title: Sensitivity improvement of a humidity sensor based on silica nanospheres on a long-period fiber grating.
abstract: This work addresses a new configuration that improves the sensitivity of a humidity sensor based on a long-period fiber grating coated with a SiO(2)-nanospheres film. An intermediate higher refractive index overlay, deposited through Electrostatic Self-Assembly, is placed between the fiber cladding and the humidity sensitive film in order to increase the total effective refractive index of the coating. With this intermediate design, a three-fold improvement in the sensitivity was obtained. Wavelength shifts up to 15 nm against 5 nm were achieved in a humidity range from 20% to 80%.
authors.affiliation: Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal.
authors.forename: Diana
authors.initials: D
authors.lastname: Viegas
authors.forename: Javier
authors.initials: J
authors.lastname: Goicoechea
authors.forename: José Luís
authors.initials: JL
authors.lastname: Santos
authors.forename: Francisco Moita
authors.initials: FM
authors.lastname: Araújo
authors.forename: Luís Alberto
authors.initials: LA
authors.lastname: Ferreira
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Arregui
authors.forename: Ignacio R
authors.initials: IR
authors.lastname: Matias