title: Refractive index sensor based on a polymer fiber directional coupler for low index sensing.
abstract: We propose, numerically analyze and experimentally demonstrate a novel refractive index sensor specialized for low index sensing. The device is based on a directional coupler architecture implemented in a single microstructured polymer optical fiber incorporating two waveguides within it: a single-mode core and a satellite waveguide consisting of a hollow high-index ring. This hollow channel is filled with fluid and the refractive index of the fluid is detected through changes to the wavelength at which resonant coupling occurs between the two waveguides. The sensor design was optimized for both higher sensitivity and lower detection limit, with simulations and experiments demonstrating a sensitivity exceeding 1.4 × 10(3) nm per refractive index unit. Simulations indicate a detection limit of ~2 × 10(-6) refractive index units is achievable. We also numerically investigate the performance for refractive index changes localized at the surface of the holes, a case of particular importance for biosensing.
authors.forename: Kwang Jo
authors.initials: KJ
authors.lastname: Lee
authors.forename: Xiaoqi
authors.initials: X
authors.lastname: Liu
authors.forename: Nelly
authors.initials: N
authors.lastname: Vuillemin
authors.forename: Richard
authors.initials: R
authors.lastname: Lwin
authors.forename: Sergio G
authors.initials: SG
authors.lastname: Leon-Saval
authors.forename: Alexander
authors.initials: A
authors.lastname: Argyros
authors.forename: Boris T
authors.initials: BT
authors.lastname: Kuhlmey