Our study examines the transmission characteristics of bi-tapered optical fibers, i.e. fibers that have a tapered down and up span with a waist length separating them. The applications to aqueous and vapor phase biomolecular sensing demand high sensitivity. A bi-tapered optical fiber platform is suited for label-free biomolecular detection and can be optimized by modification of the length, diameter and surface properties of the tapered region. We have developed a phase sensitive method based on interference of two or more modes of the fiber and we demonstrate that our fiber sensitivity is of order 10^-4 refractive index units. Higher sensitivity can be achieved, as needed, by enhancing the fiber design characteristics.

Date Published: 9 March 2016
PDF: 10 pages
Proc. SPIE 9719, Biophysics, Biology, and Biophotonics: the Crossroads, 971907 (9 March 2016); doi: 10.1117/12.2208934

Published in SPIE Proceedings Vol. 9719:
Biophysics, Biology, and Biophotonics: the Crossroads
Adam Wax; Vadim Backman, Editor(s)