High Sensitivity Cryogenic Temperature Sensors Based on Arc-Induced Long-Period Fiber Gratings

Area of Science:

• Optical Fiber Technology
• Materials Science
• Condensed Matter Physics

Background:

• Long-period fiber gratings (LPFGs) are crucial optical components.
• Understanding their temperature-dependent behavior is vital for sensor and communication applications.
• Previous research focused on room-temperature performance, with limited data at cryogenic temperatures.

Purpose of the Study:

• To investigate the temperature evolution of LPFG dispersion curves from room temperature down to 0 K.
• To analyze the impact of temperature on gratings in different fiber types (SMF28, B/Ge co-doped).
• To identify optimal grating parameters for cryogenic temperature sensing.

Main Methods:

• Computer simulations based on previously published experimental data.
• Analysis of dispersion curves for LPFGs in SMF28 and B/Ge co-doped fibers.
• Evaluation of temperature sensitivity near dispersion turning points (DTP).

Main Results:

• Lowest-order cladding modes exhibit the most significant temperature-induced dispersion changes.
• Changes are minimal for cladding modes with DTP in telecommunication windows.
• B/Ge co-doped fibers show higher temperature sensitivity near DTP.
• Optimal grating periods can be determined at room temperature.
• High temperature sensitivities of -850 pm/K (100-200 K) and -170 pm/K (20 K) were predicted.

Conclusions:

• LPFG performance is significantly influenced by temperature, especially at cryogenic levels.
• B/Ge co-doped fibers offer enhanced temperature sensitivity for cryogenic applications.
• The findings enable the design of LPFGs for precise temperature monitoring in extreme environments.