Few-mode fiber based distributed curvature sensor through quasi-single-mode Brillouin frequency shift

Area of Science:

• Optoelectronics
• Fiber Optics
• Sensing Technology

Background:

• Distributed fiber optic sensing offers advantages for structural health monitoring.
• Measuring curvature in optical fibers is crucial for various applications.
• Few-mode fibers (FMF) present opportunities for advanced sensing modalities.

Purpose of the Study:

• To propose and demonstrate a few-mode fiber (FMF) based optical-fiber sensor for distributed curvature measurement.
• To develop a sensor compatible with existing single-mode fiber (SMF) infrastructure.
• To investigate the relationship between fiber bending and Brillouin frequency shift (BFS) in FMF.

Main Methods:

• Utilized a fusion taper to splice FMF with SMF, creating a quasi-single-mode (QSM) operation.
• Employed Brillouin optical time-domain analysis (BOTDA) for distributed sensing.
• Theoretically and experimentally analyzed the BFS response to applied curvature in FMF.

Main Results:

• Successfully demonstrated a distributed curvature sensor based on FMF.
• Achieved SMF-components compatibility through central-alignment splicing.
• Calibrated the precise BFS response to curvature along the fiber link.

Conclusions:

• The proposed FMF sensor effectively measures distributed curvature.
• The sensor system integrates seamlessly with conventional BOTDA systems.
• This technology enables precise, distributed curvature monitoring in various fields.