Investigation of an optical vortex beam with a leaky planar waveguide

Abstract

First experimental investigation of an optical vortex beam by means of a multiple-beam interference device is reported. Launching of an optical vortex beam into a prism–film coupler (leaky-wave planar waveguide) gives high angular resolution due to the resonant excitation of a propagating leaky mode. Observation of the dark line in the cross-section of the reflected beam visualizes a narrow range of equal incident angles within an optical beam with diffraction-limited divergence. The expectations from optical ray approach and wave approach are compared with the experimental results.