Optical momentum distributions in monochromatic, isotropic random vector fields

Titouan Gadeyne (1, 2) , Mark R Dennis (3, 4)

1 LIDYL - Laboratoire Interactions, Dynamiques et Lasers (ex SPAM)
2 ATTO - Attophysique
3 University of Birmingham [Birmingham]
4 University of Bristol [Bristol]

Abstract We investigate the decomposition of the electromagnetic Poynting momentum density in three-dimensional random monochromatic fields into orbital and spin parts, using analytical and numerical methods. In sharp contrast with the paraxial case, the orbital and spin momenta in isotropic random fields are found to be identically distributed in magnitude, increasing the discrepancy between the Poynting and orbital pictures of energy flow. Spatial correlation functions reveal differences in the generic organization of the optical momenta in complex natural light fields, with the orbital current typically forming broad channels of unidirectional flow, and the spin current manifesting larger vorticity and changing direction over subwavelength distances. These results are extended to random fields with pure helicity, in relation to the inclusion of electric-magnetic democracy in the definition of optical momenta.

Mots clés: statistical optics; optical momentum; Poynting vector; spin momentum; orbital momentum

Domaines: Physique [physics]

Titouan Gadeyne, Mark R Dennis. Optical momentum distributions in monochromatic, isotropic random vector fields. Journal of Optics, 2024, 26 (6), pp.065604. ⟨10.1088/2040-8986/ad3b14⟩. ⟨cea-04569117⟩