THE REFLECTION OF LIGHT BY PLANAR STRATIFIED MEDIA - THE GROUPOID OF AMPLITUDES AND A PHASE THOMAS PRECESSION

The reflection coefficient of light on stratified plana structures can be obtained by postulating the use of a complex generalization of Einstein's addition theorem for parallel velocities. The algebraic properties of the 'composition law of amplitudes' show that the set of all complex amplitudes of the electromagnetic field in heterostructures forms a weakly associative-commutative groupoid. The first concrete application of this abstract concept was found only in 1988 in special relativity. This work exhibits another example in a quite different field of physics. It also puts into evidence that the 'phase rotation' of light in stratified planar structures is to be considered as a 'Thomas rotation'.