Low harmonic distortion demodulation scheme for PMDI-TDM structure fiber-optic sensor array

Area of Science:

• Optical Engineering
• Sensor Technology
• Signal Processing

Background:

• Path-matched differential interferometry (PMDI) with time-division multiplexing (TDM) is a sensitive fiber-optic sensor technique.
• Traditional 3x3 optical fiber coupler demodulation in PMDI-TDM systems suffers from harmonic distortion due to non-ideal coupler characteristics and photodetector inconsistencies.
• This distortion limits the accuracy and applicability of PMDI-TDM sensor arrays.

Purpose of the Study:

• To propose and validate a low harmonic distortion signal demodulation scheme for PMDI-TDM fiber-optic sensor arrays.
• To address the limitations of existing demodulation methods caused by non-ideal optical components and detectors.
• To enhance the performance of large-scale multiplexed fiber-optic sensing systems.

Main Methods:

• Development of a novel demodulation scheme based on multi-channel parameter fitting and tracking.
• Utilizing the Random Sample Consensus (RANSAC) algorithm for accurate ellipse parameter extraction from interference fringes.
• Employing a Multi-channel Parallel Extended Kalman Filter (MPEKF) for real-time tracking of demodulation parameters.

Main Results:

• The proposed RANSAC-MPEKF scheme effectively suppresses harmonic distortion in PMDI-TDM sensor arrays.
• Demonstrated ability to mitigate the impact of outliers and non-ideal system components (3x3 coupler, photodetectors).
• Achieved a high demodulation rate of ≥500 kHz with a Total Harmonic Distortion (THD) value better than 0.12%.
• Minimal resource consumption, suitable for large-scale multiplexing.

Conclusions:

• The RANSAC-MPEKF scheme provides a robust solution for low-harmonic-distortion signal demodulation in PMDI-TDM fiber-optic sensor arrays.
• The method significantly improves demodulation accuracy and reliability, overcoming limitations of previous techniques.
• This advancement is crucial for the practical implementation of high-performance, large-scale fiber-optic sensing applications.