U-shape core-offset fiber sensor with submicrostrain resolution over a 35 millistrain range

Area of Science:

• Materials Science
• Optical Engineering
• Structural Health Monitoring

Background:

• Fiber optic sensors are vital for structural monitoring, but traditional sensors have limited strain detection ranges (<1%).
• Existing technologies struggle to meet the demands for high-resolution, large-strain measurement in steel structures.

Purpose of the Study:

• To develop a novel fiber optic sensor for large strain measurement with sub-micro resolution.
• To overcome the limitations of conventional fiber sensors in terms of strain range and accuracy.

Main Methods:

• A U-shape core-offset fiber sensor was designed and fabricated using four fiber segments with slight length differences.
• The sensor utilizes the interference of reflected high-order modes at silica/air interfaces to enable strain detection.
• The hybrid air-glass structure facilitates large transverse bending for compression and tension measurements.

Main Results:

• The proposed sensor achieves a large strain detection range exceeding 35 mɛ.
• High strain sensitivity of 20.75 pm/µɛ and accuracy of 0.5 µɛ were demonstrated.
• Simultaneous measurement of compression and tension strain was successfully achieved.

Conclusions:

• The novel U-shape core-offset fiber sensor offers a significant advancement for large strain measurement.
• The sensor's high sensitivity, large range, and ease of fabrication make it suitable for practical structural monitoring applications.
• This technology addresses the critical need for accurate, wide-range strain sensing in demanding environments.