Electromagnetic field energy in an absorptive medium with temporal and spatial dispersion

TL;DR

This paper develops general relations for electromagnetic field energy in absorptive media with dispersion, extending the Planck law to account for absorption and particle contributions.

Contribution

It introduces a bilinear form of dielectric polarizability to describe particle contributions to electromagnetic energy in absorptive media.

Findings

Derived explicit expressions for electromagnetic energy outside transparency domain.

Generalized Planck law for absorptive media.

Provided a framework for calculating energy contributions in complex media.

Abstract

General relations for electromagnetic field energy outside the transparency domain are proposed. It is shown that charged particle contribution to the energy of electromagnetic perturbations in the general case can be described in terms of a bilinear combination of the dielectric polarizability of the medium. The explicit form of such contribution is found. The relations obtained are used to generalize the Planck law to the case of an absorptive medium.