Wigner Rotations in Laser Cavities

The Wigner rotation is a key word in many branches of physics, chemistry and engineering sciences. It is a group theoretical effect resulting from two Lorentz boosts. The net effect is one boost followed or preceded by a rotation. This rotation can therefore be formulated as a product of three boosts. In relativistic kinematics, it is a rotation in the Lorentz frame where the particle is at rest. This rotation does not change its momentum, but it rotates the direction of the spin. The Wigner rotation is not confined to relativistic kinematics. It manifests itself in physical systems where the underlying mathematics is the Lorentz group. It is by now widely known that this group is the basic scientific language for quantum and classical optics. It is shown that optical beams perform Wigner rotations in laser cavities.