%0 Journal Article
%A Porras, Miguel A.
%A Gonzalo Fonrodona, Isabel
%A Mondello, Alessia
%T Pulsed light beams in vacuum with superluminal and negative group velocities
%D 2003
%@ 1539-3755
%U https://hdl.handle.net/20.500.14352/51361
%X We study the group velocity of pulsed light beams in vacuum. Gouy's phase associated with the diffraction of transversally limited pulses can create a strong anomalous dispersion in vacuum leading to highly superluminal and negative group velocities. As a consequence, a focusing pulse can diverge beyond the focus before converging into it. The experimental feasibility is discussed.
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