Chiral metasurfaces have been proven to possess great potential in chiroptical applications.However,the multiband chiral metasurface with near-perfect circular dichroism has not been well studied.Also,the widely used ...Chiral metasurfaces have been proven to possess great potential in chiroptical applications.However,the multiband chiral metasurface with near-perfect circular dichroism has not been well studied.Also,the widely used bilayer metasurface usually suffers from the interlayer alignment and weak resonance.Here,we propose a twisted Moirémetasurface which can support three chiral bands with near-unity circular dichroism.The Moirémetasurface can remove the restriction of interlayer alignment,while maintaining a strong monolayer resonance.The two chiral bands in the forward direction can be described by two coupled-oscillator models.The third chiral band is achieved by tuning the interlayer chiral mode on resonance with the intralayer mode,to eliminate the parallel and converted components simultaneously.Finally,we study the robustness and tunability of the triple-layer Moirémetasurface in momentum space.This work provides a universal method to achieve three near-unity circular dichroism bands in one metasurface,which can promote applications of chiral metasurfaces in multiband optical communication,chiral drug separation,sensing,optical encryption,chiral laser,nonlinear and quantum optics,etc.展开更多
Metallic nanostructures supporting surface plasmons are crucial for various ultrathin photonic devices.However,these applications are often limited by inherent metallic losses.Significant efforts have been made to ach...Metallic nanostructures supporting surface plasmons are crucial for various ultrathin photonic devices.However,these applications are often limited by inherent metallic losses.Significant efforts have been made to achieve high quality-factor(Q-factor)resonances in plasmonic metasurfaces,particularly through surface lattice resonances(SLRs)and bound states in the continuum(BICs).Despite these advances,a direct comparison between these two mechanisms remains unexplored.Here,we report a reusable plasmonic metasurface that supports multiple high-Q resonances by leveraging hybrid plasmonic–photonic modes.By systematically tuning the lattice constant and dielectric cladding thickness,we achieve substantial Q-factor enhancements of both SLRs and BICs in a monolithic device with a small footprint of 200μm×200μm by using an incoherent light source.A direct comparison between these two resonances is also discussed.This high-Q performance holds significant promise for applications in sensing,lasing,and nonlinear and quantum optics,paving the way for the development of next-generation nanophotonic devices.展开更多
The exceptional point(EP),a degenerate point within non-Hermitian parametric space,has attracted considerable attention,especially for its chiral responses.However,achieving ideal circular dichroism(CD)remains challen...The exceptional point(EP),a degenerate point within non-Hermitian parametric space,has attracted considerable attention,especially for its chiral responses.However,achieving ideal circular dichroism(CD)remains challenging due to the existence of parallel components at the EP.Here,we delve into the theoretical condition required to attain a zero-transmission parallel component.This condition,together with the chiral EP condition,leads to a point characterized by near-unity CD,termed the super chiral EP(SCEP).To illustrate our theoretical framework,we introduce a parity-time symmetric metasurface with gain and loss.The observation of SCEP is demonstrated by tuning both the coupling strength and gain–loss ratio.Furthermore,we explore distinctive properties of SCEP,including phase flip and unidirectional invisibility.Leveraging SCEP and the topological phase transition point,we achieve polarization states across the entire Poincarésurface.This work opens avenues for potential applications in polarizing optical elements,holography,logic gates,chiral molecular detection,ultrasensitive sensing,and polarization-sensitive imaging.展开更多
基金the National Natural Science Foundation of China(Grant Nos.12174031,91950108,and 11774035)。
文摘Chiral metasurfaces have been proven to possess great potential in chiroptical applications.However,the multiband chiral metasurface with near-perfect circular dichroism has not been well studied.Also,the widely used bilayer metasurface usually suffers from the interlayer alignment and weak resonance.Here,we propose a twisted Moirémetasurface which can support three chiral bands with near-unity circular dichroism.The Moirémetasurface can remove the restriction of interlayer alignment,while maintaining a strong monolayer resonance.The two chiral bands in the forward direction can be described by two coupled-oscillator models.The third chiral band is achieved by tuning the interlayer chiral mode on resonance with the intralayer mode,to eliminate the parallel and converted components simultaneously.Finally,we study the robustness and tunability of the triple-layer Moirémetasurface in momentum space.This work provides a universal method to achieve three near-unity circular dichroism bands in one metasurface,which can promote applications of chiral metasurfaces in multiband optical communication,chiral drug separation,sensing,optical encryption,chiral laser,nonlinear and quantum optics,etc.
基金National Natural Science Foundation of China(12174031,91950108,12161141010)National Key R&D Program of China(2022YFA1404301)。
文摘Metallic nanostructures supporting surface plasmons are crucial for various ultrathin photonic devices.However,these applications are often limited by inherent metallic losses.Significant efforts have been made to achieve high quality-factor(Q-factor)resonances in plasmonic metasurfaces,particularly through surface lattice resonances(SLRs)and bound states in the continuum(BICs).Despite these advances,a direct comparison between these two mechanisms remains unexplored.Here,we report a reusable plasmonic metasurface that supports multiple high-Q resonances by leveraging hybrid plasmonic–photonic modes.By systematically tuning the lattice constant and dielectric cladding thickness,we achieve substantial Q-factor enhancements of both SLRs and BICs in a monolithic device with a small footprint of 200μm×200μm by using an incoherent light source.A direct comparison between these two resonances is also discussed.This high-Q performance holds significant promise for applications in sensing,lasing,and nonlinear and quantum optics,paving the way for the development of next-generation nanophotonic devices.
基金National Natural Science Foundation of China(12174031,91950108).
文摘The exceptional point(EP),a degenerate point within non-Hermitian parametric space,has attracted considerable attention,especially for its chiral responses.However,achieving ideal circular dichroism(CD)remains challenging due to the existence of parallel components at the EP.Here,we delve into the theoretical condition required to attain a zero-transmission parallel component.This condition,together with the chiral EP condition,leads to a point characterized by near-unity CD,termed the super chiral EP(SCEP).To illustrate our theoretical framework,we introduce a parity-time symmetric metasurface with gain and loss.The observation of SCEP is demonstrated by tuning both the coupling strength and gain–loss ratio.Furthermore,we explore distinctive properties of SCEP,including phase flip and unidirectional invisibility.Leveraging SCEP and the topological phase transition point,we achieve polarization states across the entire Poincarésurface.This work opens avenues for potential applications in polarizing optical elements,holography,logic gates,chiral molecular detection,ultrasensitive sensing,and polarization-sensitive imaging.
