BIREFRINGENT MICRO-STRUCTURED OPTICAL FIBER FOR SENSOR APPLICATION

摘要

The invention relates to the field of fiber structures, preferably adapted for use with fiber Bragg gratings in sensors. The fiber structure comprises a core and a cladding surrounding the core, a central micro structure (1) comprising a first plurality of longitudinal holes, wherein the central microstructure (1) is adapted for guiding optical radiation and for birefringence in the core, a side microstructure (2) comprising a second plurality of longitudinal holes, wherein the side microstructure (2) is at least partly surrounding the central microstructure (1) and is adapted for providing a predetermined mechanical anisotropy (anisotropic response to mechanical strain, or as anisotropic mechanical stiffness), a pressure responsive unit adapted for converting an isotropic pressure force to birefringence changes on the core, a lateral force responsive unit adapted for converting a directional pressure force to birefringence changes on the core, a temperature responsive unit adapted for converting temperature to birefringence changes on the core, and a birefringence responsive unit adapted for converting birefringence in the core to wavelength information. In this way, a fiber structure is provided that allows increasing the ratio of mechanical to thermal sensitivity up to several orders of magnitude with similar sized mode areas.