High Temperature Measurement Up to 1100 C Using a Polarization-Maintaining

Abstract: A reflective fiber-optic interferometer for ultra-high temperature measurement isproposed and experimentally demonstrated. The device consists of a short piece ofpolarization-maintaining photonic crystal fiber (PM-PCF) spliced with a lead-in single modefiber (SMF) without any offset. The hollow holes within the PM-PCF are partly collapsed dueto the directional arc-heating splicing and excite two linearly polarized (LP) modes over thedownstream PM-PCF. These two LP-modes are reflected at the end face of PM-PCF andbackward recoupled into the lead-in SMF through the collapsed region. A superimposedinterference pattern is obtained as the result of interference of the polarized modes. Theproposed interferometer is demonstrated for ultra-high temperature measurement up to1100 C with a sensitivity of 12.3 pm= C over repeated measurements. Meanwhile, iso-chronally thermal annealing has been studied to address the effect of residual stress in thesensing probe and the feasibility of further improving temperature measurement range of thedevice.Index Terms: Fiber-optic sensor, photonic crystal fiber, interferometer, temperaturemeasurement.