Compact bending sensor based on a fiber Bragg grating in an abrupt biconical taper

Area of Science:

• Photonics and Optical Sensing
• Fiber Optic Sensors
• Nanofabrication

Background:

• Fiber Bragg gratings (FBGs) are widely used for sensing applications.
• Existing fiber optic bending sensors often lack compactness or require complex fabrication.
• Developing miniaturized, high-performance sensors is crucial for advanced monitoring.

Purpose of the Study:

• To propose and demonstrate a compact bending sensor with a 0.8 mm sensor head.
• To investigate the sensing characteristics of the proposed sensor for curvature measurement.
• To evaluate the temperature cross-sensitivity of the novel sensor design.

Main Methods:

• Fabrication of an abrupt biconical fiber taper using a fusion splicer.
• Inscribing a fiber Bragg grating (FBG) onto the taper using a femtosecond laser.
• Utilizing the cladding-to-core mode coupling in the taper for reflection-mode interferometry.
• Analyzing interference fringe contrast changes for bending detection.

Main Results:

• Successful experimental demonstration of a compact bending sensor.
• The sensor head measures only 0.8 mm in length.
• Bending detection is achieved through changes in interference fringe contrast.
• The sensor exhibits negligible cross-sensitivity to temperature variations.

Conclusions:

• The proposed FBG-based biconical taper sensor offers a compact and effective solution for bending and curvature measurement.
• The sensor's design inherently provides temperature insensitivity.
• This technology holds promise for various applications requiring precise optical sensing.