Measures of space-time nonseparability of electromagnetic pulses

Shen, Yijie; Zdagkas, Apostolos; Papasimakis, Nikitas; Zheludev, Nikolay I.

doi:10.1103/physrevresearch.3.013236

Cited by 39 publications

(42 citation statements)

References 77 publications

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“…B. Zeldovich in 1957 [366], they are now being carefully examined in optics -both as an electromagnetic response of artificial photonic media endowed with particular topological structural features [367,368], and as a specific toroidal field excitation propagating in free space [369,370]. The latter, known as a toroidal pulse (and sometimes -less descriptively -as a flying doughnut) is particularly interesting in our context here because such wave packets are not separable with respect to their spatial and temporal DoFs [371]. Indeed, the unique properties of toroidal pulses stem from the association between the spatial and temporal DoFs of the pulsed field.…”

Section: Toroidal Pulsesmentioning

confidence: 99%

Space-time wave packets

Yessenov¹,

Hall²,

Schepler³

et al. 2022

Preprint

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Space-time' (ST) wave packets constitute a broad class of pulsed optical fields that are rigidly transported in linear media without diffraction or dispersion, and are therefore propagation-invariant in absence of optical nonlinearities or waveguiding structures. Such wave packets exhibit unique characteristics, such as controllable group velocities in free space and exotic refractive phenomena. At the root of of these behaviors is a fundamental feature underpinning ST wave packets: their spectra are not separable with respect to the spatial and temporal degrees of freedom. Indeed, the spatio-temporal structure is endowed with non-differentiable angular dispersion, in which each spatial frequency is associated with a single prescribed wavelength. Furthermore, deviation from this particular spatio-temporal structure yields novel behaviors that depart from propagation invariance in a precise manner, such as acceleration with an arbitrary axial distribution of the group velocity, tunable dispersion profiles, and Talbot effects in space-time. Although the basic concept of ST wave packets has been known since the 1980's, only very recently has rapid experimental development emerged. These advances are made possible by innovations in spatio-temporal Fourier synthesis, thereby opening a new frontier for structured light at the intersection of beam optics and ultrafast optics. Furthermore, a plethora of novel spatio-temporally structured optical fields (such as flying-focus wave packets, toroidal pulses, and ST optical vortices) are now providing a swathe of surprising characteristics, ranging from tunable group velocities to transverse orbital angular momentum. We review the historical development of ST wave packets, describe the new experimental approach for their efficient synthesis, and enumerate the various new results and potential applications for ST wave packets and other spatio-temporally structured fields that are rapidly accumulating, before casting an eye on a future roadmap for this field.

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Section: Toroidal Pulsesmentioning

confidence: 99%

Space-time wave packets

Yessenov¹,

Hall²,

Schepler³

et al. 2022

Preprint

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“…For instance, the "Flying Doughnut" pulses, or toroidal light pulses (TLPs) first described in 1996 by Hellwarth and Nouchi 29 , with unique spatiotemporal topology predicted recently 30 , have only very recently observed experimentally 31 . Fueled by a combination of advances in ultrafast lasers and metamaterials in our ability to control the spatiotemporal structure of light 32,33 together with the introduction of experimental and theoretical pulse characterization methods [34][35][36][37] , TLPs are attracting growing attention. Indeed, TLPs exhibit their complex topological structure with vector singularities and interact with matter through coupling to toroidal and anapole localized modes [38][39][40][41] .…”

mentioning

confidence: 99%

“…Fuelled by a combination of advances in ultrafast lasers or THz emitters and in our ability to control the spatiotemporal structure of light [29,30] together with the introduction of new experimental and theoretical pulse characterization methods [31,32], TLPs are attracting growing attention. Indeed, TLPs exhibit their complex topological structure with vector singularities and interact with matter through coupling to toroidal and anapole localized modes [33][34][35].…”

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confidence: 99%

Supertoroidal light pulses as electromagnetic skyrmions propagating in free space

et al. 2021

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Topological complex transient electromagnetic fields give access to nontrivial light-matter interactions and provide additional degrees of freedom for information transfer. An important example of such electromagnetic excitations are space-time non-separable single-cycle pulses of toroidal topology, the exact solutions of Maxwell’s equations described by Hellwarth and Nouchi in 1996 and recently observed experimentally. Here we introduce an extended family of electromagnetic excitation, the supertoroidal electromagnetic pulses, in which the Hellwarth-Nouchi pulse is just the simplest member. The supertoroidal pulses exhibit skyrmionic structure of the electromagnetic fields, multiple singularities in the Poynting vector maps and fractal-like distributions of energy backflow. They are of interest for transient light-matter interactions, ultrafast optics, spectroscopy, and toroidal electrodynamics.

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“…134 Furthermore, the inherent mathematical non-separability of spatiotemporally structured light makes it a natural candidate for the next forefront of entanglement studies. 135 The rapid advances made in nanostructured materials offer synergy with the high-order degrees of freedom provided by the spatially and spatiotemporally structured light. As important characteristics of optical fields, photonic AMs play a significant role in light-matter interactions.…”

Section: Optical Information Transmission and Processingmentioning

confidence: 99%