Negative extinction in one-dimensional scattering

The energy/sec transmitted and reflected by a flat dielectric slab embedded in an absorbing host medium was calculated for normal plane wave incidence. It was found that the outgoing scattered energy/sec differs from the incoming energy/sec carried by the incident beam. This apparent energy nonconservation is compensated exactly by the energy/sec of the standing wave interference of the incoming plane wave with the outgoing reflected wave evaluated at the surface of the slab. This interference energy/sec, also known as extinction for this one-dimensional scattering situation, oscillates between positive and negative values as a function of slab thickness, in analogy to a similar effect recently predicted for scattering by a dielectric sphere embedded in an absorbing host medium.