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Light containing twisted phase structures, i.e. light carrying orbital angular momenta (OAM), when propagating inside ring-core fibers leads to a complex interference dynamics resulting in the fundamental self-imaging phenomenon known as the Talbot effect in the angular domain. We study the effect in the classical and quantum optics domain and show that it can be used to implement higher-order beams splitters. Interestingly, such beam splitting operations become more compact the higher the splitting ratio. In addition, we show that a similar self-imaging effect appears for whispering gallery modes carrying OAM in step-index multi-mode fibers, which enables the application of the angular Talbot effect in off-the-shelf components. Finally, we extend the study of the angular Talbot effect through combing it with its Fourier-analog, i.e. the Talbot effect in orbital angular momentum space. Thereby we implement the generalized angle-orbital-angular-momentum Talbot effect, which enables full control over the angular intensity distribution as well as the OAM spectrum of the light field. Moreover, the complex self-imaging dynamics can be used to sort OAM light fields, in principle, without any crosstalk and, thus, can be seen a promising method for OAM multiplexing schemes.
Advancements in structured ultrafast laser sources have significantly contributed to our understanding of the fundamental dynamics of electronic and spin processes in matter. Notably, the development of ultrafast sources structured in their spin and orbital angular momentum has been pivotal in probing chiral systems and magnetic materials at fundamental temporal and spatial scales. Thanks to the highly nonlinear process of high harmonic generation, structured ultrafast laser pulses have been brought into the extreme ultraviolet/attosecond regimes.
This talk will review significant works from the last decade that have advanced the field of attosecond structured pulses. The discussion will focus on how these pulses can be generated—for example, how to create attosecond vortex pulses—, and how they can provide new insights into our understanding of ultrafast electronic dynamics.
Closing the debate on the transverse orbital angular momentum of spatiotemporal optical vortices
Miguel Ángel Porras
Technical University of Madrid, Spain
We present a theory of the transverse orbital angular momentum (OAM) of spatiotemporal wave packets that explains the different values of the transverse OAM of spatiotemporal optical vortices (STOVs) provided by several authors as belonging to different canonical STOVs. The theory also rules out inaccurate values contributed by other authors, closing the debate on this issue.
1Instituto Nacional de Astrofísica, Óptica y Electrónica, Mexico; 2Academic Division of Information Science and Technology, Juarez Autonomous University of Tabasco, Mexico
A novel class of structured propagating waves with parabolic rotational symmetry is introduced for the first time. These are described by exact solutions of the Helmholtz nonparaxial wave equation. Being the result of the separability of the Helmholtz equation, the intensity of these wavefields remains invariant while propagating along parabolic trajectories exhibiting apparent acceleration. Whe will show that superposition of the different wavefields created can present parabolic, spherical or even rectilinear propagation.
