The moiré superlattice of misaligned atomic bilayers paves the way for designing a new class of materials with wide tunability.In this work,we propose a photonic analog of the moiré superlattice based on die...The moiré superlattice of misaligned atomic bilayers paves the way for designing a new class of materials with wide tunability.In this work,we propose a photonic analog of the moiré superlattice based on dielectric resonator quasi-atoms.In sharp contrast to van der Waals materials with weak interlayer coupling,we realize the strong coupling regime in a moiré superlattice,characterized by cascades of robust flat bands at large twist-angles.Surprisingly,we find that these flat bands are characterized by a non-trivial band topology,the origin of which is the moiré pattern of the resonator arrangement.The physical manifestation of the flat band topology is a robust one-dimensional conducting channel on edge,protected by the reflection symmetry of the moiré superlattice.By explicitly breaking the underlying reflection symmetry on the boundary terminations,we show that the first-order topological edge modes naturally deform into higher-order topological corner modes.Our work pioneers the physics of topological phases in the designable platform of photonic moiré superlattices beyond the weakly coupled regime.展开更多
Open quantum and wave systems can exhibit non-Hermitian degeneracies called exceptional points, where both the eigenvalues and the corresponding eigenstates coalesce. Previously, such exceptional points have been inve...Open quantum and wave systems can exhibit non-Hermitian degeneracies called exceptional points, where both the eigenvalues and the corresponding eigenstates coalesce. Previously, such exceptional points have been investigated in dielectric microcavities in terms of optical modes which are well confined inside the cavity. However,beside these so-called "internal modes" with a relatively high quality factor, there exists another kind of mode called "external modes," which have a large decay rate and almost zero intensity inside the cavity. In the present paper, we demonstrate the physical significance of the external modes via the occurrence of exceptional points of internal–external mode pairs for transverse electric polarization. Our numerical studies show that these exceptional points can be achieved by either a boundary deformation of the microdisk or by introducing absorption into a circular cavity.展开更多
A large number of different types of second-order non-Hermitian degeneracies called exceptional points(EPs)were found in various physical systems depending on the mechanism of coupling between eigenstates.We show that...A large number of different types of second-order non-Hermitian degeneracies called exceptional points(EPs)were found in various physical systems depending on the mechanism of coupling between eigenstates.We show that these EPs can be hybridized to form higher-order EPs,which preserve the original properties of the initial EPs before hybridization.For a demonstration,we hybridize chiral and supermode second-order EPs,where the former and the latter are the results of intra-disk and inter-disk mode coupling in an optical system comprised of two Mie-scale microdisks and one Rayleigh-scale scatterer.The high sensitivity of the resulting third-order EP against external perturbations in our feasible system is emphasized.展开更多
Universality class of wave chaos emerges in many areas of science,such as molecular dynamics,optics,and network theory.In this work,we generalize the wave chaos theory to cavity lattice systems by discovering the intr...Universality class of wave chaos emerges in many areas of science,such as molecular dynamics,optics,and network theory.In this work,we generalize the wave chaos theory to cavity lattice systems by discovering the intrinsic coupling of the crystal momentum to the internal cavity dynamics.The cavity-momentum locking substitutes the role of the deformed boundary shape in the ordinary single microcavity problem,providing a new platform for the in situ study of microcavity light dynamics.The transmutation of wave chaos in periodic lattices leads to a phase space reconfiguration that induces a dynamical localization transition.The degenerate scar-mode spinors hybridize and non-trivially localize around regular islands in phase space.In addition,we find that the momentum coupling becomes maximal at the Brillouin zone boundary,so the intercavity chaotic modes coupling and wave confinement are significantly altered.Our work pioneers the study of intertwining wave chaos in periodic systems and provide useful applications in light dynamics control.展开更多
基金We acknowledge financial support from the Institute for Basic Science(IBS)in the Republic of Korea through the project IBS-RO24-D1This work is also supported by Korea Institute for Advanced Study(KIAS).
文摘The moiré superlattice of misaligned atomic bilayers paves the way for designing a new class of materials with wide tunability.In this work,we propose a photonic analog of the moiré superlattice based on dielectric resonator quasi-atoms.In sharp contrast to van der Waals materials with weak interlayer coupling,we realize the strong coupling regime in a moiré superlattice,characterized by cascades of robust flat bands at large twist-angles.Surprisingly,we find that these flat bands are characterized by a non-trivial band topology,the origin of which is the moiré pattern of the resonator arrangement.The physical manifestation of the flat band topology is a robust one-dimensional conducting channel on edge,protected by the reflection symmetry of the moiré superlattice.By explicitly breaking the underlying reflection symmetry on the boundary terminations,we show that the first-order topological edge modes naturally deform into higher-order topological corner modes.Our work pioneers the physics of topological phases in the designable platform of photonic moiré superlattices beyond the weakly coupled regime.
文摘Open quantum and wave systems can exhibit non-Hermitian degeneracies called exceptional points, where both the eigenvalues and the corresponding eigenstates coalesce. Previously, such exceptional points have been investigated in dielectric microcavities in terms of optical modes which are well confined inside the cavity. However,beside these so-called "internal modes" with a relatively high quality factor, there exists another kind of mode called "external modes," which have a large decay rate and almost zero intensity inside the cavity. In the present paper, we demonstrate the physical significance of the external modes via the occurrence of exceptional points of internal–external mode pairs for transverse electric polarization. Our numerical studies show that these exceptional points can be achieved by either a boundary deformation of the microdisk or by introducing absorption into a circular cavity.
基金supported by Ministry of Health and Welfare, Republic of Korea (Government-wide R&D Fund project for infectious disease research, HG18C0069)
文摘A large number of different types of second-order non-Hermitian degeneracies called exceptional points(EPs)were found in various physical systems depending on the mechanism of coupling between eigenstates.We show that these EPs can be hybridized to form higher-order EPs,which preserve the original properties of the initial EPs before hybridization.For a demonstration,we hybridize chiral and supermode second-order EPs,where the former and the latter are the results of intra-disk and inter-disk mode coupling in an optical system comprised of two Mie-scale microdisks and one Rayleigh-scale scatterer.The high sensitivity of the resulting third-order EP against external perturbations in our feasible system is emphasized.
基金We acknowledge financial support from the Institute for Basic Science(IBS)in the Republic of Korea through the project IBS-R024-D1This work is also supported by the research fund of Hanyang University(HY-202300000001149)。
文摘Universality class of wave chaos emerges in many areas of science,such as molecular dynamics,optics,and network theory.In this work,we generalize the wave chaos theory to cavity lattice systems by discovering the intrinsic coupling of the crystal momentum to the internal cavity dynamics.The cavity-momentum locking substitutes the role of the deformed boundary shape in the ordinary single microcavity problem,providing a new platform for the in situ study of microcavity light dynamics.The transmutation of wave chaos in periodic lattices leads to a phase space reconfiguration that induces a dynamical localization transition.The degenerate scar-mode spinors hybridize and non-trivially localize around regular islands in phase space.In addition,we find that the momentum coupling becomes maximal at the Brillouin zone boundary,so the intercavity chaotic modes coupling and wave confinement are significantly altered.Our work pioneers the study of intertwining wave chaos in periodic systems and provide useful applications in light dynamics control.
