We propose a uniform backfire-to-endfire leaky-wave antenna(LWA)based on a topological one-way waveguide under external bias magnetic field.We systematically analyze the dispersion,showing that the proposed structure ...We propose a uniform backfire-to-endfire leaky-wave antenna(LWA)based on a topological one-way waveguide under external bias magnetic field.We systematically analyze the dispersion,showing that the proposed structure supports leaky mode arisen from total internal reflection.By means of tuning frequency or magnetic field,we obtain fixed-bias frequency and fixed-frequency bias LWA with continuous beam scanning from backward,broadside to forward direction.More importantly,we,for the first time,demonstrate that this proposed LWA shows mechanical tunability,allowing us to manipulate the radiation direction from backward,broadside to forward direction by mechanically tuning the air layer thickness.The simulated results show that our system exhibits super low 3dB beam width,high radiation efficiency as well as high antenna gain.Being provided such multiple controlled(especially mechanically)beam scanning manners,the present LWA paves an advanced approach for continuous beam scanning,holding a great potential for applications in modern communication and radar system.展开更多
Dynamic topological photonics is a novel research field, combining the time-domain optics and topological physics.In this review, the recent progress and realization platforms of dynamic topological photonics have bee...Dynamic topological photonics is a novel research field, combining the time-domain optics and topological physics.In this review, the recent progress and realization platforms of dynamic topological photonics have been well introduced.The definition, measurement methods and the evolution process of the dynamic topological photonics are demonstrated to better understand the physical diagram. This review is meant to bring the readers a different perspective on topological photonics, grasp the advanced progress of dynamic topology, and inspire ideas about future prospects.展开更多
Topological photonic states(TPSs)as a new type of waveguide state with one-way transport property can resist backscattering and are impervious to defects,disorders and metallic obstacles.Gyromagnetic photonic crystal(...Topological photonic states(TPSs)as a new type of waveguide state with one-way transport property can resist backscattering and are impervious to defects,disorders and metallic obstacles.Gyromagnetic photonic crystal(GPC)is the first artificial microstructure to implement TPSs,and it is also one of the most important platforms for generating truly one-way TPSs and exploring their novel physical properties,transport phenomena,and advanced applications.Herein,we present a brief review of the fundamental physics,novel properties,and practical applications of TPSs based on GPCs.We first examine chiral one-way edge states existing in uniformly magnetized GPCs of ordered and disordered lattices,antichiral one-way edge states in cross magnetized GPCs,and robust one-way bulk states in heterogeneously magnetized GPCs.Then,we discuss the strongly coupling effect between two co-propagating(or counter-propagating)TPSs and the resulting physical phenomena and device applications.Finally,we analyze the key issues and prospect the future development trends for TPSs in GPCs.The purpose of this brief review is to provide an overview of the main features of TPSs in GPC systems and offer a useful guidance and motivation for interested scientists and engineers working in related scientific and technological areas.展开更多
In this paper, we demonstrated a compact Si-SiO2 waveguide coupler with a footprint of only 2 μm × 3 μm by topology optimization in the communication wavelength. The transmission was increased from 30% to 100%,...In this paper, we demonstrated a compact Si-SiO2 waveguide coupler with a footprint of only 2 μm × 3 μm by topology optimization in the communication wavelength. The transmission was increased from 30% to 100%, much higher than other methods. Besides, the optimized structure did not incorporate other dielectric materials, facilitating fabrications and applications.展开更多
Antichiral gyromagnetic photonic crystal(GPC)in a honeycomb lattice with the two interpenetrating triangular sublattices A and B magnetically biased in opposite directions can realize antichiral one-way edge states pr...Antichiral gyromagnetic photonic crystal(GPC)in a honeycomb lattice with the two interpenetrating triangular sublattices A and B magnetically biased in opposite directions can realize antichiral one-way edge states propagating along the same direction at its two parallel edges.Here,we report the construction and observation of topological beam splitting with the easily adjustable right-to-left ratio in an antichiral GPC.The splitter is compact and configurable,has high trans-mission efficiency,and allows for multi-channel utilization,crosstalk-proof,and robust against defects and obstacles.This magnificent performance is attributed to the peculiar property that antichiral one-way edge states exist only at zigzag edge but not at armchair edge of antichiral GPC.When we combine two rectangular antichiral GPCs holding left-and right-propagating antichiral one-way edge states respectively,bidirectionally radiating one-way edge states at two paral-lel zigzag edges can be achieved.Our observations can enrich the understanding of fundamental physics and expand to-pological photonic applications.展开更多
Square-root topological insulators recently discovered are intriguing topological phases.They possess topological properties inherited from the squared Hamiltonian and exhibit double-band structures.The mechanism of t...Square-root topological insulators recently discovered are intriguing topological phases.They possess topological properties inherited from the squared Hamiltonian and exhibit double-band structures.The mechanism of the square root was generalized to 2^(n)-root topological insulators,giving rise to more band gaps.In this study,we describe the experimental realization of onedimensional 2^(n)-root topological insulators in photonic waveguide arrays using the archetypical Su-Schrieffer-Heeger(SSH)model.Topological edge states with tunable numbers are clearly observed under visible light.In particular,we visualized the dynamic evolutions of the light propagation by varying the sample lengths,which further proved the localization and multiple numbers of edge states in 2^(n)-root topological systems.The experiment,which involves constructing 2^(n)-root topological photonic lattices in various geometric arrangements,provides a stable platform for studying topological states that exhibit a remarkable degree of flexibility and control.展开更多
Floquet topological insulators(FTIs) have been used to study the topological features of a dynamic quantum system within the band structure. However, it is difficult to directly observe the dynamic modulation of band ...Floquet topological insulators(FTIs) have been used to study the topological features of a dynamic quantum system within the band structure. However, it is difficult to directly observe the dynamic modulation of band structures in FTIs. Here, we implement the dynamic Su–Schrieffer–Heeger model in periodically curved waveguides to explore new behaviors in FTIs using light field evolutions. Changing the driving frequency produces near-field evolutions of light in the high-frequency curved waveguide array that are equivalent to the behaviors in straight arrays. Furthermore, at modest driving frequencies,the field evolutions in the system show boundary propagation, which are related to topological edge modes. Finally, we believe curved waveguides enable profound possibilities for the further development of Floquet engineering in periodically driven systems, which ranges from condensed matter physics to photonics.展开更多
One-dimensional(1D)one-way waveguides based on topological edge states of two-dimensional(2D)gyromagnetic photonic crystals have been studied extensively.Here,we theoretically propose a three-dimensional(3D)all-dielec...One-dimensional(1D)one-way waveguides based on topological edge states of two-dimensional(2D)gyromagnetic photonic crystals have been studied extensively.Here,we theoretically propose a three-dimensional(3D)all-dielectric gyromagnetic photonic crystal with type-Ⅱ Weyl points.Based on the inclined band properties of the type-Ⅱ Weyl surface states,we design a 2D one-way interface transmission channel on the Weyl crystal.Light waves in such 2D waveguides can be transmitted robustly over metal obstacles almost without any back-reflection,topologically protected by the type-Ⅱ Weyl points.By manipulating the magnetic field or structural parameters,we also achieve the topological phase transition between Weyl phase and 3D Chern insulator phase and obtain the corresponding phase diagram,which provides more possibilities for topological regulation of the surface states.This work suggests a new way to construct unidirectional 2D waveguides with larger area of energy transmission in 3D space,which is a promising platform for developing 3D topological photonic devices.展开更多
基金This work was supported by the National Natural Science Foundation of China(NSFC)(Grant No.61372005)the National Natural Science Foundation of China(NSFC)under the key project(Grant No.41331070)+1 种基金the Natural Science Foundation of Ningbo(No.2019A610081)Zhejiang Provincial Natural Science Foundation of China(No.LY20F050006).
文摘We propose a uniform backfire-to-endfire leaky-wave antenna(LWA)based on a topological one-way waveguide under external bias magnetic field.We systematically analyze the dispersion,showing that the proposed structure supports leaky mode arisen from total internal reflection.By means of tuning frequency or magnetic field,we obtain fixed-bias frequency and fixed-frequency bias LWA with continuous beam scanning from backward,broadside to forward direction.More importantly,we,for the first time,demonstrate that this proposed LWA shows mechanical tunability,allowing us to manipulate the radiation direction from backward,broadside to forward direction by mechanically tuning the air layer thickness.The simulated results show that our system exhibits super low 3dB beam width,high radiation efficiency as well as high antenna gain.Being provided such multiple controlled(especially mechanically)beam scanning manners,the present LWA paves an advanced approach for continuous beam scanning,holding a great potential for applications in modern communication and radar system.
基金Project supported by the National Key Research and Development Program of China (Grant No.2018YFB2200403)the National Natural Science Foundation of China (Grant Nos.91950204 and 92150302)。
文摘Dynamic topological photonics is a novel research field, combining the time-domain optics and topological physics.In this review, the recent progress and realization platforms of dynamic topological photonics have been well introduced.The definition, measurement methods and the evolution process of the dynamic topological photonics are demonstrated to better understand the physical diagram. This review is meant to bring the readers a different perspective on topological photonics, grasp the advanced progress of dynamic topology, and inspire ideas about future prospects.
基金Project supported by Guangdong Provincial Innovative and Entrepreneurial Research Team Program(Grant No.2016ZT06C594)the Science and Technology Project of Guangdong Province,China(Grant No.2020B010190001)the National Key Research and Development Programof China(Grant No.2018YFA 0306200).
文摘Topological photonic states(TPSs)as a new type of waveguide state with one-way transport property can resist backscattering and are impervious to defects,disorders and metallic obstacles.Gyromagnetic photonic crystal(GPC)is the first artificial microstructure to implement TPSs,and it is also one of the most important platforms for generating truly one-way TPSs and exploring their novel physical properties,transport phenomena,and advanced applications.Herein,we present a brief review of the fundamental physics,novel properties,and practical applications of TPSs based on GPCs.We first examine chiral one-way edge states existing in uniformly magnetized GPCs of ordered and disordered lattices,antichiral one-way edge states in cross magnetized GPCs,and robust one-way bulk states in heterogeneously magnetized GPCs.Then,we discuss the strongly coupling effect between two co-propagating(or counter-propagating)TPSs and the resulting physical phenomena and device applications.Finally,we analyze the key issues and prospect the future development trends for TPSs in GPCs.The purpose of this brief review is to provide an overview of the main features of TPSs in GPC systems and offer a useful guidance and motivation for interested scientists and engineers working in related scientific and technological areas.
文摘In this paper, we demonstrated a compact Si-SiO2 waveguide coupler with a footprint of only 2 μm × 3 μm by topology optimization in the communication wavelength. The transmission was increased from 30% to 100%, much higher than other methods. Besides, the optimized structure did not incorporate other dielectric materials, facilitating fabrications and applications.
基金the National Natural Science Foundation of China(11974119)Science and Technology Project of Guangdong(2020B010190001)+1 种基金Guangdong Innovative and Entrepreneurial Research Team Program(2016ZT06C594)National Key R&D Program of China(2018YFA 0306200).
文摘Antichiral gyromagnetic photonic crystal(GPC)in a honeycomb lattice with the two interpenetrating triangular sublattices A and B magnetically biased in opposite directions can realize antichiral one-way edge states propagating along the same direction at its two parallel edges.Here,we report the construction and observation of topological beam splitting with the easily adjustable right-to-left ratio in an antichiral GPC.The splitter is compact and configurable,has high trans-mission efficiency,and allows for multi-channel utilization,crosstalk-proof,and robust against defects and obstacles.This magnificent performance is attributed to the peculiar property that antichiral one-way edge states exist only at zigzag edge but not at armchair edge of antichiral GPC.When we combine two rectangular antichiral GPCs holding left-and right-propagating antichiral one-way edge states respectively,bidirectionally radiating one-way edge states at two paral-lel zigzag edges can be achieved.Our observations can enrich the understanding of fundamental physics and expand to-pological photonic applications.
基金This work was supported by the Key R&D Program of Guangzhou(Grant No.202007020003)Guangzhou Basic and Applied Basic Research(Grant Nos.202201010407,202201010428)+1 种基金the Basic and Applied Basic Research Foundation of Guangdong Province(Grant Nos.2021A1515110475,2022A1515011289,2023A1515012666)the National Natural Science Foundation of China(Grant Nos.62122027,52002128,62075063,51772101,51872095,12204179,52202004).
文摘Square-root topological insulators recently discovered are intriguing topological phases.They possess topological properties inherited from the squared Hamiltonian and exhibit double-band structures.The mechanism of the square root was generalized to 2^(n)-root topological insulators,giving rise to more band gaps.In this study,we describe the experimental realization of onedimensional 2^(n)-root topological insulators in photonic waveguide arrays using the archetypical Su-Schrieffer-Heeger(SSH)model.Topological edge states with tunable numbers are clearly observed under visible light.In particular,we visualized the dynamic evolutions of the light propagation by varying the sample lengths,which further proved the localization and multiple numbers of edge states in 2^(n)-root topological systems.The experiment,which involves constructing 2^(n)-root topological photonic lattices in various geometric arrangements,provides a stable platform for studying topological states that exhibit a remarkable degree of flexibility and control.
基金supported by the National Natural Science Foundation of China (Nos. 11874266 and 11604208)the Shanghai Science and Technology Committee (Nos. 16ZR1445600 and 16ZR1445500)the ChenGuang Program (No. 17CG49)。
文摘Floquet topological insulators(FTIs) have been used to study the topological features of a dynamic quantum system within the band structure. However, it is difficult to directly observe the dynamic modulation of band structures in FTIs. Here, we implement the dynamic Su–Schrieffer–Heeger model in periodically curved waveguides to explore new behaviors in FTIs using light field evolutions. Changing the driving frequency produces near-field evolutions of light in the high-frequency curved waveguide array that are equivalent to the behaviors in straight arrays. Furthermore, at modest driving frequencies,the field evolutions in the system show boundary propagation, which are related to topological edge modes. Finally, we believe curved waveguides enable profound possibilities for the further development of Floquet engineering in periodically driven systems, which ranges from condensed matter physics to photonics.
基金supported by the National Natural Science Foundation of China(Grant No.11974119)Science and Technology Project of Guangdong(Grant No.2020B010190001)+1 种基金Guangdong Innovative and Entrepreneurial Research Team Program(Grant No.2016ZT06C594)National Key R&D Program of China(Grant No.2018YFA0306200)。
文摘One-dimensional(1D)one-way waveguides based on topological edge states of two-dimensional(2D)gyromagnetic photonic crystals have been studied extensively.Here,we theoretically propose a three-dimensional(3D)all-dielectric gyromagnetic photonic crystal with type-Ⅱ Weyl points.Based on the inclined band properties of the type-Ⅱ Weyl surface states,we design a 2D one-way interface transmission channel on the Weyl crystal.Light waves in such 2D waveguides can be transmitted robustly over metal obstacles almost without any back-reflection,topologically protected by the type-Ⅱ Weyl points.By manipulating the magnetic field or structural parameters,we also achieve the topological phase transition between Weyl phase and 3D Chern insulator phase and obtain the corresponding phase diagram,which provides more possibilities for topological regulation of the surface states.This work suggests a new way to construct unidirectional 2D waveguides with larger area of energy transmission in 3D space,which is a promising platform for developing 3D topological photonic devices.
