Concave-lens-like long-period fiber grating bidirectional high-sensitivity bending sensor

Area of Science:

• Photonics and Optical Sensing
• Fiber Optic Sensors
• Nanotechnology

Background:

• Fiber-optic sensors are crucial for various monitoring applications.
• Conventional long-period fiber gratings (LPFGs) have limitations in sensitivity.
• Developing high-sensitivity sensors is essential for precise measurements.

Purpose of the Study:

• To design and demonstrate a novel bidirectional high-sensitivity fiber-optic bending sensor.
• To utilize a concave-lens-like LPFG (CLL-LPFG) structure for enhanced performance.
• To investigate the bending sensitivity and potential improvements of the proposed sensor.

Main Methods:

• Fabrication of a CLL-LPFG with arc-shaped grating planes.
• Analysis of the interaction between eigencladding modes and the device surface.
• Experimental measurement of bending sensitivity within a specific range.

Main Results:

• The CLL-LPFG exhibits significantly enhanced sensitivity to bending.
• Achieved bending sensitivity of -32.782 nm/m^-1 within the 0-2.08 m^-1 range.
• Sensitivity is approximately sixfold higher than conventional counterparts.

Conclusions:

• The CLL-LPFG is a promising structure for high-sensitivity bidirectional fiber-optic bending sensing.
• Sensitivity can be further improved by optimizing grating parameters.
• Temperature characteristics offer a means to manipulate the grating spectrum.