Directional Torsion Sensor Based on a Paired Helical-Type Multimode Fiber.

Area of Science:

• Optoelectronics
• Fiber Optics
• Sensor Technology

Background:

• Torsion sensing is crucial in various industrial applications.
• Existing torsion sensors often suffer from cross-sensitivity to temperature.
• Developing directional torsion sensors with high accuracy is an ongoing challenge.

Purpose of the Study:

• To demonstrate a novel fiber optic torsion sensor capable of directional discrimination.
• To investigate the performance characteristics of the proposed sensor.
• To evaluate the sensor's susceptibility to temperature variations.

Main Methods:

• Fabrication of a single-mode-twisted multimode-single-mode (STMS) fiber structure.
• Fusion-splicing single-mode fibers (SMFs) with a twisted multimode fiber (MMF) segment.
• Experimental analysis of resonance wavelength shifts under varying twist rates and directions.
• Quantification of wavelength and transmission sensitivities.
• Assessment of temperature crosstalk.

Main Results:

• The STMS fiber sensor successfully discriminated between clockwise and counterclockwise torsion.
• Resonance wavelength shifts correlated with twist direction and magnitude.
• Measured wavelength sensitivity: -1.38 nm/rad·m⁻¹.
• Measured transmission sensitivity: 3.12 dB/rad·m⁻¹.
• Minimal temperature crosstalk of 0.0072 (rad/m)/°C was observed.

Conclusions:

• The developed STMS fiber sensor provides directional torsion measurement capabilities.
• The sensor exhibits high sensitivity and low temperature cross-sensitivity.
• This technology holds promise for accurate torsion monitoring in environments with temperature fluctuations.