  We have considered theoretically the waveguide properties of a plane
two-layered waveguide, whose one layer is a usual magnetodielectric
(forward-wave medium), but another one is a slab of so-called backward-wave
material (BW-material), whose both permittivity and permeability are negative.
We have analyzed the properties of eigenwaves in this waveguide. In particular,
it was found that there exist waves of both TE and TM polarizations, whose
fields decay exponentially from the interface of the two slabs inside both
layers, and their slow-wave factor tends to infinity at small frequencies.
Thus, this waveguiding system supports super-slow waves with extremely short
wavelengthes, as compared to the free-space wavelength and the cross section
size. Other peculiarities of the spectrum are also discussed.
