Fiber Bragg Grating Wavelength Drift in Long-Term High Temperature Annealing

Area of Science:

• Materials Science
• Optical Engineering
• Sensor Technology

Background:

• Fiber Bragg gratings (FBGs) are emerging as high-temperature sensors (600-1200 °C), competing with thermocouples.
• FBGs offer advantages like small size, multiplexing, and extreme temperature survivability for industrial processes.
• Long-term FBG functionality is limited by wavelength drift, with no established cause.

Purpose of the Study:

• To review existing literature on FBG wavelength drift at high temperatures.
• To present new experimental results from extended high-temperature testing of FBGs.
• To identify key factors contributing to wavelength drift and propose causative mechanisms.

Main Methods:

• Literature review of high-temperature FBG wavelength drift.
• Experimental testing of FBGs for over 4000 hours within the 900-1000 °C range.
• Analysis of experimental data to identify drift components and propose physical mechanisms.

Main Results:

• Identified major contributing factors to high-temperature wavelength drift in FBGs.
• Collected over 4000 hours of operational data in the 900-1000 °C range.
• Proposed physical mechanisms to explain the observed long-term wavelength drift.

Conclusions:

• Long-term wavelength drift is a critical limitation for high-temperature FBG sensor applications.
• Understanding the proposed mechanisms is essential for improving FBG stability and reliability.
• Further research is needed to validate proposed mechanisms and enhance sensor performance.