2017年6月8日
Focusing light with orbital angular momentum by circular array antenna
Optics Express
- ,
- ,
- 巻
- 25
- 号
- 12
- 開始ページ
- 13728
- 終了ページ
- 13728
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1364/oe.25.013728
- 出版者・発行元
- The Optical Society
We experimentally demonstrated focusing of light with orbital angular momentum (OAM) using an 8-element circular array of linear antennas A spiral phase plate was used to generate a vortex beam with an OAM of (h) over bar in the terahertz (THz) frequency region. We used THz near-field microscope to directly measure the phase vortex. A beam profile with a center dark spot and 2 pi phase rotation was observed in the small center gap region of the circular array antenna after the vortex beam excitation. The beam size is reduced by a factor of 3.4 +/- 0.2. Half-wave resonance of the antenna element is responsible for the focusing function, indicating the scalability of this method to other frequency regions. This method will enable deep subwavelength focusing of light with OAM and eliminate the obstacle for the observation of the dipole forbidden transition with finite OAM of the vortex beam. (C) 2017 Optical Society of America
- リンク情報
- ID情報
-
- DOI : 10.1364/oe.25.013728
- ISSN : 1094-4087
- ORCIDのPut Code : 90858164
- Web of Science ID : WOS:000403942300082