2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/217652We describe 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 to 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.3 pages, 2 figuresOpticstext