Abstract

In a passive linear medium, the principle of causality leads to the Kramers-Kronig relations. These relations relate the real and imaginary parts of dielectric permittivity through Hilbert transforms. Equivalently, there are relations between the propagation constant and absorption coefficient when a wave is propagated in such a medium. In passive random media, the real and imaginary parts of dielectric permittivity with stochastic variations also obey the Kramers-Kronig relations.

© 1986 Optical Society of America