Temperature-independent humidity sensor based on FBGs in dual-core optical fiber

A temperature-independent humidity fiber Bragg gratings (FBGs) sensor based on graphene oxide film in dual-core fiber (DCF) has been demonstrated. FBGs are written by using the Ultraviolet (UV) exposure fabrication method through a phase mask on each core of a DCF, which was spliced to a standard single mode fiber (SMF) and tapered the splicing point. The cladding of the DCF was partially abraded so that one of the FBGs could be sensitive to changes in ambient humidity through the GO film. Another FBG is used as a reference to remove the effect of temperature crosstalk. The humidity sensitivity of ~5.582pm/RH% in the range of 45%-85%RH was obtained experimentally. This DCF FBGs sensor has a promising application in the field of temperature-independent parameter measurement.