Date Published: November 24, 2014
Masud Mansuripur's Optical Physics Group researches optical-magnetic-macromolecular data storage, light-matter interaction, magneto-optical effects and the mechanical effects of light involving the exchange of linear and angular momenta between electromagnetic fields and material media.
As an example of the latter effects, the figure above shows a hollow metallic cone with an apex angle of 90 degrees, illuminated by a circularly polarized light beam. Upon reflection from the cone, the spin angular momentum of the beam is reversed. However, no angular momentum is transferred to the cone, because the reflected beam picks up an orbital angular momentum twice as large but opposite in direction to that of its spin. The figure also shows profiles of the phase and the Poynting vector in the cross-sectional plane of the reflected beam.
Light reflected from a hollow cone undergoing changes in spin and orbital angular momentum, as shown by the variation of the Poynting vector and phase in transverse plane.