Resumen:
E}ectro~agnetic absorption of light in superconducting Kondo alloys and in superconducting
alloys with strong electron —magnetic-impurity interaction is discussed without recourse to the
quasiparticle approximation. The electromagnetic (em) absorption of light defined in terms of
Shiba-Rusinov equilibrium one-particle Green's functions is examined in the limit of small
momentum transfer (London limit) and in the Eliashberg approximation of neglecting the
momentum dependence of the electronic self-energy. For the specific case of the Fe-In alloy
numerical calculations have been made for the ratio of em absorption in the superconducting
and normal states as a function of reduced frequency and temperature for different impurity
concentrations.