Emission of orbital angular momentum based on spoof localized surface plasmons

Youfei Zhang, Qingle Zhang, Chi Hou Chan, Erping Li, Jianming Jin, Haogang Wang

Research output: Contribution to journalArticlepeer-review

Abstract

An approach to producing the orbital angular momentum (OAM) based on spoof localized surface plasmons (spoof LSPs) in microwave frequencies is demonstrated both theoretically and experimentally. The fundamental and high-order modes of spoof LSPs occur when a textured metallic surface is excited with a microstrip line. Two orthogonal modes of spoof LSPs with +90° or −90° phase retardation are superimposed, resulting in a OAM-vortex mode. In the proposed design, two separate feeding ports are employed to excite the orthogonal resonant modes simultaneously, and a hybrid coupler is used to provide the required ±90° phase retardation. By loading a circularly arranged dipole array on the spoof LSPs, the confined surface waves of the spoof LSPs can be converted into radiated vortex waves. To verify this idea, an OAM-mode emitter with indices of ±3 is fabricated and measured. Experimental near-field distributions and far-field radiation patterns show excellent agreement with the simulated results.

Original languageEnglish (US)
Pages (from-to)5735-5738
Number of pages4
JournalOptics Letters
Volume44
Issue number23
DOIs
StatePublished - Dec 1 2019

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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