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Direct Measurement of the Millimeter Wave Phase Singularity with Helical Wavefront using Heterodyne Detection System at Two Spatial Points

Yuki GOTO, Shin KUBO¹⁾, Toru Ii TSUJIMURA and Toru KOBAYASHI²⁾

National Institute for Fusion Science, National Institutes of Natural Sciences, Toki 509-5292, Japan

1)

College of Engineering, Chubu University, Kasugai 487-8501, Japan

2)

Department of Applied Energy, Nagoya University, Nagoya 464-8603, Japan

(Received 27 December 2021 / Accepted 27 January 2022 / Published 18 March 2022)

Abstract

In this paper, we measured the one-dimensional phase and polarization structure of a millimeter-wave with a helical wavefront (vortex beam) using a simultaneous heterodyne detection system at two spatial points. This is a novel approach, and it provides us with the relative phase of the vortex beam. We measured the phase discontinuity of the vortex beam by scanning the one-dimensional path where an antenna passes through the optical axis. It was found that relative phases gradually increase or decrease when the antenna does not pass through the optical axis. Additionally, we measured polarization parameters, which were indefinite near the optical axis. In other words, the optical axis of the vortex beam is a singular point about the phase.

Copyright (c) 2022 The Japan Society of Plasma Science and Nuclear Fusion Research

Keywords

vortex beam, helical wavefront, phase singularity, heterodyne detection system, millimeter-wave

DOI: 10.1585/pfr.17.2401007

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