  Time-varying metamaterials are artificial materials whose electromagnetic
properties change over time. In earlier studies, the equivalent reflection and
transmission coefficients at a temporal interface have been derived. Here, we
extend the study to a temporal slab, i.e., a uniform homogeneous medium that is
present in the space for a limited time. We derive the transmission and
reflection coefficients for a metamaterial temporal slab as a function of the
refractive indices and application time. Similarly to the role played by the
electrical thickness for spatial slabs, we show that the response of the
temporal slab can be controlled through the application time. The preliminary
results reported here may pave the way to several novel devices based on
temporal discontinuities.
