The evanescent waves in geometrical optics and the mixed hyperbolic–elliptic type systems
The evanescent waves in geometrical optics and the mixed hyperbolic–elliptic type systems
In this article we describe the generation of the evanescent waves which are present in the rarer medium at total reflection by using a mixed-type system, the Ludwig system, which leads naturally to consider a complex-valued phase. The Ludwig system is derived from the Helmholtz equation by using an appropriate …