Abstract

The uniform asymptotic description of the propagation of an input Gaussian modulated harmonic signal of fixed angular frequency ω_c and initial pulse width T into the half-space z > 0 that is occupied by a single resonance Lorentz medium is described. The asymptotic theory shows that the propagated field can be expressed solely in terms of a generalized Sommerfeld and Brillouin precursor field structure. If the applied signal frequency ω_c is either below or near the medium resonance frequency, the propagated field is found to be dominated by the generalized Brillouin precursor field, while if ω_c is well above the medium resonance frequency it is dominated by the generalized Sommerfeld precursor field. The resultant pulse distortion in the dispersive medium is shown to be due solely to the manner in which the initial Gaussian pulse envelope spectrum modifies the precursor field amplitude. Finally, the frequency dependence of the pulse velocity in the single resonance Lorentz medium is described.

© 1989 Optical Society of America