Stopping light in an active medium

Abstract

On the basis of work done by Lorentz force and Maxwell's equations, energy conversion relationships of electromagnetic fields in the dispersive and absorptive media are analyzed. Then new definitions of stored and lossy energy densities are proposed, respectively. Furthermore, it is predicted that light may stop steadily in an active medium when both real part of impedance and imaginary part of wave vector equal zero, which corresponds to a case that time-dependent Poynting vector shift forward and then turn backward periodically.