Volume 81, Number 6, March 2008
Article Number 67005
Number of page(s) 5
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
Published online 29 February 2008
EPL, 81 (2008) 67005
DOI: 10.1209/0295-5075/81/67005

Poynting's theorem and energy conservation in the propagation of light in bounded media

F. Richter, M. Florian and K. Henneberger

Universität Rostock, Institut für Physik - 18051 Rostock, Germany

received 18 December 2007; accepted in final form 2 February 2008; published March 2008
published online 29 February 2008

Starting from the Maxwell-Lorentz equations, Poyntings theorem is reconsidered. The electromagnetic energy flux vector is introduced such that it can be related to the kinetic energy of the matter subsystem. Conservation of the total energy follows. In our discussion, the microscopic nature of media is represented exactly by susceptibility functions, which do not necessarily have to be known. On this footing, it can be shown that energy conservation in the propagation of light through bounded media is ensured by Maxwell's boundary conditions alone, even for some frequently used approximations. This is demonstrated for approaches using additional boundary conditions and the dielectric approximation in detail, the latter of which suspected to violate energy conservation for decades.

78.20.-e - Optical properties of bulk materials and thin films.
03.50.De - Classical electromagnetism, Maxwell equations.
71.35.Cc - Intrinsic properties of excitons; optical absorption spectra.

© EPLA 2008