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Physical Optics|107 Article(s)
Symmetric and asymmetric Hall effect-like splitting of optical Stokes skyrmions via a hybrid multi-zone filter
Tian Xia, Jia Ma, Zhenwei Xie, and Xiaocong Yuan
In recent years, optical skyrmions have garnered increasing attention for their ability to introduce new degrees of freedom in manipulating optical fields. While most research has focused on creating innovative optical topological states such as merons and hopfions, there has been limited exploration into their manipulation, which hinders practical applications in this field. In this study, we utilize a hybrid multi-zone filter to induce a Hall effect-like splitting of optical Stokes skyrmions (HESSs), enabling effective separation and manipulation. By manipulating the horizontal phase gradient parameter, we independently control the separation angle of skyrmions. Additionally, we demonstrate control over the topological charge parameter to achieve symmetric and asymmetric HESSs. This effect not only enhances the manipulation capabilities of optical fields but also opens up potential applications for high precision displacement measurements and preservation quantum information. In recent years, optical skyrmions have garnered increasing attention for their ability to introduce new degrees of freedom in manipulating optical fields. While most research has focused on creating innovative optical topological states such as merons and hopfions, there has been limited exploration into their manipulation, which hinders practical applications in this field. In this study, we utilize a hybrid multi-zone filter to induce a Hall effect-like splitting of optical Stokes skyrmions (HESSs), enabling effective separation and manipulation. By manipulating the horizontal phase gradient parameter, we independently control the separation angle of skyrmions. Additionally, we demonstrate control over the topological charge parameter to achieve symmetric and asymmetric HESSs. This effect not only enhances the manipulation capabilities of optical fields but also opens up potential applications for high precision displacement measurements and preservation quantum information.
Photonics Research
- Publication Date: Apr. 30, 2025
- Vol. 13, Issue 5, 1365 (2025)
Spin angular momentum engineering within highly localized focal fields: from simple orientation to complex topologies|Editors' Pick
Yongxi Zeng, Yanzhong Yu, Jian Chen, Houan Teng, Musheng Chen, Pinghui Wu, and Qiwen Zhan
Optical skyrmions, as quasiparticles with non-trivial topological structures, have garnered significant attention in recent years. This paper proposes a method for customized spin angular momentum (SAM) distribution in highly localized focal fields, thereby enabling the generation of SAM skyrmion and bimeron topologies. The skyrmionic SAM textures can be flexibly controlled, such as polarity, vorticity, and helicity. In addition, the two-dimensional projection plane can be arbitrarily oriented within three-dimensional space. By utilizing time-reversal techniques, we obtain the required illumination fields of the 4π-focusing system and subsequently evaluate the tightly focused field using vector Debye integral theory. Our results show that the SAM orientation within the focal field is controlled by the orientation of orthogonal dipole pairs. Using the radiation field of a multi-concentric array of orthogonal dipole pairs, the distribution of SAM orientation in the target plane can be tailored to generate SAM topological structures such as skyrmions and bimerons. Highly localized and tunable SAM engineering holds great potential for applications in optical manipulation, light–matter interactions, optical information processing, transmission, and storage. Optical skyrmions, as quasiparticles with non-trivial topological structures, have garnered significant attention in recent years. This paper proposes a method for customized spin angular momentum (SAM) distribution in highly localized focal fields, thereby enabling the generation of SAM skyrmion and bimeron topologies. The skyrmionic SAM textures can be flexibly controlled, such as polarity, vorticity, and helicity. In addition, the two-dimensional projection plane can be arbitrarily oriented within three-dimensional space. By utilizing time-reversal techniques, we obtain the required illumination fields of the 4π-focusing system and subsequently evaluate the tightly focused field using vector Debye integral theory. Our results show that the SAM orientation within the focal field is controlled by the orientation of orthogonal dipole pairs. Using the radiation field of a multi-concentric array of orthogonal dipole pairs, the distribution of SAM orientation in the target plane can be tailored to generate SAM topological structures such as skyrmions and bimerons. Highly localized and tunable SAM engineering holds great potential for applications in optical manipulation, light–matter interactions, optical information processing, transmission, and storage.
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 995 (2025)
Floquet engineering with spatially nonuniform driving fields
Stella T. Schindler, and Hanan Herzig Sheinfux
In Floquet engineering, we apply a time-periodic modulation to change the effective behavior of a wave system. In this work, we generalize Floquet engineering to more fully exploit spatial degrees of freedom, expanding the scope of effective behaviors we can access. We develop a perturbative procedure to engineer space-time dependent driving forces that effectively transform broad classes of tight-binding systems into one another. We demonstrate several applications, including removing disorder, undoing Anderson localization, and enhancing localization to an extreme in spatially modulated waveguides. This procedure straightforwardly extends to other types of physical systems and different Floquet driving field implementations. In Floquet engineering, we apply a time-periodic modulation to change the effective behavior of a wave system. In this work, we generalize Floquet engineering to more fully exploit spatial degrees of freedom, expanding the scope of effective behaviors we can access. We develop a perturbative procedure to engineer space-time dependent driving forces that effectively transform broad classes of tight-binding systems into one another. We demonstrate several applications, including removing disorder, undoing Anderson localization, and enhancing localization to an extreme in spatially modulated waveguides. This procedure straightforwardly extends to other types of physical systems and different Floquet driving field implementations.
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 905 (2025)
Sculpting isolated optical vortex knots on demand
Dmitrii Tsvetkov, Danilo G. Pires, Hooman Barati Sedeh, and Natalia M. Litchinitser
The rapid development of optical technologies, including optical trapping, enhanced imaging, and microscopy, necessitates fundamentally new approaches to higher-dimensional optical beam shaping. We introduce a rigorous theoretical approach for sculpting three-dimensional, topological particle-like objects, such as optical knots or links, including precise control of their individual parts. Universally applicable to knots created using braided zero lines, our method is validated through theoretical analysis and experimental measurements. The proposed approach enables new degrees of freedom in multi-dimensional singularities shaping, including rotations, shifts, and rescaling of their parts for enhanced stability in complex media. These results may find applications in the fields of three-dimensional optical trapping, manipulation, and subwavelength microscopy, as well as probing and imaging through atmospheric or underwater turbulence. The rapid development of optical technologies, including optical trapping, enhanced imaging, and microscopy, necessitates fundamentally new approaches to higher-dimensional optical beam shaping. We introduce a rigorous theoretical approach for sculpting three-dimensional, topological particle-like objects, such as optical knots or links, including precise control of their individual parts. Universally applicable to knots created using braided zero lines, our method is validated through theoretical analysis and experimental measurements. The proposed approach enables new degrees of freedom in multi-dimensional singularities shaping, including rotations, shifts, and rescaling of their parts for enhanced stability in complex media. These results may find applications in the fields of three-dimensional optical trapping, manipulation, and subwavelength microscopy, as well as probing and imaging through atmospheric or underwater turbulence.
Photonics Research
- Publication Date: Jan. 31, 2025
- Vol. 13, Issue 2, 527 (2025)
Rotational Doppler effect using ultra-dense vector perfect vortex beams
Jianbo Gao, Xingyuan Lu, Xuechun Zhao, Zhuoyi Wang, Junan Zhu, Zhiquan Hu, Jingjing He, Qiwen Zhan, Yangjian Cai, and Chengliang Zhao
The rotational Doppler effect holds significant potential for remote sensing of rotating objects due to its real-time performance and non-contact advantages. A single-ring beam is used to measure rotation speed. To enhance the signal-to-noise ratio and measure additional parameters, multiple rings are introduced in the context of a rotational Doppler effect. However, the interference between these rings poses a challenge for multitasking detection applications. In this study, cross-polarization superposition was applied to generate an ultra-dense vector perfect vortex beam that exhibited sensitivity to spatial position and object size, and flexibility in designing topological charge combinations for generating frequency combs. A proof-of-principle experiment was conducted to demonstrate its capability in improving the signal-to-noise ratio, and accurately perceiving both the radius of rotation and radial size. An ultra-dense vector perfect vortex beam provides a general strategy for beam construction and the multi-parameter perception of rotating objects, thereby enabling potential applications in the measurement of velocity gradient measurement of fluids. The rotational Doppler effect holds significant potential for remote sensing of rotating objects due to its real-time performance and non-contact advantages. A single-ring beam is used to measure rotation speed. To enhance the signal-to-noise ratio and measure additional parameters, multiple rings are introduced in the context of a rotational Doppler effect. However, the interference between these rings poses a challenge for multitasking detection applications. In this study, cross-polarization superposition was applied to generate an ultra-dense vector perfect vortex beam that exhibited sensitivity to spatial position and object size, and flexibility in designing topological charge combinations for generating frequency combs. A proof-of-principle experiment was conducted to demonstrate its capability in improving the signal-to-noise ratio, and accurately perceiving both the radius of rotation and radial size. An ultra-dense vector perfect vortex beam provides a general strategy for beam construction and the multi-parameter perception of rotating objects, thereby enabling potential applications in the measurement of velocity gradient measurement of fluids.
Photonics Research
- Publication Date: Jan. 30, 2025
- Vol. 13, Issue 2, 468 (2025)
Propagation dynamics of a spatiotemporal vortex pulse in the spatial fractional system
Jinqi Song, Fengqi Liu, Mingli Sun, Xiangyu Tong, Naichen Zhang, Bingsong Cao, Wenzhe Wang, Kaikai Huang, Xian Zhang, and Xuanhui Lu
The dynamics of wave packets carrying a spatiotemporal vortex in the spatial fractional system is still an open problem. The difficulty stems from the fact that the fractional Laplacian derivative is essentially a nonlocal operator, and the vortex is space-time coupled. Here, we investigate the transmission of spatiotemporal vortices in the spatial fractional wave equation (FWE) and demonstrate the effects of linewidth, vortex topological charge, and linear chirp modulation on the transmission of Bessel-type spatiotemporal vortex pulses (BSTVPs). Under narrowband conditions, we find that the propagation of BSTVP in the FWE can be seen as the coherent superposition of two linearly shifted half-BSTVPs and can reveal orbital angular momentum backflow for the half-BSTVP. Our analysis can be extended to other spatiotemporal vortex pulses. The dynamics of wave packets carrying a spatiotemporal vortex in the spatial fractional system is still an open problem. The difficulty stems from the fact that the fractional Laplacian derivative is essentially a nonlocal operator, and the vortex is space-time coupled. Here, we investigate the transmission of spatiotemporal vortices in the spatial fractional wave equation (FWE) and demonstrate the effects of linewidth, vortex topological charge, and linear chirp modulation on the transmission of Bessel-type spatiotemporal vortex pulses (BSTVPs). Under narrowband conditions, we find that the propagation of BSTVP in the FWE can be seen as the coherent superposition of two linearly shifted half-BSTVPs and can reveal orbital angular momentum backflow for the half-BSTVP. Our analysis can be extended to other spatiotemporal vortex pulses.
Photonics Research
- Publication Date: Aug. 30, 2024
- Vol. 12, Issue 9, 2027 (2024)
Optical edge-to-screw singularity state conversions
Haolin Lin, Junhui Jia, Guohua Liu, Yanwen Hu, Zhen Li, Zhenqiang Chen, and Shenhe Fu
Optical singularity states, which significantly affect propagation properties of light in free space or optical medium, can be geometrically classified into screw and edge types. These different types of singularity states do not exhibit direct connection, being decoupled from each other in the absence of external perturbations. Here we demonstrate a novel optical process in which a higher-order edge singularity state initially nested in the propagating Gaussian light field gradually involves into a screw singularity with a new-born topological charge determined by order of the edge state. The considered edge state comprises an equal superposition of oppositely charged vortex and antivortex modes. We theoretically and experimentally realize this edge-to-screw conversion process by introducing intrinsic vortex–antivortex interaction. We also present a geometrical representation for mapping this dynamical process, based on the higher-order orbital Poincaré sphere. Within this framework, the edge-to-screw conversion is explained by a mapping of state evolution from the equator to the north or south pole of the Poincaré sphere. Our demonstration provides a novel approach for manipulating singularity state by the intrinsic vortex–antivortex interactions. The presented phenomenon can be also generalized to other wave systems such as matter wave, water wave, and acoustic wave. Optical singularity states, which significantly affect propagation properties of light in free space or optical medium, can be geometrically classified into screw and edge types. These different types of singularity states do not exhibit direct connection, being decoupled from each other in the absence of external perturbations. Here we demonstrate a novel optical process in which a higher-order edge singularity state initially nested in the propagating Gaussian light field gradually involves into a screw singularity with a new-born topological charge determined by order of the edge state. The considered edge state comprises an equal superposition of oppositely charged vortex and antivortex modes. We theoretically and experimentally realize this edge-to-screw conversion process by introducing intrinsic vortex–antivortex interaction. We also present a geometrical representation for mapping this dynamical process, based on the higher-order orbital Poincaré sphere. Within this framework, the edge-to-screw conversion is explained by a mapping of state evolution from the equator to the north or south pole of the Poincaré sphere. Our demonstration provides a novel approach for manipulating singularity state by the intrinsic vortex–antivortex interactions. The presented phenomenon can be also generalized to other wave systems such as matter wave, water wave, and acoustic wave.
Photonics Research
- Publication Date: Jul. 26, 2024
- Vol. 12, Issue 8, 1689 (2024)
Rotational Doppler effect of composite vortex beams with tailored OAM spectra
Yutian Liang, Ruijian Li, Jie Zhao, Xingyuan Lu, Tong Liu, Zhengliang Liu, Yuan Ren, and Chengliang Zhao
There recently has been increasing interest in the research and application of the rotational Doppler effect (RDE), which paves a promising way to detect rotating objects remotely. In order to obtain more information about the rotating object from the rotational Doppler signal, composite vortex beams by coaxial superposition of orbital angular momentum (OAM) modes are often used as the probe beam. However, to the best of our knowledge, the RDE of composite vortex beams with arbitrary OAM spectra has not yet been comprehensively studied. In this paper, the correspondence between the OAM spectrum of a probe beam and the frequency spectrum of a rotational Doppler signal is theoretically analyzed. It is explicitly revealed that the RDE frequency spectrum of scattered light is related to the product of two autocorrelation functions: one from the OAM spectrum of probe beam and the other from the spiral spectrum of rotating object. On the basis of this relation, one can regulate the RDE frequency spectrum on demand via tailoring the OAM spectrum of the probe beam. As a proof of concept we design a special composite vortex beam to eliminate the broadening of the RDE spectrum induced by misalignment. These findings are of practical value in applications such as remote sensing and optical metrology. There recently has been increasing interest in the research and application of the rotational Doppler effect (RDE), which paves a promising way to detect rotating objects remotely. In order to obtain more information about the rotating object from the rotational Doppler signal, composite vortex beams by coaxial superposition of orbital angular momentum (OAM) modes are often used as the probe beam. However, to the best of our knowledge, the RDE of composite vortex beams with arbitrary OAM spectra has not yet been comprehensively studied. In this paper, the correspondence between the OAM spectrum of a probe beam and the frequency spectrum of a rotational Doppler signal is theoretically analyzed. It is explicitly revealed that the RDE frequency spectrum of scattered light is related to the product of two autocorrelation functions: one from the OAM spectrum of probe beam and the other from the spiral spectrum of rotating object. On the basis of this relation, one can regulate the RDE frequency spectrum on demand via tailoring the OAM spectrum of the probe beam. As a proof of concept we design a special composite vortex beam to eliminate the broadening of the RDE spectrum induced by misalignment. These findings are of practical value in applications such as remote sensing and optical metrology.
Photonics Research
- Publication Date: Jul. 26, 2024
- Vol. 12, Issue 8, 1665 (2024)
Controllable split polarization singularities for ultra-precise displacement sensing
Jiakang Zhou, Haixiang Ma, Shuoshuo Zhang, Wu Yuan, Changjun Min, Xiaocong Yuan, and Yuquan Zhang
The topic of optical precise displacement measurement has garnered significant attention and generated widespread interest recently. The use of optical singularity offers a potential solution for this purpose, although effectively manipulating the singularity in an ideal manner remains challenging. In this work, we propose a theoretical approach to achieve controllable position modulation of the C-point in the focal plane, whose spatial position can be easily modulated by adjusting the relative offset factor β and the offset angle α of an azimuthal polarization beam (APB), while the interval and orientation of the C-points can be flexibly regulated. Notably, the chiral polarization state undergoes a distinct reversal along the link-line connecting the two C-points, thereby providing a promising approach for accurate displacement sensing. To evaluate its sensing characteristics, the varying pattern of the scattered field intensity is monitored when sweeping a gold helix and nanoparticle along the link-line. The results of simulation quality index Q verify that the equilibrium factor of the scattering field possesses an obvious linear relationship with the displacement, signifying a precise sub-nanometric sensitivity. This research introduces new methods for the flexible control of polarization singularities in tightly focused fields, thereby enhancing the utilization of circular polarization properties near C-points for displacement sensing. These findings not only enrich the field of nanometer measurement technology but also pave the way for new avenues of research in this domain. The topic of optical precise displacement measurement has garnered significant attention and generated widespread interest recently. The use of optical singularity offers a potential solution for this purpose, although effectively manipulating the singularity in an ideal manner remains challenging. In this work, we propose a theoretical approach to achieve controllable position modulation of the C-point in the focal plane, whose spatial position can be easily modulated by adjusting the relative offset factor β and the offset angle α of an azimuthal polarization beam (APB), while the interval and orientation of the C-points can be flexibly regulated. Notably, the chiral polarization state undergoes a distinct reversal along the link-line connecting the two C-points, thereby providing a promising approach for accurate displacement sensing. To evaluate its sensing characteristics, the varying pattern of the scattered field intensity is monitored when sweeping a gold helix and nanoparticle along the link-line. The results of simulation quality index Q verify that the equilibrium factor of the scattering field possesses an obvious linear relationship with the displacement, signifying a precise sub-nanometric sensitivity. This research introduces new methods for the flexible control of polarization singularities in tightly focused fields, thereby enhancing the utilization of circular polarization properties near C-points for displacement sensing. These findings not only enrich the field of nanometer measurement technology but also pave the way for new avenues of research in this domain.
Photonics Research
- Publication Date: Jul. 01, 2024
- Vol. 12, Issue 7, 1478 (2024)
Dual-curvilinear beam enabled tunable manipulation of high- and low-refractive-index particles
Zheng Yuan, Chenchen Zhang, Yuan Gao, Wenxiang Yan, Xian Long, Zhi-Cheng Ren, Xi-Lin Wang, Jianping Ding, and Hui-Tian Wang
We present an innovative approach for the simultaneous agile manipulation of high-refractive-index (HRI) and low-refractive-index (LRI) particles. Our method involves introducing a dual-curvilinear optical vortex beam (DC-OVB) generated by superimposing a pair of curved beams: HRI and LRI particles are controlled by the bright curve and the dark channel between the two curves, respectively. The proposed DC-OVB provides customizable motion paths and velocities for both LRI and HRI particles. Each curve of the DC-OVB can support a distinct orbital flow density (OFD), enabling the application of torques to HRI and LRI particles, guiding them to orbit along specified trajectories and prompting them to execute various curvilinear motions simultaneously, including curvilinear movement, revolution, and rotation. We present an innovative approach for the simultaneous agile manipulation of high-refractive-index (HRI) and low-refractive-index (LRI) particles. Our method involves introducing a dual-curvilinear optical vortex beam (DC-OVB) generated by superimposing a pair of curved beams: HRI and LRI particles are controlled by the bright curve and the dark channel between the two curves, respectively. The proposed DC-OVB provides customizable motion paths and velocities for both LRI and HRI particles. Each curve of the DC-OVB can support a distinct orbital flow density (OFD), enabling the application of torques to HRI and LRI particles, guiding them to orbit along specified trajectories and prompting them to execute various curvilinear motions simultaneously, including curvilinear movement, revolution, and rotation.
Photonics Research
- Publication Date: Jun. 14, 2024
- Vol. 12, Issue 7, 1427 (2024)
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