title: Orbital angular momentum of Laguerre-Gaussian beams beyond the paraxial approximation.
abstract: We derive a full field solution for Laguerre-Gaussian beams consistent with the Helmholtz equation using the angular spectrum method. Field components are presented as an order expansion in the ratio of the wavelength to the beam waist, f=λ/(2πw₀), which is typically small. The result is then generalized to a beam of arbitrary polarization. This result is then used to reproduce the signature angular momentum properties of Laguerre-Gaussian beams in the paraxial limit. The subsequent higher-order term is similarly obtained, which does not display a clear separation of orbital and spin angular momentum components.
authors: Department of Physics, Yale University, New Haven, Connecticut 06520-8120, USA. alexander.cerjan@yale.edu
authors: Alexander
authors: A
authors: Cerjan
authors: Charles
authors: C
authors: Cerjan