  We introduce a new method to generate and tune the optical orbital angular
momentum of a focused Gaussian beam passing through the optical superlattice
under the electro-optic effect. The orbital angular momentum (OAM) arises from
the curl of polarization in our calculation. We see that adjusting the external
electric field, the beam waist radius and the crystal length provides dramatic
variation of OAM of light across the transverse section. It is believed that
this invention will find its application in optical manipulation area.
