We predict the existence of a specific wave object that arises when a spatially limited electromagnetic wave with an abrupt leading edge propagates in a vacuum. This object demonstrates a precursorlike behavior, since the diffraction spreading of the field proceeds behind it. The transverse structure and the field strength at the leading edge of the object remain unchanged during propagation, whereas the object’s energy decreases as z−1 (z is the distance of propagation) because of diffractive erosion of its trailing edge. We show that this phenomenon resembles to a certain extent the Sommerfeld precursor formation in a temporally dispersive medium.
© 1994 Optical Society of America
Original Manuscript: May 6, 1992
Revised Manuscript: May 26, 1993
Manuscript Accepted: May 26, 1993
Published: January 1, 1994
E. M. Belenov and A. V. Nazarkin, "Transient diffraction and precursorlike effects in vacuum," J. Opt. Soc. Am. A 11, 168-172 (1994)