title: High temperature fiber sensor with high sensitivity based on core diameter mismatch.
abstract: We report a simple fiber sensor for measurement of high temperature with high sensitivity. The sensing head is a multimode-single mode-multimode (MM-SM-MM) fiber configuration formed by splicing a section of uncoated single mode fiber (SMF) with two short sections of multimode fibers (MMF) whose core is composed of pure silica. Because of the mode-field mismatch at the splicing points of the SMF with 2 sections of MMFs, as well as index matching between the core of the MMF and the cladding of the SMF, optical power from the lead-in fiber can be partly coupled to the cladding modes of the SMF through the MMF. The cladding modes of the SMF then re-coupled to the lead-out fiber, in the same fashion. Due to the effective index difference between the core and cladding modes, an interference pattern in the transmission spectrum of the proposed device was obtained. The interference pattern was found to shift to the longer wavelength region with respect to temperature variation. The temperature sensor can measure temperature stably up to more than 900 degrees C with sensitivity of 0.088 nm/ degrees C.
authors.affiliation: Department of Information and Communications, School of Photon Science and Technology, Gwangju Institute of Science and Technology, Buk-gu, Gwangju, Korea.
authors.forename: Linh Viet
authors.initials: LV
authors.lastname: Nguyen
authors.forename: Dusun
authors.initials: D
authors.lastname: Hwang
authors.forename: Sucbei
authors.initials: S
authors.lastname: Moon
authors.forename: Dae Seung
authors.initials: DS
authors.lastname: Moon
authors.forename: Youngjoo
authors.initials: Y
authors.lastname: Chung
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D012031:Refractometry / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013696:Temperature; D013817:Thermography / Q000295:instrumentation*; D013821:Thermometers; D014159:Transducers