Laplace operation,the isotropic second-order differentiation,on spatial functions is an essential mathematical calculation in most physical equations and signal processing.Realizing the Laplace operation in a manner o...Laplace operation,the isotropic second-order differentiation,on spatial functions is an essential mathematical calculation in most physical equations and signal processing.Realizing the Laplace operation in a manner of optical analog computing has recently attracted attention,but a compact device with a high spatial resolution is still elusive.Here,we introduce a Laplace metasurface that can perform the Laplace operation for incident lightfield patterns.By exciting the quasi-bound state in the continuum,an optical transfer function for nearly perfect isotropic second-order differentiation has been obtained with a spatial resolution of wavelength scale.Such a Laplace metasurface has been numerically validated with both 1D and 2D spatial functions,and the results agree well with that of the ideal Laplace operation.In addition,the edge detection of a concerned object in an image has been demonstrated with the Laplace metasurface.Our results pave the way to the applications of metasurfaces in optical analog computing and image processing.展开更多
Non-Hermitian topological systems,by combining the advantages of topological robustness and sensitivity induced by nonHermiticity,have recently emerged and attracted much research interest.Here,we propose a device bas...Non-Hermitian topological systems,by combining the advantages of topological robustness and sensitivity induced by nonHermiticity,have recently emerged and attracted much research interest.Here,we propose a device based on the topological coupler in elastic waves with non-Hermiticity,which contains two topological domain walls and four ports.In this device,topological robustness routes the transmission of waves,while non-Hermiticity controls the gain or loss of waves as they propagate.These mechanisms result in continuous and quantitative control of the energy distribution ratio of each port.A nonHermitian Hamiltonian is introduced to reveal the coupling mechanism of the topological coupler,and a scattering matrix is proposed to predict the energy distribution ratio of each port.The proposed topological coupler,which provides a new paradigm for the non-Hermitian topological systems,can be employed as a sensitive beam splitter or a coupler switch.Moreover,the topological coupler has potential applications in information processing and logic operation in elastic circuits or networks,and the paradigm also applies to other classical systems.展开更多
基金National Key Research and Development Program of China(2019YFB1803904)Guangdong Basic and Applied Basic Research Foundation(2021A1515010257)+3 种基金National Natural Science Foundation of China(61805104,61875076,61935013,U2001601)Fundamental Research Funds for the Central Universities(21619411)Open Project of Wuhan National Laboratory for Optoelectronics(2018WNLOKF015)Leading Talents of Guangdong Province Program(00201502)。
文摘Laplace operation,the isotropic second-order differentiation,on spatial functions is an essential mathematical calculation in most physical equations and signal processing.Realizing the Laplace operation in a manner of optical analog computing has recently attracted attention,but a compact device with a high spatial resolution is still elusive.Here,we introduce a Laplace metasurface that can perform the Laplace operation for incident lightfield patterns.By exciting the quasi-bound state in the continuum,an optical transfer function for nearly perfect isotropic second-order differentiation has been obtained with a spatial resolution of wavelength scale.Such a Laplace metasurface has been numerically validated with both 1D and 2D spatial functions,and the results agree well with that of the ideal Laplace operation.In addition,the edge detection of a concerned object in an image has been demonstrated with the Laplace metasurface.Our results pave the way to the applications of metasurfaces in optical analog computing and image processing.
基金supported by the Research Grants Council of Hong Kong(Grant Nos.16302218,C6013-18G)support by the National Natural Science Foundation of China(Grant Nos.11574216,61505114)。
文摘Non-Hermitian topological systems,by combining the advantages of topological robustness and sensitivity induced by nonHermiticity,have recently emerged and attracted much research interest.Here,we propose a device based on the topological coupler in elastic waves with non-Hermiticity,which contains two topological domain walls and four ports.In this device,topological robustness routes the transmission of waves,while non-Hermiticity controls the gain or loss of waves as they propagate.These mechanisms result in continuous and quantitative control of the energy distribution ratio of each port.A nonHermitian Hamiltonian is introduced to reveal the coupling mechanism of the topological coupler,and a scattering matrix is proposed to predict the energy distribution ratio of each port.The proposed topological coupler,which provides a new paradigm for the non-Hermitian topological systems,can be employed as a sensitive beam splitter or a coupler switch.Moreover,the topological coupler has potential applications in information processing and logic operation in elastic circuits or networks,and the paradigm also applies to other classical systems.
