Mechanical Equivalence Of Spin And Orbital Angular Momentum Of Light: An Optical Spanner

Simpson, N., Dholakia, K., Allen, L. and Padgett, M. (1997) Mechanical Equivalence Of Spin And Orbital Angular Momentum Of Light: An Optical Spanner. Optics Letters, 22(1), pp. 52-54. (doi: 10.1364/OL.22.000052)

Abstract

We use a Laguerre-Gaussian laser mode within an optical tweezers arrangement to demonstrate the transfer of the orbital angular momentum of a laser mode to a trapped particle. The particle is optically confined in three dimensions and can be made to rotate; thus the apparatus is an optical spanner. We show that the spin angular momentum of +/- (h) over bar per photon associated with circularly polarized light can add to, or subtract from, the orbital angular momentum to give a total angular momentum. The observed cancellation of the spin and orbital angular momentum shows that, as predicted, a Laguerre-Gaussian mode with an azimuthal mode index l = 1 has a well-defined orbital angular momentum corresponding to (h) over bar per photon.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Padgett, Professor Miles
• Authors: Simpson, N., Dholakia, K., Allen, L., and Padgett, M.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Optics Letters
• Journal Abbr.: Opt. Lett.
• ISSN: 0146-9592