Noise resilient quasi-distributed sensing with an interferometric-noise-suppressing Golay coded optical source

Area of Science:

• Photonics
• Optical Sensing
• Signal Processing

Background:

• Quasi-distributed sensor arrays using ultra-weak fiber Bragg gratings (UWFBGs) face challenges with noise and multiplexing density.
• Conventional demodulation techniques struggle with closely-multiplexed UWFBG arrays, limiting performance.
• Existing methods often involve a trade-off between demodulation accuracy and acquisition speed.

Purpose of the Study:

• To propose and demonstrate a noise-resilient demodulation technique for UWFBG-based quasi-distributed sensor arrays.
• To improve signal-to-noise ratio (SNR) and time efficiency in sensing systems with closely-multiplexed sensors.
• To overcome limitations of conventional Golay coding in specific UWFBG array configurations.

Main Methods:

• Development of an interferometric-noise-suppressing (INS-) Golay coded optical pulse source.
• Integration with a medium coherence light source for noise reduction in closely-multiplexed UWFBG arrays.
• Demonstration using 32-bit INS-Golay coded pulse trains for wavelength demodulation.

Main Results:

• Achieved a 5.6-dB signal-to-noise ratio improvement compared to uncoded pulse trains.
• Demonstrated performance comparable to 32-time averaging but with approximately 1/8 the time consumption.
• Exhibited high linearity (up to 0.9986) in temperature sensing with a wavelength demodulation error of ±5 pm.

Conclusions:

• The INS-Golay coding method offers a time-efficient solution for noise reduction in UWFBG sensing systems.
• It effectively alleviates the trade-off between demodulation accuracy and speed for densely multiplexed sensors.
• The technique provides a practical advancement for quasi-distributed fiber optic sensing applications.