title: Tapered optical fibers designed for surface plasmon resonance phase matching.
abstract: Combining a modified two-step chemical etch method with equations to predict etch parameters and photon-plasmon phase-matching resulted in single-mode tapered optical fibers (TOFs) to optimize electromagnetic field enhancement. The phase-matching equation was used to identify the angle of incidence near the TOF cutoff radius at which surface plasmon resonance (SPR) is maximized. The axisymmetric Young-Laplace equation was used to predict the angle of incidence from the fabrication of a TOF via chemical etching. An optimal cone angle of 20.0 degrees , angles of incidence averaging (81.6 +/- 1.9) degrees , and tip diameters of (80.0 +/- 14.1) nm were achieved through a two-step etching process. These TOF characteristics maximize SPR excitation and field enhancement. The refractive index for optimized SPR excitation in the fabricated TOFs at a wavelength of 650 nm was found to be 1.343.
authors.affiliation: Department of Chemical Engineering, 3290 MEB, University of Utah, Salt Lake City, Utah 84112, USA.
authors.forename: Yinni
authors.initials: Y
authors.lastname: Yu
authors.forename: Phillip
authors.initials: P
authors.lastname: Blake
authors.forename: D Keith
authors.initials: DK
authors.lastname: Roper
mesh_terms: D055100:Optical Fibers; D020349:Surface Plasmon Resonance