title: Highly sensitive and simple method for refractive index sensing of liquids in microstructured optical fibers using four-wave mixing.
abstract: We present both experimental measurements and simulations for a simple fiber-optical liquid refractive index sensor, made using only commercially available components and without advanced postprocessing of the fiber. Despite the simplicity, we obtain the highest sensitivity experimentally demonstrated to date for aqueous solutions (refractive index around 1.33), which is relevant for extensions to biosensing. The sensor is based on measuring the spectral shift of peaks arising from four-wave mixing (FWM), when filling the holes of a microstructured fiber with different liquid samples and propagating nanosecond pulses through the silica-core of the fiber. To the best of our knowledge, this is also the first experiment where a liquid is filled into the holes of a solid-core microstructured fiber to control the phase-match conditions for FWM.
authors.affiliation: DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, Ørsteds Plads 343, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Frosz
authors.forename: Alessio
authors.initials: A
authors.lastname: Stefani
authors.forename: Ole
authors.initials: O
authors.lastname: Bang
mesh_terms: D015374:Biosensing Techniques; D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D005336:Fiber Optic Technology; D008422:Materials Testing; D016011:Normal Distribution; D055100:Optical Fibers; D055095:Optics and Photonics; D012031:Refractometry / Q000295:instrumentation* / Q000379:methods; D014159:Transducers; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water