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OFDR-based shape sensor using a plane-by-plane-inscribed weak FBG array in multicore fiber
Optics Express
|August 14, 2026
Summary
A novel Optical Frequency Domain Reflectometry (OFDR) shape sensor uses weak fiber Bragg gratings (WFBGs) in multicore fiber (MCF). This advanced sensor achieves high accuracy in 2D and 3D shape reconstruction.
Area of Science:
- Fiber optic sensing
- Optical instrumentation
- Materials science
Background:
- Fiber Bragg gratings (FBGs) are widely used for sensing applications.
- Multicore fiber (MCF) offers increased sensing capacity and multiplexing capabilities.
- Existing FBG inscription techniques can be complex and time-consuming.
Purpose of the Study:
- To demonstrate an Optical Frequency Domain Reflectometry (OFDR)-based shape sensor.
- To develop a novel method for inscribing weak fiber Bragg gratings (WFBGs) in MCF.
- To achieve accurate 2D and 3D shape sensing using the fabricated WFBG array.
Main Methods:
- Fabrication of a WFBG array in MCF using a femtosecond-laser plane-by-plane technique.
- Introduction of an integrated modulation plane for simultaneous multi-core modulation.
- Optimization of inscription parameters (energy, grating order, modulation planes).
- Interrogation of the WFBG array using OFDR.
Main Results:
- Demonstration of a 60-cm-long WFBG array with 60 gratings.
- Achieved a fabrication speed of 35 seconds per WFBG with 10 modulation planes.
- Reported relative reconstruction errors of 1.41% in 2D and 1.95% in 3D shape sensing.
Conclusions:
- The developed WFBG array in MCF is suitable for high-accuracy shape sensing.
- The femtosecond-laser plane-by-plane technique offers an efficient method for WFBG fabrication.
- The integrated modulation plane simplifies the alignment process for multi-core inscription.
