High sensitivity twist sensor based on suspended core fiber Sagnac interferometer with temperature calibration.

Area of Science:

• Optoelectronics
• Fiber Optics Sensors
• Interferometry

Background:

• Optical fiber sensors offer remote and real-time monitoring capabilities.
• Existing twist sensors often lack high sensitivity or temperature calibration.
• Suspend Core Fiber (SCF) provides unique structural properties for sensor development.

Purpose of the Study:

• To propose and demonstrate a high-sensitivity optical fiber twist sensor.
• To enhance twist sensitivity by modifying the SCF.
• To enable simultaneous twist measurement and temperature calibration.

Main Methods:

• Fabrication of a Sagnac interference structure using SCF.
• Filling the SCF air hole with alcohol to enhance sensitivity.
• Utilizing combined intensity and wavelength demodulation for expanded measurement range.
• Employing Mach-Zehnder Interferometer (MZI) fringes for temperature calibration.

Main Results:

• Achieved a high twist sensitivity of 8.37 nm/° by filling SCF with alcohol.
• Demonstrated an expanded valid angle measurement range through dual demodulation techniques.
• Successfully implemented temperature calibration using MZI interference fringes.
• The sensor exhibited low temperature cross-sensitivity.

Conclusions:

• The proposed SCFSI twist sensor offers high sensitivity and temperature calibration capabilities.
• The sensor's compact structure and ease of fabrication make it suitable for practical applications.
• Potential applications include structural health monitoring of buildings, bridges, and other infrastructure.