We address the general issue of resolving the wave vector in complex electromagnetic media including negative refractive media. This requires us to make a physical choice of the sign of a square root imposed merely by conditions of causality. By considering the analytic behavior of the wave vector in the complex plane, it is shown that there are a total of eight physically distinct cases in the four quadrants of two Riemann sheets.
© 2005 Optical Society of America
S. Anantha Ramakrishna and Olivier J. Martin, "Resolving the wave vector in negative refractive index media," Opt. Lett. 30, 2626-2628 (2005)