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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.

The random intensity distribution observed due to the propagation of a coherent beam of light through a scattering medium is known as a speckle pattern. The interaction of the speckles with a birefringent crystal, here, YVO4 results in the e-ray and o-ray speckles. It is observed that the eray and o-ray speckles experience an angular shift with the rotation of the crystal and the shift depends on the rotation angle of the crystal. It is also found that the rate of the shift is different for e-ray and o-ray speckles, and is independent of the topological charge of the beam incident on the scattering medium. The observed rate of shift of the speckle pattern is found to be same as that of the e-ray and o-ray beams. It is experimentally demonstrated that the rotation of a birefringent crystal can be tracked very accurately from the speckle shift measurement.

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.