Energy backflow in unidirectional spatiotemporally localized wavepackets

Abstract

Backflow, or retro-propagation, is a counterintuitive phenomenon where for a forward-propagating wave the energy or probability density locally propagates backward. In this study the energy backflow has been examined in connection with relatively simple causal unidirectional finite-energy solutions of the wave equation which are derived from a factorization of the so-called basic splash mode. Specific results are given for the energy backflow arising in known azimuthally symmetric unidirectional wavepackets, as well as in novel azimuthally asymmetric extensions. Using the Bateman-Whittaker technique, a novel finite-energy unidirectional null localized wave has been constructed that is devoid of energy backflow and has some of the topological properties of the basic Hopfion.

10 pages, 8 figures. In comparison with v1, some refs. to arXiv have been updated by journal ones, some paragraphs in Introduction revised and a remark about possible experimental verification added to Conclusions

References in corpus (7)

• Diffraction-free space-time beams
• Abruptly Focusing and Defocusing Needles of Light and Closed-Form Electromagnetic Wavepackets
• Unidirectional decomposition method for obtaining exact localized waves solutions totally free of backward components
• Demonstrating backflow in classical two beams' interference
• Backflow in relativistic wave equations
• Backward energy flow in simple 4-wave electromagnetic fields
• Comment on "Backflow in relativistic wave equations"

Cited by in corpus (2)

• Study of energy backflow in unidirectional monochromatic and space-time waves
• Wave pulses with unusual asymptotical behavior at infinity