title: Average energy flow of optical pulses in dispersive media
abstract: The arrival time of a light pulse at a point in space is defined using a time expectation integral over the Poynting vector. The delay between pulse arrival times at two distinct points is shown to consist of two parts: a spectral superposition of group delays (inverse of group velocity) and a delay due to spectral reshaping via absorption or amplification. The result provides a context wherein group velocity is always meaningful even for broad band pulses and when the group velocity is superluminal or negative. The result imposes luminality on sharply defined pulses.
authors.affiliation: Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA.
authors.initials: J
authors.lastname: Peatross
authors.initials: SA
authors.lastname: Glasgow
authors.initials: M
authors.lastname: Ware