Progress toward Sapphire Optical Fiber Sensors for High-Temperature Applications


High-temperature measurements are of significant importance in various harsh-environment engineering fields, such as fossil fuel production, and the metallurgical and aviation industries. In recent years, there is a steady trend to shift from conventional electronic sensors to optical fiber sensors for high-temperature applications. In particular, optical fiber sensors are small in size, immune to electromagnetic interference, readily applicable for remote sensing, have high elasticity, and incorporate capabilities for multiplexing and distributed sensing. However, commonly used fused silica optical fiber sensors exhibit severe limitations at ultrahigh temperatures due to significantly degraded optical and mechanical properties at temperatures > 1000 °C. The excellent optical transparency, thermal and chemical stability, mechanical robustness, and high melting temperature (~2040 °C) of single-crystal sapphire fibers (SFs) make them a strong candidate for sensing applications in high-temperature environments. Translation of the sensing schemes from mature silica fiber sensors to SF sensors has undergone tremendous growth and advancements in the past two decades. However, hurdles to the development of a near-term deployable SF sensing system have proven persistent due to the highly multimodal nature of SFs. This article reviews sensing techniques that have been implemented with SFs recently. The aim is to provide a comprehensive summary of past research on SF sensing systems. Perspectives on further research into the challenging yet promising arena are also discussed.


Electrical and Computer Engineering

Research Center/Lab(s)

Intelligent Systems Center


Army Research Laboratory, Grant W911NF-14-2-0034

Keywords and Phrases

Distributed Sensing; Fabry-Perot Interferometers; Fiber Bragg Gratings (FBGs); High-Temperature Applications; Raman Scattering; Rayleigh Scattering; Sapphire Fiber (SF) Sensors

International Standard Serial Number (ISSN)

0018-9456; 1557-9662

Document Type

Article - Journal

Document Version


File Type





© 2020 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

21 Sep 2020