title: Spatial optical filter sensor based on hollow-core silica tube.
abstract: A spatial optical filter based on a hollow-core silica tube is proposed. Because of the hollow-core dimensions, it is possible to obtain a periodical spatial filter ranging from 1200 to 1700 nm with a channel spacing of 2.64 THz. The bandwidth is approximately 5.32 nm, and the isolation loss is ~30 dB. The optical losses are approximately ~0.67 dB/mm for a wavelength of 1500 nm. The 40 mm long spatial optical filter is tested as a sensing element and subjected to different physical parameters. The spatial optical filter is wavelength sensitive to strain and temperature, while for refractive-index variations there is an optical power dependency. This fiber structure can be used as a sensing element for extreme conditions, such as in very high temperature environments, where it presents a sensitivity of 27.5 pm °C(-1).
authors.affiliation: INESC Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal.
authors.forename: Marta S
authors.initials: MS
authors.lastname: Ferreira
authors.forename: Kay
authors.initials: K
authors.lastname: Schuster
authors.forename: Jens
authors.initials: J
authors.lastname: Kobelke
authors.forename: José L
authors.initials: JL
authors.lastname: Santos
authors.forename: Orlando
authors.initials: O
authors.lastname: Frazão