Abstract

The problem of ultrashort pulse propagation in linear dispersive media has been discussed since the beginning of the century. The fascinating question is: Does the front of a steeply rising pulse traverse a dielectric medium without, any essential delay and distortion, because it takes time to "build up" the refractive index of the material via the polarization by the incident electromagnetic field? Early theoretical approaches of Sommerfeld /1/ and Brillouin /2/ investigated the response of a dielectric to a truncated sinusoidal field. These calculations predict the occurrence of precursors in the transient response corresponding to the high and low frequency components, respectively, of the broad spectrum contained in a steplike pulse with an infinitely fast rising edge. As a result of the dispersive properties of the material these frequency components are considerably faster than the main part of the pulse propagating with the group velocity at the carrier frequency.

© 1988 Optical Society of America