Links and knots are exotic topological structures that have garnered significant interest across multiple branches of natural sciences.Coherent links and knots,such as those constructed by phase or polarization singul...Links and knots are exotic topological structures that have garnered significant interest across multiple branches of natural sciences.Coherent links and knots,such as those constructed by phase or polarization singularities of coherent light,have been observed in various three-dimensional optical settings.However,incoherent links and knots—knotted or connected lines of coherence singularities—arise from a fundamentally different concept.They are"hidden"in the statistic properties of a randomly fluctuating field,making their presence often elusive or undetectable.Here,we theoretically construct and experimentally demonstrate such topological entities of incoherent light.By leveraging a state-of-the-art incoherent modal-decomposition scheme,we unveil incoherent topological structures from fluctuating light speckles,including Hopf links and Trefoil knots of coherence singularities that are robust against coherence and intensity fluctuations.Our work is applicable to diverse wave systems where incoherence or practical coherence is prevalent,and may pave the way for design and implementation of statistically-shaped topological structures for various applications such as high-dimensional optical information encoding and optical communications.展开更多
<div style="text-align:justify;"> The analytical expression of the cross-spectral density of partially coherent elegant Laguerre-Gaussian beams propagating in free space has been derived. The coherence...<div style="text-align:justify;"> The analytical expression of the cross-spectral density of partially coherent elegant Laguerre-Gaussian beams propagating in free space has been derived. The coherence vortex properties of such beams have been investigated. The effect of the beam parameters, including the topological charge, radial mode index and coherence length on the coherent vortex, is analyzed. The results show that the higher order (lth) of coherent vortices split to lth first order of coherent vortex. New coherent vortices of opposite sign appear, and then pairs of coherent vortices form. The propagation distance and coherence length affect the generation of coherent vortices, while the radial mode index doesn’t affect the coherent vortices. These results might be helpful for potential application of such beams in optical communication. </div>展开更多
It has been over 30 years since the concept of optical vortices was first proposed by Coullet et al.in 1989,and the field of structured beams has grown extremely.In the last two decades,partially coherent vortex beams...It has been over 30 years since the concept of optical vortices was first proposed by Coullet et al.in 1989,and the field of structured beams has grown extremely.In the last two decades,partially coherent vortex beams(PCVBs)have received increasing interest in the fields of optical manipulation,optical communication,optical imaging,etc.,and great progress has been made in the area of the coherence singularities,generation methods,topological charge measurements,and promising applications of PCVBs.In this review,we firstly outline the basic concepts of PCVBs.We explicate the relationship between the coherence vortices and optical vortices,and the evolution behavior of optical vortices to coherence vortices is summarized in detail.We discuss a special form of coherence singularity,ring dislocation,mathematically and physically.The ring dislocation in the correlation functions under low coherence is dependent on the mode indices,which provide a feasible approach to measure mode indices of PCVBs.Subsequently,we summarize the various methods for measuring the topological charge of PCVBs,highlight the measurement method based on the cross-correlation function,and a physical explanation on the relation between ring dislocation and topological charge is given.After that,we review the recent advances on experimental generation of several kinds of PCVBs.Lastly,we give an overview on the potential applications of PCVBs.展开更多
基金supported by the National Key Research and Development Program of China(No.2022YFA1404800)National Natural Science Foundation of China(No.12174280,No.12204340,No.12192254,No.92250304,No.12434012,No.W2441005)Priority Academic Program Development of Jiangsu Higher Education Institutions,and Postgraduate Research&Practice Innovation Programof Jiangsu Province(KYCX24_3287).
文摘Links and knots are exotic topological structures that have garnered significant interest across multiple branches of natural sciences.Coherent links and knots,such as those constructed by phase or polarization singularities of coherent light,have been observed in various three-dimensional optical settings.However,incoherent links and knots—knotted or connected lines of coherence singularities—arise from a fundamentally different concept.They are"hidden"in the statistic properties of a randomly fluctuating field,making their presence often elusive or undetectable.Here,we theoretically construct and experimentally demonstrate such topological entities of incoherent light.By leveraging a state-of-the-art incoherent modal-decomposition scheme,we unveil incoherent topological structures from fluctuating light speckles,including Hopf links and Trefoil knots of coherence singularities that are robust against coherence and intensity fluctuations.Our work is applicable to diverse wave systems where incoherence or practical coherence is prevalent,and may pave the way for design and implementation of statistically-shaped topological structures for various applications such as high-dimensional optical information encoding and optical communications.
文摘<div style="text-align:justify;"> The analytical expression of the cross-spectral density of partially coherent elegant Laguerre-Gaussian beams propagating in free space has been derived. The coherence vortex properties of such beams have been investigated. The effect of the beam parameters, including the topological charge, radial mode index and coherence length on the coherent vortex, is analyzed. The results show that the higher order (lth) of coherent vortices split to lth first order of coherent vortex. New coherent vortices of opposite sign appear, and then pairs of coherent vortices form. The propagation distance and coherence length affect the generation of coherent vortices, while the radial mode index doesn’t affect the coherent vortices. These results might be helpful for potential application of such beams in optical communication. </div>
基金supported by the National Natural Science Foundation of China(Grant Nos.11874102,11525418,91750201,and 11974218)the Sichuan Province Science and Technology Support Program(Grant No.20CXRC0086)+1 种基金the Innovation Group of Jinan(Grant No.2018GXRC010)the Fundamental Research Funds for the Central Universities(Grant No.ZYGX2019J102)。
文摘It has been over 30 years since the concept of optical vortices was first proposed by Coullet et al.in 1989,and the field of structured beams has grown extremely.In the last two decades,partially coherent vortex beams(PCVBs)have received increasing interest in the fields of optical manipulation,optical communication,optical imaging,etc.,and great progress has been made in the area of the coherence singularities,generation methods,topological charge measurements,and promising applications of PCVBs.In this review,we firstly outline the basic concepts of PCVBs.We explicate the relationship between the coherence vortices and optical vortices,and the evolution behavior of optical vortices to coherence vortices is summarized in detail.We discuss a special form of coherence singularity,ring dislocation,mathematically and physically.The ring dislocation in the correlation functions under low coherence is dependent on the mode indices,which provide a feasible approach to measure mode indices of PCVBs.Subsequently,we summarize the various methods for measuring the topological charge of PCVBs,highlight the measurement method based on the cross-correlation function,and a physical explanation on the relation between ring dislocation and topological charge is given.After that,we review the recent advances on experimental generation of several kinds of PCVBs.Lastly,we give an overview on the potential applications of PCVBs.
