As one of the most attractive non-radiative power transfer mechanisms without cables,efficient magnetic resonance wireless power transfer(WPT)in the near field has been extensively developed in recent years,and promot...As one of the most attractive non-radiative power transfer mechanisms without cables,efficient magnetic resonance wireless power transfer(WPT)in the near field has been extensively developed in recent years,and promoted a variety of practical applications,such as mobile phones,medical implant devices and electric vehicles.However,the physical mechanism behind some key limitations of the resonance WPT,such as frequency splitting and size-dependent efficiency,is not very clear under the widely used circuit model.Here,we review the recently developed efficient and stable resonance WPT based on non-Hermitian physics,which starts from a completely different avenue(utilizing loss and gain)to introduce novel functionalities to the resonance WPT.From the perspective of non-Hermitian photonics,the coherent and incoherent effects compete and coexist in the WPT system,and the weak stable of energy transfer mainly comes from the broken phase associated with the phase transition of parity-time symmetry.Based on this basic physical framework,some optimization schemes are proposed,including using nonlinear effect,using bound states in the continuum,or resorting to the system with high-order parity-time symmetry.Moreover,the combination of non-Hermitian physics and topological photonics in multi-coil system also provides a versatile platform for long-range robust WPT with topological protection.Therefore,the non-Hermitian physics can not only exactly predict the main results of current WPT systems,but also provide new ways to solve the difficulties of previous designs.展开更多
Topological systems containing near-field or far-field couplings between unit cells have been widely investigated in quantum and classic systems.Their band structures are well explained with theories based on tight-bi...Topological systems containing near-field or far-field couplings between unit cells have been widely investigated in quantum and classic systems.Their band structures are well explained with theories based on tight-binding or multiple scattering formalism.However,characteristics of the topology of the bulk bands based on the joint modulation of near-field and far-field couplings are rarely studied.Such hybrid systems are hardly realized in real systems and cannot be described by neither tight-binding nor multiple scattering theories.Here,we propose a hybrid-coupling photonic topological insulator based on a quasi-1D dimerized chain with the coexistence of near-field coupling within the unit cell and far-field coupling among all sites.Both theoretical and experimental results show that topological transition is realized by introducing near-field coupling for given far-field coupling conditions.In addition to closing and reopening the bandgap,the change in near-field coupling modulates the effective mass of photonics in the upper band from positive to negative,leading to an indirect bandgap,which cannot be achieved in conventional dimerized chains with either far-field or near-field coupling only.展开更多
基金supported by the National Key Research and Development Program of China (Grant No. 2016YFA0301101)the National Natural Science Foundation of China (Grant Nos. 91850206, 61621001, 2004284, 11674247, and 11974261)+3 种基金Shanghai Science and Technology Committee, China (Grant Nos. 18JC1410900 and 18ZR1442900)the China Postdoctoral Science Foundation (Grant Nos. 2019TQ0232 and 2019M661605)the Shanghai Super Postdoctoral Incentive ProgramFundamental Research Funds for the Central Universities, China
文摘As one of the most attractive non-radiative power transfer mechanisms without cables,efficient magnetic resonance wireless power transfer(WPT)in the near field has been extensively developed in recent years,and promoted a variety of practical applications,such as mobile phones,medical implant devices and electric vehicles.However,the physical mechanism behind some key limitations of the resonance WPT,such as frequency splitting and size-dependent efficiency,is not very clear under the widely used circuit model.Here,we review the recently developed efficient and stable resonance WPT based on non-Hermitian physics,which starts from a completely different avenue(utilizing loss and gain)to introduce novel functionalities to the resonance WPT.From the perspective of non-Hermitian photonics,the coherent and incoherent effects compete and coexist in the WPT system,and the weak stable of energy transfer mainly comes from the broken phase associated with the phase transition of parity-time symmetry.Based on this basic physical framework,some optimization schemes are proposed,including using nonlinear effect,using bound states in the continuum,or resorting to the system with high-order parity-time symmetry.Moreover,the combination of non-Hermitian physics and topological photonics in multi-coil system also provides a versatile platform for long-range robust WPT with topological protection.Therefore,the non-Hermitian physics can not only exactly predict the main results of current WPT systems,but also provide new ways to solve the difficulties of previous designs.
基金National Key Research and Development Program of China(2020YFA0211400,2020YFA0211402)National Natural Science Foundation of China(91850206,11974261,61621001,12104105)+1 种基金Shanghai Pujiang Program(21PJ1411400)Fundamental Research Funds for the Central Universities。
文摘Topological systems containing near-field or far-field couplings between unit cells have been widely investigated in quantum and classic systems.Their band structures are well explained with theories based on tight-binding or multiple scattering formalism.However,characteristics of the topology of the bulk bands based on the joint modulation of near-field and far-field couplings are rarely studied.Such hybrid systems are hardly realized in real systems and cannot be described by neither tight-binding nor multiple scattering theories.Here,we propose a hybrid-coupling photonic topological insulator based on a quasi-1D dimerized chain with the coexistence of near-field coupling within the unit cell and far-field coupling among all sites.Both theoretical and experimental results show that topological transition is realized by introducing near-field coupling for given far-field coupling conditions.In addition to closing and reopening the bandgap,the change in near-field coupling modulates the effective mass of photonics in the upper band from positive to negative,leading to an indirect bandgap,which cannot be achieved in conventional dimerized chains with either far-field or near-field coupling only.