Directional Torsion Sensor Based on a Two-Core Fiber with a Helical Structure

Area of Science:

• Optoelectronics
• Fiber Optics
• Sensor Technology

Background:

• Torsion measurement is crucial in various engineering applications.
• Existing torsion sensors often lack the ability to determine torsion direction or are complex.
• Fiber-optic sensors offer advantages in harsh environments and remote sensing.

Purpose of the Study:

• To propose and experimentally demonstrate a fiber-optic torsion sensor capable of simultaneously measuring torsion angle and direction.
• To investigate the performance of the sensor with varying pre-twist angles.
• To evaluate the sensor's sensitivity and potential applications.

Main Methods:

• A Mach-Zehnder interferometer (MZI) was constructed using a helical two-core fiber (HTCF) segment and two single-mode fibers (SMFs).
• The helical structure was created by pre-twisting a 1 cm long two-core fiber (TCF).
• Sensor performance was analyzed for pre-twisted angles of 180°, 360°, and 540°.

Main Results:

• The developed sensor successfully measured torsion angle and distinguished torsion direction.
• Maximum sensitivity was observed at a pre-twist angle of 180 degrees.
• Wavelength sensitivities for torsion and temperature were 0.242 nm/(rad/m) and 32 pm/°C, respectively.

Conclusions:

• The fiber-optic torsion sensor based on HTCF offers simultaneous angle and direction measurement.
• The sensor exhibits advantages such as easy fabrication, low cost, compact structure, and high sensitivity.
• This technology holds promise for applications requiring precise torsion monitoring.