title: Low-cost high-performance fiber-optic pH sensor based on thin-core fiber modal interferometer.
abstract: A new fiber-optic pH sensor based on a thin-core fiber modal interferometer with electrostatic self-assembled nanocoating is presented. After inserting a segment of thin-core fiber into a standard single-mode fiber, high-order cladding modes are excited and interfere with the core mode to form an in-fiber modal interferometer. The side surface of the sensor is then deposited with poly(allylamine hydrochloride) and poly(acrylic acid) nanocoating by electrostatic self-assembly technique. A fast and linear response is obtained in either acid or alkali solution (in the pH range 2.5 to 10) with resolution of 0.013 pH unit.
authors.affiliation: Center for Optical and Electromagnetic Research, State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310058, China.
authors.forename: Bobo
authors.initials: B
authors.lastname: Gu
authors.forename: Ming-Jie
authors.initials: MJ
authors.lastname: Yin
authors.forename: A Ping
authors.initials: AP
authors.lastname: Zhang
authors.forename: Jin-Wen
authors.initials: JW
authors.lastname: Qian
authors.forename: Sailing
authors.initials: S
authors.lastname: He
mesh_terms: D002681:China; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000191:economics / Q000295:instrumentation*; D006863:Hydrogen-Ion Concentration; D007368:Interferometry / Q000295:instrumentation*; D012031:Refractometry / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers