Pulse coding linearization for Brillouin optical time-domain analysis sensors

Area of Science:

• Optoelectronics
• Fiber Optic Sensing
• Signal Processing

Background:

• Brillouin optical time-domain analysis (BOTDA) sensors are crucial for distributed strain and temperature sensing.
• Existing pulse coding techniques in BOTDA suffer from non-linear sensor responses over long distances.
• This non-linearity degrades measurement accuracy and spatial resolution.

Purpose of the Study:

• To introduce a simple logarithmic processing method to enhance BOTDA sensor performance.
• To compensate for the deviation from linearity in BOTDA sensor responses for long code lengths.
• To ensure accurate decoding of probe gain measurements in BOTDA systems.

Main Methods:

• Applying logarithmic processing to the detected probe wave in BOTDA systems.
• Compensating for the non-linear sensor response associated with long pulse code sequences.
• Ensuring the additive property of individual pulse effects for correct gain measurement decoding.

Main Results:

• Experimental demonstration of compensated Brillouin frequency shift error caused by accumulated gain non-linearity.
• Achieved better than 2 MHz precision in an 80 km sensing link within a 200 km fiber loop.
• Demonstrated a spatial resolution of 2 m.

Conclusions:

• The proposed logarithmic processing effectively extends the performance of pulse coding in BOTDA sensors.
• The method successfully mitigates non-linearity issues, enabling high-precision measurements over extended fiber lengths.
• This advancement offers improved capabilities for long-range distributed fiber optic sensing.