Surface plasmon waves carry an intrinsic transverse spin angular momentum, which is locked to their propagation direction. On the other hand, helical plasmonic distributions may also carry an orbital angular momentum that is linked to the field topology. Apparently, when such a singular plasmonic mode propagates on a surface or is guided on a conic structure its helicity and the transverse spin can be coupled to the far-field spin and orbital angular momentum. We discuss the mechaism of such a coupling by using 2D and 3D guiding architetures. We analyze the coupling efficiency in each case as well as the intriguing spin-locking phenomenon occurring in our system. Finally we experimentally demonstrate the efficient beaming of a single-handed mode decorated by a desired orbital angular using accurately fabricated nanostructures.

Date Published: 25 August 2017
PDF: 8 pages
Proc. SPIE 10346, Plasmonics: Design, Materials, Fabrication, Characterization, and Applications XV, 1034634 (25 August 2017); doi: 10.1117/12.2274748

Published in SPIE Proceedings Vol. 10346:
Plasmonics: Design, Materials, Fabrication, Characterization, and Applications XV
Din Ping Tsai; Takuo Tanaka, Editor(s)