title: High-sensitivity fiber-loop ringdown evanescent-field index sensors using single-mode fiber.
abstract: We combine the evanescent-field scattering sensing mechanism with the fiber-loop ringdown detection scheme to create a new type of fiber optic index sensor using partially cladded single-mode fiber as a sensing element. A detection limit for an optical index change of 3.2x10(-5) is demonstrated in the initial examination by using certified refractive index oils and laboratory-made sodium chloride solutions. This is the highest sensitivity for a fiber optic index sensor to date (to our knowledge) without using any chemical coating, delicate fiber components, and/or sophisticated architecture at the sensor head. A potential detection limit can be of the order of 10(-6).
authors.affiliation: Department of Physics and Astronomy, Institute of Clean Energy Technology, Mississippi State UniversityStarkville, Mississippi 39759, USA. cw175@msstate.edu
authors.forename: Chuji
authors.initials: C
authors.lastname: Wang
authors.forename: Chamini
authors.initials: C
authors.lastname: Herath