Asymmetric-core long-period fiber grating for high-sensitivity vector bending sensing

Area of Science:

• Photonics
• Fiber Optic Sensors
• Materials Science

Background:

• Fiber optic sensors commonly face directional ambiguity, limiting their application in vector bending detection.
• Existing fiber sensing technologies often require complex configurations or external components to resolve directional information.

Purpose of the Study:

• To develop a novel fiber optic sensor capable of unambiguous vector bending measurement.
• To address the challenge of directional ambiguity in fiber sensing through intrinsic structural modification.

Main Methods:

• Fabrication of an asymmetric-core long-period fiber grating with a periodic, sinusoidal core deformation.
• Experimental characterization of the sensor's response to bending along different axes.

Main Results:

• The asymmetric-core fiber grating exhibited a highly anisotropic response to bending.
• Demonstrated distinct sensitivities of -50.56 nm/m⁻¹ at 0°, +99.55 nm/m⁻¹ at 180°, and 0.9 nm/m⁻¹ along the orthogonal axis.
• Successfully resolved directional bending information without external components.

Conclusions:

• The proposed sensor offers a simple yet effective solution for vector bending sensing.
• Direct engineering of fiber core geometry presents a promising paradigm for advanced functional photonic devices.