Measurement of the superluminal group velocity of an ultrashort Bessel beam pulse

Phys Rev Lett. 2002 Feb 18;88(7):073901. doi: 10.1103/PhysRevLett.88.073901. Epub 2002 Jan 31.

Abstract

The superluminal group velocity of an ultrashort optical Bessel beam pulse is measured over its entire depth of field, corresponding to approximately 2x10(4) optical wavelengths. The method used is to measure the traveling ionization front induced by the pulse.