  We propose a single phase-only optical element that transforms different
orbital angular momentum (OAM) modes into localized spots at separated angular
positions on a transverse plane. We refer to this element as an angular lens
since it separates out OAM modes in a manner analogous to how a converging lens
separates out transverse wave-vector modes at the focal plane. We also simulate
the proposed angular lens using a spatial light modulator and experimentally
demonstrate its working. Our work can have important implications for OAM-based
classical and quantum communication applications.
