Fiber-optic Fabry-Perot sensor based on spectral quality-enhanced microsphere lens for high-temperature strain...

Area of Science:

• Optoelectronics
• Materials Science
• Sensor Technology

Background:

• High-temperature strain sensing faces limitations in measurement range and accuracy.
• Spectral degradation in sensors at high temperatures restricts performance.
• Existing methods struggle with simultaneous strain and temperature measurement in extreme environments.

Purpose of the Study:

• To develop a fiber-optic Fabry-Perot sensor with enhanced range and accuracy for high-temperature strain sensing.
• To enable simultaneous measurement of strain and temperature.
• To improve sensor stability and reliability in extreme environments.

Main Methods:

• A fiber-optic Fabry-Perot sensor combining an external-cavity Fabry-Perot interferometer (EFPI) with a microsphere lens and a gold-coated fiber Bragg grating (GFBG).
• Utilizing a microsphere lens for optical focusing to maintain EFPI spectral quality.
• Employing a GFBG for precise temperature compensation.
• Implementing a split-type bonding process for enhanced sensor reliability.

Main Results:

• The microsphere lens maintained fringe contrast above 8 dB at 800 μm cavity length, mitigating range limitations.
• The sensor achieved simultaneous strain and temperature measurement up to 800 ℃.
• Mechanical strain exceeding 4000 με was measured with a post-compensation error below 2.17% F.S.
• The sensor demonstrated high precision and stability.

Conclusions:

• The proposed fiber-optic sensor effectively overcomes range and accuracy limitations in high-temperature strain sensing.
• The integrated microsphere lens and GFBG enable robust simultaneous strain and temperature monitoring.
• The sensor is highly suitable for structural health monitoring applications in extreme environments.