The Kullback–Leibler Divergence evolution of randomized electromagnetic field

The statistical properties of randomized electromagnetic field have been investigated by simulating the scattering of electromagnetic waves by random media (RMs). In the viewpoint of a theoretical requirement, the probability density function of perfectly randomized field satisfies the zero-mean circular Gaussian (ZMCG) statistics. We find that Kullback–Leibler Divergence (KLD) can quantitatively evaluate the randomness of an electromagnetic field to improve the design of RMs. There are two types of RMs which can efficiently randomize the electromagnetic waves only by monotonically increasing the permittivity of scatterers. When both the permittivity and total number of scatterers are fixed, KLD always have a limitation in any practical RM, which are characterized by a plateau on the evolutionary curve.