title: Ultrasensitive photonic crystal fiber refractive index sensor.
abstract: We introduce a microfluidic refractive index sensor based on a directional coupler architecture using solid-core photonic crystal fibers. The sensor achieves very high sensitivity by coupling the core mode to a mode in the adjacent fluid-filled waveguide that is beyond modal cutoff, and with strong field overlap. We demonstrate the device through the selective infiltration of a single hole with fluid along a microstructured optical fiber. A detection limit of 4.6x10(-7) refractive index units has been derived from measurements with a sensitivity of 30,100 nm per refractive index unit, which is the highest for a fiber device to date.
authors.affiliation: Centre for Ultrahigh Bandwidth Devices for Optical Systems, School of Physics, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Darran K C
authors.initials: DK
authors.lastname: Wu
authors.forename: Boris T
authors.initials: BT
authors.lastname: Kuhlmey
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Eggleton
mesh_terms: D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D055100:Optical Fibers; D012031:Refractometry / Q000295:instrumentation*; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D014159:Transducers