  We develop an analytical approach based on the Rytov-Leontovich boundary
conditions to study light field modes in the nano planar waveguides. The
analytical results thus obtained demonstrate new conditions for optical low
loss surface plasmon-polariton modes in the planar waveguides with
dielectric-metamaterial interfaces. The obtained results are confirmed with
existing numerical calcultions. More general conditions for using the proposed
analytical approach to study light field in the nano waveguides are also
considered.
