We derive a formal description of local light-ray rotation in terms of complex refractive indices. We show that Fermat’s principle holds, and we derive an extended Snell’s law. The change in the angle of a light ray with respect to the normal of a refractive index interface is described by the modulus of the refractive index ratio; the rotation around the interface normal is described by the argument of the refractive index ratio.
© 2009 Optical Society of America
Original Manuscript: September 25, 2008
Revised Manuscript: November 25, 2008
Manuscript Accepted: December 15, 2008
Published: January 30, 2009
Bhuvanesh Sundar, Alasdair C. Hamilton, and Johannes Courtial, "Fermat's principle and the formal equivalence of local light-ray rotation and refraction at the interface between homogeneous media with a complex refractive index ratio," Opt. Lett. 34, 374-376 (2009)