Cladding softened fiber for sensitivity enhancement of distributed acoustic sensing

Area of Science:

• Optical Fiber Sensing
• Materials Science

Background:

• Standard single-mode fiber (SSMF) is widely used in distributed acoustic sensing (DAS).
• Enhancing phase sensitivity in sensing fibers is crucial for improving DAS performance.

Purpose of the Study:

• To propose and demonstrate a novel method for enhancing DAS phase sensitivity.
• To investigate the effect of softening sensing fiber cladding on phase sensitivity.

Main Methods:

• Theoretical analysis of cladding softening's impact on phase sensitivity.
• Fabrication of cladding softened fibers (CSFs) with varying phosphorus-doping concentrations.
• Experimental testing of CSF phase sensitivities.

Main Results:

• Cladding softened fibers demonstrated significantly higher phase sensitivity compared to SSMF.
• A CSF with 0.48 WT% phosphorus doping and 80 µm cladding diameter showed a 54% increase in phase sensitivity over SSMF.
• Phase sensitivity enhancement showed a linear relationship with cladding phosphorus-doping concentration and reduced Young's modulus.

Conclusions:

• Softening the sensing fiber cladding is an effective strategy to enhance DAS phase sensitivity.
• The developed CSF offers improved elasto-optical effects, making it a superior sensing element for DAS and other optical fiber sensing systems.
• This work paves the way for next-generation optical fiber sensing technologies.