Active Maxwell-Garnett composite with the unit refractive index

Optical properties of a three-dimensional composite medium consisting of an amplifying matrix with inclusion of silver nanoparticles of various shapes are investigated theoretically. Behaviour of the amplification coefficient of active component required for compensating energy dissipation at metal inclusions is studied. Results of exact electrodynamical calculations of conditions for obtaining the unit refractive index and that performed using electrostatic approximation (Maxwell-Garnett approach) are compared.