We offer a convenient and dynamic method for the measurement of the orbital angular momentum of light using its distinct Fraunhofer diffraction patterns(FDPs) after passing through programmable apertures generated by a digital micromirror device (DMD). The DMD allows for a practical way of testing and centering several apertures, while minimizing movements in the setup in between measurements. We show how to extract the topological charge value, polarity, and parity from the resulting patterns, along with the limitations of each polygon shape, such as the symmetry and uniqueness issues. An experimental demonstration is also provided, confirming the expected patterns simulated using the far-field diffraction integral. This study establishes the potential speed and accuracy brought by the use of a DMD for the challenging task of characterizing the orbital angular momentum of light.

Date Published: 8 November 2018
PDF: 6 pages
Proc. SPIE 10818, Holography, Diffractive Optics, and Applications VIII, 108180U (8 November 2018); doi: 10.1117/12.2500986

Published in SPIE Proceedings Vol. 10818:
Holography, Diffractive Optics, and Applications VIII
Yunlong Sheng; Chongxiu Yu; Changhe Zhou, Editor(s)