Spin-Orbit Coupling in Quasi-Monochromatic Beams

We investigate the concept that the value of the spin-orbit coupling is the energy efficiency of energy transfer between orthogonal components. The energy efficiency changes as the beam propagates through the crystal. For a fundamental Gaussian beam, its value cannot exceed 50%, while the energy efficiency for Hermite-Gaussian and Laguerre-Gaussian beams of higher orders of the complex argument can reach a value close to 100%. For Hermite-Gauss and Laguerre-Gauss beams of higher orders of real argument, the maximum energy efficiency can only slightly exceed 50%. It is shown that zero-order Bessel-Gauss beams are able to achieve an energy efficiency close to 100% when generating an axial vortex in the orthogonal component in both monochromatic and polychromatic light, while for a polychromatic Laguerre-Gauss or Hermite-Gauss beam of a complex argument, the energy efficiency reduced to a value not exceeding 50%. The spin angular momentum is compensated by changing the orbital angular momentum of the entire beam, which occurs as a result of the difference in the topological charge of the orthogonally polarized component by 2 units.

Automated summary

We investigated the value of spin-orbit coupling as the energy efficiency of energy transfer between orthogonal components. The energy efficiency changes as the beam propagates through the crystal. For different types of beams, such as Gaussian, Hermite-Gaussian, Laguerre-Gaussian, the energy efficiency varies, with higher orders of complex argument beams having a higher efficiency. We found that zero-order Bessel-Gauss beams can achieve close to 100% energy efficiency when generating an axial vortex in the orthogonal component, while polychromatic Laguerre-Gauss or Hermite-Gauss beams have a reduced energy efficiency not exceeding 50%.