A general expression for the electromagnetic energy density in a lossy dispersive medium, applicable for a field having a narrow temporal frequency bandwidth, is derived and compared with exact results for an example dielectric constant. Consequently, the possibility of negative time-averaged stored field energy is shown to have physical meaning. This observation is of interest in the study of dispersive metamaterials, such as those which can exhibit a negative refractive index.
© 2010 Optical Society of America
Original Manuscript: February 18, 2010
Manuscript Accepted: March 4, 2010
Published: May 12, 2010
Kevin J. Webb and Shivanand, "Electromagnetic field energy in dispersive materials," J. Opt. Soc. Am. B 27, 1215-1220 (2010)