Propagation and wavefront ambiguity of linear nondiffracting beams

摘要: Ultrashort-pulsed Bessel and Airy beams in free space are often interpreted as "linear light bullets". Usually, interconnected intensity profiles considered a "propagation" along arbitrary pathways which can even follow curved trajectories. A more detailed analysis, however, shows that this picture gives an adequate description only situations do not require to consider the transport of optical signals or causality. To also cover these special cases, generalization terms "beam" is necessary. The problem becomes clearer by representing angular spectra propagating wave fields rays Poynting vectors. It known quasi-nondiffracting be described caustics ray bundles. Their decomposition into vectors Shack-Hartmann sensors indicates that, frame their classical definition, corresponding local wavefronts ambiguous concepts based on energy density appropriate describe propagation completely. For reason, quantitative parameters like beam factor have treated with caution well. applications communication computing, alternative descriptions required. heuristic approach vector field information Fourier analysis proposed here. Continuity discontinuity far distributions time discussed. Quantum aspects briefly addressed.