Polarization singularities,which emerge from the incoherent superposition of two vector electric fields with the same frequency,and their evolution in free space are studied analytically and illustrated by numerical e...Polarization singularities,which emerge from the incoherent superposition of two vector electric fields with the same frequency,and their evolution in free space are studied analytically and illustrated by numerical examples.It is shown that there exist C-points,L-lines,in particular,C-lines in incoherently superimposed two-dimensional wavefields.Usually,the C-lines are unstable and disappear during the free-space propagation.The motion,pair creation-annihilation process of the emergent C-points,as well as the distortion of the L-lines may take place,and the degree of polarization of the emergent C-points varies upon propagation and may be less than 1.展开更多
In photonic crystal slab(PCS)structures,the bound states in the continuum(BICs)and circularly polarised states(dubbed C-points)are critical topological polarisation singularities in momentum space that have garnered s...In photonic crystal slab(PCS)structures,the bound states in the continuum(BICs)and circularly polarised states(dubbed C-points)are critical topological polarisation singularities in momentum space that have garnered significant attention owing to their novel topological and optical properties.In this study,we engineered a novel PCS imager featuring two C-points with opposite chirality through symmetry breaking,resulting in maximal asymmetric transmission responses characterised by near-unity circular dichroism(CD)values.By harnessing the chiral selectivity of the C-points,a high-CD PCS imager can provide two sets of optical transfer functions(OTFs)to facilitate both edge detection and bright-field imaging.Notably,one set of OTFs was finely tuned to a Lorentzian line shape to achieve perfect edge detection.We developed a multifunctional imaging system by integrating a PCS imager into a traditional optical system.Both theoretical and experimental demonstrations confirmed that this system provides bright-field and edge-enhanced images with micrometer-scale resolution.Furthermore,these two independent functions can be easily switched by altering the circular polarisation state of the light source.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 10874125)
文摘Polarization singularities,which emerge from the incoherent superposition of two vector electric fields with the same frequency,and their evolution in free space are studied analytically and illustrated by numerical examples.It is shown that there exist C-points,L-lines,in particular,C-lines in incoherently superimposed two-dimensional wavefields.Usually,the C-lines are unstable and disappear during the free-space propagation.The motion,pair creation-annihilation process of the emergent C-points,as well as the distortion of the L-lines may take place,and the degree of polarization of the emergent C-points varies upon propagation and may be less than 1.
基金supported in part by the National Key Research and Development Program of China under Grant 2022YFA1405000in part by the Natural Science Foundation of Jiangsu Province through Major Project under Grant BK20243067+3 种基金in part by the Leading-Edge Technology Program of Jiangsu Natural Science Foundation under Grant BK20232001in part by the National Natural Science Fund for Excellent Young Scholars(Overseas)in part by Fundamental Research Funds for the Central Universitiesin part by Nanjing University Integrated Research Platform of the Ministry of Education-Top Talents Program.
文摘In photonic crystal slab(PCS)structures,the bound states in the continuum(BICs)and circularly polarised states(dubbed C-points)are critical topological polarisation singularities in momentum space that have garnered significant attention owing to their novel topological and optical properties.In this study,we engineered a novel PCS imager featuring two C-points with opposite chirality through symmetry breaking,resulting in maximal asymmetric transmission responses characterised by near-unity circular dichroism(CD)values.By harnessing the chiral selectivity of the C-points,a high-CD PCS imager can provide two sets of optical transfer functions(OTFs)to facilitate both edge detection and bright-field imaging.Notably,one set of OTFs was finely tuned to a Lorentzian line shape to achieve perfect edge detection.We developed a multifunctional imaging system by integrating a PCS imager into a traditional optical system.Both theoretical and experimental demonstrations confirmed that this system provides bright-field and edge-enhanced images with micrometer-scale resolution.Furthermore,these two independent functions can be easily switched by altering the circular polarisation state of the light source.
