High quality phase demodulation method for direct detection Φ-OTDR

Area of Science:

• Optical Fiber Sensing
• Signal Processing

Background:

• Direct detection Φ-OTDR systems face challenges with phase demodulation quality.
• Excessive correlation in temporal sensing sequences leads to demodulation failure and reduced phase quality.
• A novel phase polarity flipping phenomenon introduces additional errors.

Purpose of the Study:

• To address phase demodulation failures and polarity flipping in direct detection Φ-OTDR.
• To propose a robust phase demodulation strategy for accurate intrusion detection.
• To enhance the signal-to-noise ratio and overall performance of Φ-OTDR systems.

Main Methods:

• Leveraging information redundancy between Rayleigh back-scattered temporal sequences.
• Optimal demodulation position selection using cross-correlation analysis.
• Multi-position compensation and phase polarity correction strategy.

Main Results:

• Effective suppression of waveform distortion.
• Significant improvement in the signal-to-noise ratio of demodulated phase.
• Enhanced demodulation effect and detection performance demonstrated experimentally.

Conclusions:

• The proposed strategy effectively overcomes phase demodulation limitations in direct detection Φ-OTDR.
• This method improves the accuracy and reliability of intrusion detection.
• The findings may promote wider application of Φ-OTDR technology.