Absolute sapphire optical fiber sensor for high-temperature applications

This paper describes sapphire fiber-based EFPI sensors incorporated with wavelength scanning absolute signal demodulation Silica-based optical fiber extrinsic Fabry-Perot interferometric (EFPI) sensors have been very successfully used in measuring a wide range of physical and chemical parameters. However, these fibers can only sustain temperatures of 800 degrees C because of germanium thermal diffusion affecting both the attenuation and waveguide multi-mode properties of die fiber. Since sapphire has a melting point above 2000 degrees C, sapphire optical fiber can be potentially used up to 2000 degrees C in an EFPI scheme. We obtain a resolution of 0.02 pm with a dynamic range of 27 mu m for micro-displacement measurement.