Determination of the total angular momentum of a paraxial beam

The multipolar solution of the electromagnetic field is useful in light-matter interactions. Here is presented a method to control the superpositions of multipolar electromagnetic fields using paraxial beams. This is applied to orbital angular momentum paraxial modes, which allow us to calculate their total angular momentum. This quantity plays an important role in the control of electronic transitions in atoms and molecules. The results here can easily be extended to highly focused laser beams.