Sub-millimeter resolution and high-precision φ-OFDR using a complex-domain denoising method

Area of Science:

• Optoelectronics
• Optical Sensing
• Signal Processing

Background:

• Phase noise is a critical limitation in Φ-OFDR, hindering high spatial resolution, precision, and measurement range.
• Existing methods struggle to effectively address phase unwrapping challenges caused by noise and strain accumulation.

Purpose of the Study:

• To develop and validate a novel complex-domain denoising method for effective phase signal unwrapping in Φ-OFDR.
• To improve sensing resolution, precision, and strain measurement capabilities.

Main Methods:

• A complex-domain denoising approach using wavelet packet decomposition on both real and imaginary parts of a constructed complex signal.
• Spatial position correction algorithm to mitigate phase decoherence from strain accumulation.
• Utilization of a high numerical aperture optical fiber to boost Rayleigh scattering intensity.

Main Results:

• Achieved a sensing resolution of 0.89 mm.
• Obtained a root mean square error of 1.5 µε for strain measurement.
• Demonstrated a maximum strain sensing capability of 2050 µε.
• Successfully unwrapped phase signals by denoising real and imaginary components.

Conclusions:

• The proposed complex-domain denoising method effectively addresses phase noise in Φ-OFDR.
• The integrated approach significantly enhances sensing performance, enabling high-resolution and high-precision strain measurements.
• This technique offers a robust solution for overcoming key limitations in Φ-OFDR systems.