Temporal equivalent of the Brewster angle

Can the Brewster angle have a temporal equivalent? Here, the authors exploit time-dependent metamaterials to propose the idea of such a temporal analog. When the permittivity of the medium rapidly changes in time from an isotropic to anisotropic value, the backward wave may be absent for such an angle of incidence. A closed-form mathematical expression, along with numerical simulations, for this temporal analog of the Brewster angle is provided.