Multicore optical fiber shape sensors suitable for use under gamma radiation

Area of Science:

• Optoelectronics
• Materials Science
• Radiation Physics

Background:

• Fiber optic sensors are crucial for monitoring in harsh environments.
• High-energy ionizing radiation can degrade optical fiber performance.
• Developing radiation-hardened sensors is essential for applications in nuclear and space industries.

Purpose of the Study:

• To design and implement a fiber optic shape sensor capable of operating in high-energy ionizing environments.
• To investigate the radiation sensitivity of multicore optical fibers.
• To demonstrate the immunity of these sensors to radiation-induced Bragg wavelength shift (RI-BWS).

Main Methods:

• Inscribing fiber Bragg gratings (FBGs) arrays in hydrogen-loaded and unloaded seven-core optical fibers.
• Exposing the FBG arrays to gamma radiation within a metallic circular structure.
• Analyzing the permanent radiation effects and measuring the Bragg wavelength shift and curvature error.

Main Results:

• The hydrogen-loaded fiber exhibited a radiation-induced Bragg wavelength shift (RI-BWS) approximately ten times higher than the unloaded fiber, reaching a maximum of 415 pm.
• Despite significant RI-BWS in the hydrogen-loaded fiber, the use of multicore fibers rendered the shape sensors immune to these shifts.
• Both sensor samples demonstrated a similar curvature error of approximately 1 cm, irrespective of their radiation sensitivity.

Conclusions:

• Multicore optical fibers provide a robust platform for developing radiation-immune fiber optic shape sensors.
• The proposed sensor design is suitable for high-energy ionizing environments, maintaining shape sensing accuracy.
• This technology offers a promising solution for structural health monitoring in demanding applications without requiring fiber modifications.