Electric area conservation rule and the validity of some models of subcycle pulse propagation

The validity issues of some approximations widely used to describe subcycle pulse propagation in various non-magnetic media are addressed. As the validity criteria we apply the fundamental electric area conservation rule, which directly follows from Maxwell's equations in the 1D case. The general relations are derived for the possible values of the electric area in different media. It is shown that several theoretical models do not in general comply with the electric area conservation rule, which implies their limited applicability to correctly describe the subcycle pulse interaction with media. Therefore, any results obtained using such models cannot be taken as scientifically valid and meaningful.