Open AccessEnhanced subwavelength coupling and nano-focusing with optical fiber-plasmonic hybrid probe
Author(s) -
Khant Minn,
Ho Wai Howard Lee,
Zhenrong Zhang
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.038098
Subject(s) - optics , plasmon , surface plasmon polariton , nanophotonics , materials science , near field scanning optical microscope , surface plasmon , polarization (electrochemistry) , photonic crystal fiber , optical fiber , raman scattering , localized surface plasmon , optoelectronics , raman spectroscopy , physics , optical microscope , scanning electron microscope , chemistry
Metallic nanowires supporting surface plasmon polaritons can localize optical fields at nanoscale tapered ends for near-field imaging. Radially polarized light through the optical fiber or free space efficiently excites the converging radial plasmons at the apex of a sharp tip. However, such radial vector mode excitation through optical fiber requires precise polarization control and strongly polarization maintaining state in optical fiber, thus inducing a complexity for optical applications. In this paper, we propose a photonic-plasmonic probe that uses the linearly polarized source to excite the nanoscale plasmonic hotspot. The linearly polarized fiber mode is converted to radial surface plasmon polaritons (SPPs) through asymmetric coupling at the base of the metallic nano-tip. The radial SPP's then propagate along the half ellipsoid tip and are focused at the tip apex giving rise to the nanoscale concentration of optical energy. The probe can be implemented with near-field imaging techniques such as tip-enhanced Raman microscopy to obtain topographic and chemical spectroscopic information in atomic resolution for studying light-matter interaction at the nanoscale.