We study the angular momentum (AM) of the arbitrary superposition of counterpropagating paraxial beams that have the same magnitude of the wavenumber. We derive compact analytical expressions for the total AM in a transverse cross section (linear AM density) and the total AM flux through the cross section. We demonstrate that whereas for the time-averaged linear AM density its separation into the spin and orbital parts is not, generally, observed, the total time-averaged AM flux is separated into well-identifiable spin and orbital constituents. Moreover, we show that such a flux is also naturally separated into the fluxes of forward- and backward-propagating beams.
© 2008 Optical Society of America
Original Manuscript: September 4, 2007
Manuscript Accepted: January 7, 2008
Published: February 11, 2008
Constantine N. Alexeyev, Maxim A. Yavorsky, and Vladlen G. Shvedov, "Angular momentum flux of counterpropagating paraxial beams," J. Opt. Soc. Am. A 25, 643-646 (2008)