To the analyticity of the effective refractive index

摘要

The possibility to describe the plane-wave propagation in a periodic layered medium in terms of effective parameters is considered. It is shown that, for a finite system, the effective refractive index can be determined with the help of the amplitude transmission coefficient. The analyticity of the effective refractive index as a function of frequency is studied. It is shown that the effective refractive index is an analytic function of frequency, and the Kramers-Kronig relations, which connect the real and imaginary parts, are found.