Measurement of the rotational frequency shift imparted to a rotating light beam possessing orbital angular momentum

Abstract

We observe the frequency shift, lΩ, imparted to a mm-wave beam with an orbital angular momentum of lħ per photon, when the beam is rotated at angular frequency Ω. We show that thisshift, and those found in a number of experiments on the rotation of circularly polarized beams, are special cases of the rotational frequency shift recently predicted by Bialynicki-Birula and Bialynicka-Birula. The measurement also explicitly confirms a theoretical prediction by Nienhuis. © 1998 The American Physical Society.