Distributed fiber-optic vibration sensing based on phase extraction from time-gated digital OFDR

Area of Science:

• Photonics and Sensing Technologies
• Optical Engineering
• Distributed Sensing Systems

Background:

• Distributed fiber optic sensing offers non-intrusive monitoring capabilities.
• Traditional optical frequency domain reflectometry (OFDR) methods face limitations in quantitative vibration measurement range and reliability due to environmental phase disturbances.
• Accurate and long-range vibration detection is crucial for infrastructure monitoring and security applications.

Purpose of the Study:

• To propose and demonstrate a novel distributed fiber vibration sensing technique based on time-gated digital optical frequency domain reflectometry (TGD-OFDR).
• To achieve quantitative vibration measurement with high spatial resolution and an extended measurement range.
• To enhance the reliability of phase extraction in OFDR-based systems for robust vibration sensing.

Main Methods:

• Development of a TGD-OFDR system incorporating a 90-degree optical hybrid for precise phase extraction.
• Implementation of an increased frequency sweeping speed to significantly mitigate environmental phase disturbance effects.
• Demonstration of the technique using a standard optical fiber to validate performance metrics.

Main Results:

• The proposed TGD-OFDR technique successfully demonstrated a distributed vibration sensor with a measurement range of 40 km.
• Achieved a high spatial resolution of 3.5 meters for pinpointing vibration locations.
• Validated measurable vibration frequencies up to 600 Hz and a minimal measurable vibration acceleration of 0.08g.
• Showcased significantly improved phase extraction reliability compared to conventional OFDR methods.

Conclusions:

• The novel TGD-OFDR technique provides a reliable and effective solution for long-distance quantitative distributed fiber vibration sensing.
• The enhanced phase extraction method overcomes limitations of traditional OFDR, enabling robust performance in challenging environments.
• This technology holds significant potential for applications requiring precise, long-range vibration monitoring.