“Superlight” Propagation of Electromagnetic Pulses in a Resonant-Absorbing Gas Medium

Abstract: Based on the calculation of the Fourier integral directly and without simplifying assumptions, the analysis of the process of passage of terahertz pulses with a hat-shaped envelope and Van Bladel envelope through a layer of a resonant-absorbing medium described by the Drude–Lorentz model is carried out. It is shown that until the end of the time interval prescribed by the Maxwell equations, there is no radiation at the exit from the layer, i.e., the Fourier integral does not contain the effect of “superluminal” propagation of an electromagnetic pulse through a resonantly absorbing medium. An alternative interpretation of the shift to the beginning of the pulse of the envelope maximum emerging from the radiation layer at small optical depths (~1) of the layer at the resonant frequency of the medium is proposed.