Abstract

In this Letter, we investigate the Fresnel diffraction of vortex beams from a phase plate and propose a novel (to the best of our knowledge) method to determine the fractional part of the topological charge of vortex beams. When a vortex beam with a fractional topological charge illuminates the edge region of a transparent plate, the visibility of the diffraction pattern on two sides of the beam is different. Rotation of the phase plate changes the visibility on the left and right sides of the beam, periodically. By measuring three consecutive angles of the minimum visibilities, the fractional part of the topological charge is obtained. The proposed method is verified experimentally and is shown to be independent of the phase plate and vortex beam parameters. The precision of the method is obtained better than 0.01.

© 2020 Optical Society of America

Fractional topological charge measurement through optical correlation

Allarakha Shikder, Jyoti Bikash Mohapatra, and Naveen K. Nishchal
Opt. Lett. 49(8) 2017-2020 (2024)

Measurement of the integer and fractional topological charge of optical vortex beams by using crossed blades

Sanaz Foroughi Dehnoei and Saeed Ghavami Sabouri
Appl. Opt. 62(13) 3409-3415 (2023)

Intersecting of circular apertures to measure integer and fractional topological charge of vortex beams

Negin Daryabi and Saeed Ghavami Sabouri
Opt. Express 31(17) 28459-28469 (2023)

Highly multimodal structure of high topological charge extreme ultraviolet vortex beams

F. Sanson, A. K. Pandey, I. Papagiannouli, F. Harms, G. Dovillaire, E. Baynard, J. Demailly, O. Guilbaud, B. Lucas, O. Neveu, M. Pittman, D. Ros, M. Richardson, E. Johnson, W. Li, Ph. Balcou, and S. Kazamias
Opt. Lett. 45(17) 4790-4793 (2020)

Measuring the topological charge of terahertz vortex beams with a focal hyperbolic lens

Yongqiang Yang, Liting Niu, Zhengang Yang, and Jinsong Liu
Appl. Opt. 59(15) 4685-4691 (2020)