Vortex beams are structured light fields with a helical phase of the form exp (ilϕ) that carries an optical angular momentum (OAM) of lℏ per photon. Such beams typically have a ring-shaped intensity with a radius that varies with l. Perfect vortex (PV) beams are designed to have a radius that is approximately uniform over a certain OAM range. Here, we report how spatial coherence can be used to maintain a fixed ring shape over a larger propagation distance and for a greater OAM range than is possible for fully coherent vortex beams. Our work is relevant for the application of PV beams in areas such as trapping, tweezing, and optical communications.
Bibliographical noteFunding Information:
This work was supported by the National Key Research and Development Program of China (Grant No. 2019YFA0705000); the National Natural Science Foundation of China (Grant Nos. 11804198, 91750201, 11525418, and 11974218); the Shandong Provincial Natural Science Foundation of China (Grant No. ZR2019BA030); the Innovation Group of Jinan (Grant No. 2018GXRC010); the Local Science and Technology Development Project of the Central Government (Grant No. YDZX20203700001766); and the China Postdoctoral Science Foundation (Grant No. 2018M642690). T.D.V. acknowledges funding by The Dutch Research Council (NWO) under project P19–13 “Optical wireless super highways.”
© 2021 Author(s).