Separation of spin and orbital angular coherence momenta in the second-order coherence theory of vector electromagnetic fields

Opt Lett. 2007 Sep 15;32(18):2656-8. doi: 10.1364/ol.32.002656.

Abstract

In analogy with the separation of the total optical angular momentum into a spin and an orbital part in electrodynamics, we introduce a new concept of spin and orbital angular coherence momenta into the general coherence theory of vector electromagnetic fields. The properties of the newly introduced spin and orbital angular coherence momenta are investigated through the decomposition of the total coherence angular momentum into the sum of these two components, and their separate conservations have been derived for what is believed to be the first time.