Development of off-axis spiral phase mirrors for generating optical vortices in a range of millimeter waves

• Main Authors: Goto, Y. (Author), Kobayashi, S. (Author), Kubo, S. (Author), Okada, K. (Author), Tsujimura, T.I (Author)
• Format: Article
• Language: English
• Published: American Institute of Physics Inc. 2022
• Subjects: article; Gaussian beams; human tissue; information retrieval; Low-power tests; Mechanical machining; Millimeter waves; Mirrors; Off-axis; Optical vortex beam; Optical vortices; radiofrequency; Reflected waves; Spiral phase; Topological charges; Topology; Vortex beams; Vortex flow; Vortex properties
• Online Access: View Fulltext in Publisher

 In this paper, we report the development of off-axis spiral phase mirrors that can be used to generate optical vortices from a range of millimeter waves. An obliquely incident Gaussian beam is reflected from a spiral phase mirror and is converted into an optical vortex beam with a desired topological charge. The mirrors were fabricated by mechanical machining. The designed vortex properties of reflected waves were investigated experimentally by using a low-power test, where the designed topological charge was verified based on the interference pattern between a vortex beam and a Gaussian-like beam. The designed topological charge was also estimated by using a phase retrieval method specialized for a vortex beam. These off-axis spiral phase mirrors can be used for propagation experiments of radio frequency waves with helical wavefronts in magnetized plasma. © 2022 Author(s).