Electromagnetic Tunneling in Lossless Trilayer Stacks Containing Single-Negative Metamaterials
We analyze the transverse-electric wave propagation through lossless trilayer stacks containing single-negative (SNG) materials in which only one of the two material constants, permittivity (epsilon) or permeability (mu), is negative. We consider the following combinations: ENG/MNG/ENG, ENG/DPS/MNG, DPS/ENG/DPS, and ENG/DPS/ENG, where ENG refers to epsilon-negative, MNG to mu-negative, and DPS to double-positive media. The transfer matrix formalism is applied. Although the waves are evanescent in the SNG media, combining the SNG layers or the SNG and DPS layers, leads to some unusual features, such as the complete tunneling. Since the symmetrical trilayer is equivalent to a single homogeneous layer, the complete tunneling conditions are easily predicted analytically for the trilayer stacks, and we show that in most of cases, they are rather well applicable to the respective bilayer stacks. The field and the Poynting vector distributions are studied in different trilayers and, in some cases, in the respective bilayers. In particular, we show that the complete tunneling is facilitated theoretically in the electrically thin stacks. Similar results could be obtained for the transverse-magnetic waves and the respective dual combinations by using the duality principle.