Fiber Bragg grating regeneration at 450°C for improved high temperature sensing

Area of Science:

• Materials Science
• Optical Engineering
• Fiber Optics

Background:

• Fiber Bragg gratings (FBGs) are crucial optical components.
• Regenerating FBGs at lower temperatures is desirable for energy efficiency and preserving fiber properties.
• Understanding regeneration mechanisms is key to optimizing FBG performance.

Purpose of the Study:

• To achieve efficient regeneration of Type-I FBGs at a record-low temperature.
• To investigate the impact of regeneration temperature on mechanical strength and high-temperature sensing capabilities.
• To explore the mechanisms governing FBG regeneration dynamics.

Main Methods:

• Photo-inscription of Type-I FBGs in hydrogen-loaded B/Ge co-doped silica single-mode optical fibers.
• Annealing experiments at various temperatures, including a novel low-temperature approach (450°C).
• Mechanical strength testing and high-temperature (up to 900°C) sensing performance evaluation of regenerated gratings.

Main Results:

• Efficient FBG regeneration achieved at 450°C, the lowest reported temperature.
• Preserved mechanical strength of the annealed fiber.
• Regenerated gratings demonstrated reliable temperature sensing up to 900°C.
• Higher annealing temperatures (above 600°C) led to faster regeneration of strong gratings.

Conclusions:

• Low-temperature regeneration of FBGs is feasible, preserving critical fiber properties.
• The study highlights a new pathway for robust, high-temperature sensing FBGs.
• Regeneration dynamics are temperature-dependent, suggesting a complex interplay of different physical mechanisms.