Low temperature cross-sensitivity vector torsion sensor based on an in-fiber Mach-Zehnder interferometer with helical...

Area of Science:

• Optical Fiber Sensors
• Interferometry
• Metamaterials

Background:

• Accurate vector torsion measurement is crucial for structural health monitoring and engineering applications.
• Existing fiber optic torsion sensors often face challenges with sensitivity, crosstalk, and directionality.
• Mach-Zehnder interferometers (MZIs) offer a versatile platform for developing novel sensing modalities.

Purpose of the Study:

• To propose and experimentally validate a novel in-fiber vector torsion sensor.
• To leverage helical side-hole fibers (HSHFs) to create a Mach-Zehnder interferometer (MZI) for torsion sensing.
• To investigate the sensor's sensitivity, linearity, and crosstalk characteristics.

Main Methods:

• Fabrication of a Mach-Zehnder interferometer (MZI) by splicing a segment of helical side-hole fiber (HSHF) between two single-mode fibers.
• Excitation of LP01 and LP11 modes within the HSHF to generate intermodal interference.
• Theoretical modeling and experimental measurement of interference pattern shifts and wavelength shifts under applied torsion.

Main Results:

• The proposed HSHF-MZI sensor demonstrated a linear wavelength shift response to torsion with a sensitivity of 0.282 nm/(rad/m).
• Intensity response showed a periodic variation with torsion, yielding a sensitivity of 2.13 dB/(rad/m).
• The sensor exhibited minimal crosstalk to temperature and axial strain, and could detect torsion direction.

Conclusions:

• The helical side-hole fiber Mach-Zehnder interferometer (HSHF-MZI) is a highly sensitive and robust sensor for vector torsion measurement.
• The sensor's design simplifies processing, preserves fiber strength, and offers a wide measurement range.
• This technology holds significant promise for advanced structural health monitoring and precision engineering measurements.