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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Toroidal and reverse flux of light in the sharp focus
摘要： We obtain a set of explicit analytical expressions that completely describe a light field with a double higher-order singularity (phase and polarization), as well as distributions of its intensity and energy flux near the focus.There is a reverse energy flux on the optical axis near the focus, which is comparable in magnitude with the forward flux. There is a toroidal energy flux in the focal area near the dark rings in the distribution of the longitudinal component of the Poynting vector.
关键词： cylindrical vector beam,optical vortex,energy backflow,toroidal vortex,tight focusing
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - A Topologically Robust Formation of Broadband Vortices Propagating at the Speed of Light
摘要： We show that Flying Doughnuts, the exact propagating solutions of Maxwell equations in the form of single-cycle toroidal pulses have complex and robust fine topological structure of spectrally broadband vortices and extended areas of energy backflow. The study of the topology of electromagnetic waves provides insights into their fine-scale structure and can reveal information about their propagation dynamics. Typically, such studies are focused on vortices and polarization singularities of monochromatic light beams [1,2]. Here, we present a study of the singularities in the electromagnetic fields and Poynting vector of a single-cycle toroidal pulse, termed Flying Doughnut (FD). FD pulses are exact solutions of Maxwell's equations with known analytical form. Thus, such exotic forms of light are inherently stable under propagation and can be scrutinised at extraordinary level of detail. FDs propagate in free-space at the speed of light and their interactions with matter include non-trivial field transformations upon reflection from metallic and dielectric interfaces. The field configuration of the FDs is topologically similar to the toroidal dipolar excitations in matter, which allows to excite strong toroidal response and engage anapole modes (non-radiating configurations of electric and toroidal dipoles) in dielectric particles. It has been suggested that the longitudinal field components could be employed for the acceleration of charged particles.
关键词： toroidal pulses,anapole modes,broadband vortices,Maxwell equations,energy backflow,Poynting vector,Flying Doughnuts
更新于2025-09-16 10:30:52