A Panda fiber temperature sensor up to 900°C

Abstract

The use of Panda-type polarization-maintaining (PM) fiber for the localized sensing of high temperatures was analyzed with simulations and experiments up to 900°C. Accuracy and repeatability of the results started to decline above 800°C. Fused silica optical fiber melts at 1700°C, which sets an ultimate limit for measurable temperatures. In practice, optical fiber birefringence restricts the maximum temperature to 1060°C where PM fiber loses its ability to maintain polarization. Three sensor fibers (4, 5 and 10 cm long) were spliced at 45° angles to input/output fibers and calibrated in an oven from room temperature to 850–900°C temperature range. Two superluminescent light-emitting diodes (SLEDs) were coupled together as a broadband light source. Birefringence-induced change of the polarization in the sensor fiber was measured with a polarization splitter and an optical spectrum analyzer (OSA) as a function of the wavelength. Temperature-dependent birefringence generates a sinusoidal reflection spectrum from the input polarization mode to the orthogonal output polarization mode. Temperature changes could be concluded from variations in these spectra. Finally, a small fusion device, NORTH, at DTU, Denmark was successfully used as a testbed to make sure that the sensors can handle transportation and the instrumentation required for vacuum operation and still produce sensible data from a harsh environment.

Fiber Optic Temperature Sensor System Using Air-Filled Fabry–Pérot Cavity with Variable Pressure

“…Temperature is a key parameter that needs to be monitored and controlled precisely in a wide range of applications, including industrial, chemical, structural, biomedical, and environmental aspects. For the last three decades, various techniques have been developed regarding fiber optic temperature sensors such as fiber-Bragg grating (FBG)-based sensors [ 5 ], tapered fiber [ 6 ], waveguide coupling devices using surface plasmon resonance [ 7 ], fiber ring laser demodulation [ 8 ], modified fibers (panda fibers [ 9 ], multicore fiber [ 10 ]), and interferometer-based sensors [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. Among these, temperature sensors based on Fabry–Pérot (FP) interferometers have proved to be an attractive option because of their additional advantages of simple structure and easy fabrication.…”

PANDA Fiber Sagnac Interferometer for Temperature Sensor Application

“…However, they are suffered by several limitation when operating in extremely harsh environments with high pressure, high temperatures and strong electromagnetic radiation [6,7]. The demand for developing optical temperature sensors has been drastically increased due to the benefits they offer over conventional technologies, such as compact size, effective in distant sensing, resistant to electromagnetic interference, and multiplexable [8,9].…”