A coupler is a device that allows interconversion of angular momentum of the optical beam among spin and orbital parts, without absorbing any angular momentum. In this paper, we demonstrate that a q -plate with q = 1 can act as a coupler for any of the polarization distribution that can be represented by a point on a Poincare sphere (PS), or on a higher-order PS, or on a hybrid-order PS. A q -plate with any q -value can act as a coupler for polarization distribution that can be represented by an equatorial point on any of these spheres. It is also possible to find a q -plate with an appropriate q -value that can act as a creation or annihilation operator that raises or lowers the polarization singularity index. The q -plate being a coupler and made of half-wave plate segments, the singularity index change is concomitant with the helicity inversion of C-points. Interconversion of bright and dark C-points is possible by using a q -plate.

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In this paper, we propose a method for the generation of a two-dimensional spin-orbit beam lattice using a Dammann grating. A Dammann grating is fabricated and is illuminated by ellipse field/vector filed singular beam that contains a polarization singularity. Since, Dammann grating is used to produce equal-intensity light spots, each of the spin-orbit beams in the lattice has equal intensity distribution. Interestingly, they also have the same polarization distribution as that of the input light. Unlike the interferometric methods of lattice generation, the diffractive method proposed here produces lattices of the same index singularities. Simulation and experimental results are provided to demonstrate the concept.

A method of generation of polarization singularity lattice is presented. Singularities are produced at discrete points along the line of phase discontinuity by giving different circular phase ramp in different regions of wavefront.