Peculiarities of surface plasmon excitation in amplifying Kretschmann structure: Correct wavelength-scale analysis by the method of single expression

Traditional Kretschmann structure with dielectric covering layer of different thickness is analysed numerically by the method of single expression. Covering layers of some hundred nanometers exhibit waveguiding features and their excitation is possible at angles less than angle of surface plasmon excitation. Inclusion of gain in a covering layer is analysed and compensation of intrinsic loss in a metallic layer is discussed. The minimal value of gain for loss compensation needs the first waveguide-mode of a covering layer. This waveguiding-mode is a candidate in application for optical interconnects.