Vector Bending Sensor Based on Power-Monitored Tapered Few-Mode Multi-Core Fiber

Area of Science:

• Optoelectronics
• Fiber Optics
• Sensor Technology

Background:

• Fiber optic sensors are crucial for various measurement applications.
• Existing methods may struggle with detecting small curvatures or vector direction.
• Few-mode multi-core fibers (FM-MCF) offer unique light propagation properties.

Purpose of the Study:

• To propose and demonstrate a vector bending sensor based on a tapered FM-MCF.
• To achieve high-sensitivity and directional bending measurements.
• To enable detection of small curvatures with high accuracy.

Main Methods:

• Fabrication of a tapered seven-core six-mode fiber.
• Utilizing power coupling between cores upon bending.
• Employing a power differential method for curvature and direction reconstruction.
• Applying a deep fully connected feedforward neural network (DNN) for demodulation and prediction.

Main Results:

• Sensitivity of not less than 0.14/m^-1 within a curvature range of 2.5 m^-1 to 10 m^-1.
• Mean absolute errors for bending radius and rotation angle prediction below 0.038 m and 3.087°, respectively.
• Successful reconstruction of bending direction and curvature.

Conclusions:

• The tapered FM-MCF vector bending sensor provides a low-cost, high-sensitivity solution.
• The method effectively addresses challenges in detecting small curvatures.
• This technology offers a promising approach for precise bending measurement applications.