Paraxial spin-orbit beams of light-a perspective [Invited].

This paper provides a perspective on paraxial spin-orbit laser beams with a nonuniform phase-polarization structure embedded with C-point and L-line polarization singularities and surrounding lemon, star, and monstar polarization topologies. The spin and orbital angular momenta of the light beam are manipulated independently or together to produce spin-orbit light beams with these polarization features. Paraxial spin-orbit beams with topological features are generated using readily available optical components, including, as demonstrated in our group, reflection at a single and multilayer dielectric interface, propagation through an optical fiber, an optical crystal, a GRIN rod, and in two- and three-beam interferometers. Compared with uniformly polarized laser beams, spin-orbit beams offer significant experimental advantages, enabling sensitive, novel (to our knowledge) approaches to measure weak anisotropy effects in dielectric and magneto-optic media, as well as in microscopy and metrology. The generation of spin-orbit beams using off-the-shelf optical components is expected to accelerate their development and use, further enriching this emerging area of optics research.