Angular momentum of a strongly focused Gaussian beam

@inproceedings{Nieminen2008AngularMO,
  title={Angular momentum of a strongly focused Gaussian beam},
  author={Timo A. Nieminen and Alexander B Stilgoe and Norman R. Heckenberg and Halina Rubinsztein-Dunlop},
  year={2008}
}
A circularly polarized paraxial Gaussian laser beam carries ±h̄ angular momentum per photon as spin, with zero orbital angular momentum. Focusing the beam with a rotationally symmetric lens cannot change this angular momentum flux, yet the focused beam must have spin |Sz | < h̄ per photon. The remainder of the original spin is converted to orbital angular… CONTINUE READING