Metal-embedded fiber-optic Fabry-Perot sensors

Area of Science:

• Materials Science
• Optical Engineering
• Sensor Technology

Background:

• Fiber-optic sensors offer remote and non-intrusive sensing capabilities.
• Embedding sensors within materials can provide in-situ monitoring of physical parameters.
• Challenges exist in integrating optical fibers with metals due to thermal expansion and processing stresses.

Purpose of the Study:

• To demonstrate the feasibility of embedding fiber-optic Fabry-Perot interferometers (FFPIs) in aluminum for sensing applications.
• To investigate the impact of embedding on the temperature and ultrasonic pressure sensing performance of FFPIs.
• To develop a method to prevent fiber breakage during the metal casting process.

Main Methods:

• Fabrication of aluminum components with embedded FFPIs using graphite molds and air casting.
• Utilization of stainless-steel stress-relief tubes at the fiber-metal interface to mitigate breakage.
• Characterization of the optical phase response of embedded FFPIs to temperature variations.
• Testing the detection capabilities of embedded FFPIs for ultrasonic waves across a frequency range.

Main Results:

• Successful embedding of FFPIs in cast aluminum without fiber breakage.
• Demonstrated a 2.9-fold increase in optical phase sensitivity to temperature for embedded interferometers compared to those in air.
• Achieved detection of ultrasonic waves in the frequency range of 0.1-8 MHz using the embedded sensors.
• Experimental results showed good agreement with theoretical model calculations.

Conclusions:

• Embedding FFPIs in aluminum is a viable technique for creating robust, in-situ sensors.
• The embedded FFPIs exhibit enhanced temperature sensitivity and effective ultrasonic wave detection.
• The use of stress-relief tubes is crucial for successful fiber integration during metal casting.