Some perspectives on the modes guided by negative-permittivity slabs

In this paper we highlight the early pioneering work of Tamir and Oliner on analyzing the spectrum of waves supported by a negative permittivity slab. We show how this work relates to recent research on metamaterial slabs. We also discuss the complex modes supported by such slabs in relation to recent work on positive-index/negative-index couplers and how a single complex mode satisfies power conservation.