  We discuss the properties of the transmission function in the k-space for a
generic multi-layered structure. In particular we analytically demonstrate that
a transmission greater than one in the evanescent spectrum (amplification of
the evanescent modes) can be directly linked to the guided modes supported by
the structure. Moreover we show that the slope of the phase of the transmission
function in the propagating spectrum is inversely proportional to the ability
of the structure to compensate the diffraction of the propagating modes. We
apply these findings to discuss several examples where super-resolution is
achieved thanks to the simultaneous availability of the amplification of the
evanescent modes and the diffraction compensation of the propagating modes.

Optics