To the analyticity of the effective refractive index

Resumo

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.