A Novel Distributed Vibration Sensor Based on Fading Noise Reduction in Multi-Mode Fiber

Area of Science:

• Fiber optics sensing
• Optical physics
• Signal processing

Background:

• Distributed vibration sensing relies on analyzing light signals in optical fibers.
• Existing methods can suffer from fading noise and require extensive data processing.
• Multi-mode fiber (MMF) offers unique polarization properties that can be exploited for sensing.

Purpose of the Study:

• To develop a novel distributed vibration sensing system using MMF for improved event location and spectrum analysis.
• To reduce fading noise and enhance the accuracy of vibration detection.
• To enable efficient spectrum analysis of vibration events.

Main Methods:

• Utilizing a polarization-sensitive optical time domain reflectometer (OTDR) with MMF.
• Leveraging vibration-induced polarization and phase diversification of Rayleigh scattering.
• Implementing data averaging and Fast Fourier Transform (FFT) for signal processing.

Main Results:

• Experimental validation at 5.167 and 10.145 km positions along MMF.
• Demonstrated rapid convergence of averaged OTDR traces behind vibration events.
• Successful extraction of vibration spectra and effective diversification of optical polarization and phase.

Conclusions:

• The proposed MMF-based OTDR system effectively locates vibration events by reducing fading noise.
• The method allows for accurate vibration spectrum analysis, improving sensor reliability and reducing false alarms.
• This approach offers a time-efficient alternative to traditional vibration spectrum analysis methods.