Measuring the complex orbital angular momentum spectrum and spatial mode decomposition of structured light beams

Abstract

Light beams carrying orbital angular momentum are key resources in modern\nphotonics. In many applications, the ability of measuring the complex spectrum\nof structured light beams in terms of these fundamental modes is crucial. Here\nwe propose and experimentally validate a simple method that achieves this goal\nby digital analysis of the interference pattern formed by the light beam and a\nreference field. Our approach allows one to characterize the beam radial\ndistribution also, hence retrieving the entire information contained in the\noptical field. Setup simplicity and reduced number of measurements could make\nthis approach practical and convenient for the characterization of structured\nlight fields.\n