Measuring mode indices of a partially coherent vortex beam with HBT type experiment

TL;DR

This paper demonstrates an efficient experimental method using the Hanbury Brown and Twiss effect to measure mode indices of partially coherent vortex beams, with potential applications in astronomy and free space communication.

Contribution

It introduces a practical and robust technique to measure vortex beam mode indices via the HBT effect, addressing previous measurement challenges.

Findings

HBT effect can effectively measure vortex mode indices.

Spatial coherent width influences the CCF of PCV beams.

The method is applicable to astronomy and free-space communication.

Abstract

It is known that the cross-correlation function (CCF) of a partially coherent vortex (PCV) beam shows a robust link with the radial and azimuthal mode indices. However, the previous proposals are difficult to measure the CCF in practical system, especially in the case of astronomical objects. In this letter, we demonstrate experimentally that the Hanbury Brown and Twiss effect can be used to measure the mode indices of the original vortex beam and investigate the relationship between the spatial coherent width and the characterization of CCF of a PCV beam. The technique we exploit is quite efficient and robust, and it may be useful in the field of free space communication and astronomy which are related to the photon's orbital angular momentum.