Laser & Optoelectronics Progress, Volume. 56, Issue 14, 140501(2019)
Measurement of Topological Charges for Vortex Beams using Gradually-Changing-Period Annular Gratings
Measurement of topological charges (TC) for vortex beams is a key technology for the practical application of vortex beams. Herein, combining the gradual change of the gradually-changing-period grating with the complete symmetry of the annular grating, a new type of gradually-changing-period annular grating for measuring higher-order TC of vortex beams is developed by optimizing the structure of the ring grating with an additional periodic gradient. Numerical and experimental results demonstrate that a far-field diffraction pattern is formed by collimating the vortex beam onto the ring grating. The results demonstrate that the variation of the patterns accurately corresponds to the orbital angular momentum states of the vortex beams. Consequently, the number of TCs measured in the experiment is ±30. It provides a new measurement method for vortex beams.
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Wenkang Zou, Chunyong Yang, Jin Hou, Hao Long, Shaoping Chen. Measurement of Topological Charges for Vortex Beams using Gradually-Changing-Period Annular Gratings[J]. Laser & Optoelectronics Progress, 2019, 56(14): 140501
Category: Diffraction and Gratings
Received: Jan. 8, 2019
Accepted: Feb. 19, 2019
Published Online: Jul. 12, 2019
The Author Email: Yang Chunyong (cyyang@mail.scuec.edu.cn)