Dynamic interferometry measurement of orbital angular momentum of light

TL;DR

This paper introduces a simple, low-cost dynamic interferometry method using a double-slit setup to measure the orbital angular momentum of light beams, capable of handling large topological charges.

Contribution

The paper presents a novel, cost-effective interferometry technique employing a scanning double-slit to accurately measure the OAM of light, including high topological charges.

Findings

Effective measurement of OAM with large topological charges

Interference pattern changes correlate with OAM phase differences

Method is simple and adaptable for various OAM beams

Abstract

We present a dynamic interferometry to measure the orbital angular momentum (OAM) of beams. An opaque screen with two air slits is employed, which can be regarded as the Youngs double-pinhole interference. When the OAM beams with an annular intensity distribution vertically incident, the far-field interference patterns depend on the phase difference of the light in the two pinholes. We scan the angle between the two slits, the output intensity at center changes alternatively between darkness and brightness. Utilizing this characteristic, we can measure the OAM of light. This scheme is very simple and low-cost. In addition, it can measure very large topological charge of OAM beams due to the continuously scanning.