From Maxwell's equations, we compute the speed and the direction of propagation of active power refracted from air into a negative index material. We prove, both analytically and numerically that the power may refract positively even if phase fronts refract negatively. Considerations on the usage of ray optics in problems involving negative index materials are drawn.
© 2005 Chinese Optics Letters
Lorenzo Bolla, Michele Midrio, and Carlo G. Someda, "Energy flow in negative index materials," Chin. Opt. Lett. 2, 428-430 (2004)