Abstract

A high-temperature sensor based on a Mach–Zehnder interferometer (MZI) in a conventional single-mode optical fiber is proposed and fabricated by concatenating two microcavities separated by a middle section. A femtosecond laser is used to fabricate a microhole on the center of a fiber end. Then a micro-air-cavity is formed by splicing the microholed fiber end with a normal fiber end. The interferometer is applied for high-temperature sensing, in the range of $500–1200°\mathrm{C}$, with a sensitivity of $109\mathrm{pm}/°\mathrm{C}$ that, to the best of our knowledge, is highest in silica fiber temperature sensors. Also, the interferometer is insensitive to external refractive index (RI), which is desirable for temperature sensors.

© 2011 Optical Society of America

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