Optical Fiber Temperature and Torsion Sensor Based on Lyot-Sagnac Interferometer

Area of Science:

• Photonics
• Fiber Optics Sensing
• Interferometry

Background:

• Traditional sensors often struggle with simultaneous measurement of multiple physical parameters.
• Lyot-Sagnac interferometers offer potential for novel sensing applications.
• High-birefringence (HiBi) fiber is sensitive to external perturbations.

Purpose of the Study:

• To propose and demonstrate an optical fiber sensor for simultaneous temperature and torsion measurement.
• To enhance the sensitivity of temperature sensing compared to single Sagnac interferometers.
• To establish a reliable method for torsion angle detection using spectral changes.

Main Methods:

• Implementation of a Lyot-Sagnac interferometer incorporating two sections of HiBi fiber.
• One HiBi fiber section designated as the temperature-sensitive region, the other as a reference.
• Experimental validation of the sensor's response to temperature variations and fiber twisting.

Main Results:

• The sensor exhibits a temperature sensitivity of -17.99 nm/°C, over 12 times greater than single Sagnac interferometers.
• Temperature changes cause a measurable shift in the output spectrum's envelope.
• Fiber torsion directly influences fringe visibility, following a sine relationship with the twist angle up to 360°.

Conclusions:

• The proposed Lyot-Sagnac interferometer effectively enables simultaneous measurement of temperature and torsion.
• The distinct responses of spectral envelope shift and fringe visibility allow for independent parameter determination.
• This sensor design presents a significant advancement in multi-parameter optical fiber sensing.