Enhanced hybrid distributed multi-parameter fiber sensing based on distributed Brillouin amplification.

Area of Science:

• Fiber optic sensing
• Distributed sensing systems
• Photonics and optical technologies

Background:

• Distributed multi-parameter fiber sensing requires high signal-to-noise ratio (SNR) for accurate measurements.
• Traditional methods face limitations in SNR, especially over long distances.
• Phase-sensitive optical time-domain reflectometry (φ-OTDR) is a key technique for distributed sensing.

Purpose of the Study:

• To propose and demonstrate an enhanced hybrid distributed multi-parameter fiber sensing system.
• To improve the SNR of Rayleigh backscattering using distributed Brillouin amplification.
• To achieve simultaneous distributed acoustic and temperature sensing.

Main Methods:

• Utilizing a continuous optical chirp chain (OCC) as a Brillouin pump for uniform probe pulse amplification.
• Employing a Brillouin loss scheme to extract temperature information from OCC.
• Implementing a 60 ns segment duration and 250 MHz sweeping range for OCC.
• Conducting experiments over 50 km of single-mode fiber.

Main Results:

• Achieved a 10 dB enhancement in the SNR of φ-OTDR at the fiber end.
• Demonstrated distributed acoustic sensing with a strain sensitivity of 64 pε/Hz^1/2.
• Achieved distributed temperature sensing with a precision of 0.2 ℃.
• Maintained a spatial resolution of 6 m over the 50 km fiber.

Conclusions:

• The proposed enhanced hybrid distributed sensing system significantly improves SNR.
• The system effectively enables simultaneous distributed acoustic and temperature sensing.
• This approach offers a robust solution for long-range, multi-parameter fiber optic sensing.