon of antichiral edge states. The circuit consists of a network of inductors and capacitors with interconnections reproducing the effects of a magnetic vector potential. The next nearest neighbor hoppings are configured differently from the standard Haldane model, and as predicted by earlier theoretical studies, this gives rise to antichiral edge states that propagate in the same direction on opposite edges and coexist with bulk states at the same frequency. Using pickup coils to measure voltage distributions in the circuit, we experimentally verify the key features of the antichiral edge states, including their group velocities and ability to propagate consistently in a M?bius strip configuration.
基金Ministry of Education-Singapore(MOE)(MOE 2016-T2-1-128)Agency for Science,Technology and Research(A*STAR)(1426500050)+2 种基金National Research Foundation Singapore(NRF)(NRF-CRP18-2017-02)Engineering and Physical Sciences Research Council(EPSRC)(EP/P021859/1)Royal Society and Wolfson Foundation
文摘We demonstrate terahertz(THz) frequency laser emission around 3.2 THz from localized modes in one-dimensional disordered grating systems. The disordered structures are patterned on top of the double-metal waveguide of a THz quantum cascade laser. Multiple emission peaks are observed within a frequency range corresponding to the bandgap of a periodic counterpart with no disorder, indicating the presence of mode localization aided by Bragg scattering. Simulations and experimental measurements provide strong evidence for the spatial localization of the THz laser modes.
