Chinese Optics Letters, Volume. 20, Issue 11, 110501(2022)

Measuring the topological charge of optical vortices with a single plate

Jingyin Zhao1,2,3, Yunxia Jin1,3,4、*, Fanyu Kong1,3, Dongbing He1,3, Hongchao Cao1,3, Wang Hao1,2,3, Yubo Wu1,2,3, and Jianda Shao1,3,4,5
Author Affiliations
  • 1Thin Film Optics Laboratory, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
  • 2Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
  • 3Key Laboratory of High Power Laser Materials, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
  • 4CAS Center for Excellence in Ultra-Intense Laser Science, Chinese Academy of Sciences, Shanghai 201800, China
  • 5Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China
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    Measuring the topological charge (TC) of optical vortex beams by the edge-diffraction pattern of a single plate is proposed and demonstrated. The diffraction fringes can keep well discernible in a wide three-dimensional range in this method. The redundant fringes of the diffracted fork-shaped pattern in the near-field can determine the TC value, and the orientation of the fork tells the handedness of the vortex. The plate can be opaque or translucent, and the requirement of the translucent plate for TC measurement is analyzed. Measurement of TCs up to ±40 is experimentally demonstrated by subtracting the upper and lower fringe numbers with respect to the center of the light. The plate is easy to get, and this feasible measurement can bring great convenience and efficiency for researchers.

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    1. Introduction

    In 1992, Allen et al. firstly, to the best of our knowledge, demonstrated a helical phase structure of light with wavefront singularities carrying orbital angular momentum (OAM)[1]. Such optical vortex (OV) beams characterized by the phase factor exp(ilθ), where l donates the OAM state or the topological charge (TC), and θ is the azimuthal angle, have been widely applied in various areas, including optical tweezers[2], optical trapping[3], optical communication[4], and quantum information technology[5]. Most of these applications require a specific TC. As a consequence, the determination of TCs is of crucial importance.

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    Jingyin Zhao, Yunxia Jin, Fanyu Kong, Dongbing He, Hongchao Cao, Wang Hao, Yubo Wu, Jianda Shao. Measuring the topological charge of optical vortices with a single plate[J]. Chinese Optics Letters, 2022, 20(11): 110501

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    Paper Information

    Category: Diffraction, Gratings, and Holography

    Received: May. 12, 2022

    Accepted: May. 31, 2022

    Posted: Jun. 1, 2022

    Published Online: Jun. 29, 2022

    The Author Email: Yunxia Jin (yxjin@siom.ac.cn)

    DOI:10.3788/COL202220.110501

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