Abstract
Two models of metal–dielectric composite media are used to study the optical properties of their active (amplifying) components under conditions of compensation for the absorption of external electromagnetic radiation appearing due to the presence of metal inclusions. It is shown that the electrostatic approximation for describing the concentrated composite media (a metal nanosphere in a dielectric shell) and bulk composite media (a system of metal nanocylinders in a dielectric matrix) can be applied only in a small range of geometrical and optical parameters. Precise electrodynamic calculations give much smaller gains in the active component required to compensate for absorption, which can be useful for developing 'transparent' composite materials with unique optical properties or 'invisible' composite particles.