Hollow-core fiber Fabry-Perot interferometers with reduced sensitivity to temperature

Area of Science:

• Fiber optics
• Interferometry
• Materials science

Background:

• Hollow-core fibers (HCFs) offer unique properties for sensing applications.
• Fabry-Perot interferometers (FPIs) are sensitive optical devices.
• Temperature fluctuations significantly impact FPI performance, especially in HCFs.

Purpose of the Study:

• To demonstrate a significant reduction in the thermal phase sensitivity of HCF-based FPIs.
• To achieve a record low fiber coil phase thermal sensitivity.
• To explore novel methods for mitigating thermal effects in HCF sensors.

Main Methods:

• Winding a low-temperature-sensitive HCF onto a spool made of an ultralow thermal expansion material.
• Utilizing a Fabry-Perot interferometer configuration with HCF.
• Theoretical analysis and simulations to predict thermal sensitivity.

Main Results:

• Achieved a 3× reduction in thermal phase sensitivity.
• Demonstrated a record low room temperature fiber coil phase thermal sensitivity of 0.13 ppm/K.
• Identified that existing thermal sensitivity reduction methods are not applicable to HCFs.

Conclusions:

• The developed method effectively reduces thermal sensitivity in HCF-FPIs.
• Further reduction, including zero or negative thermal sensitivity, is predicted with specific spool materials.
• The findings are critical for advancing HCF-based sensor technologies.