Single-shot chirped pulse BOTDA for static and dynamic strain sensing

Area of Science:

• Optics and Photonics
• Materials Science
• Sensor Technology

Background:

• Distributed high-frequency dynamic strain sensing is crucial for structural health monitoring.
• Ultra-fast Brillouin optical time-domain analysis (BOTDA) is a key technique for such applications.
• Existing BOTDA methods can be time-consuming due to frequency sweeping.

Purpose of the Study:

• To propose and demonstrate a novel method for ultra-fast BOTDA using a chirped pulse.
• To enable static and dynamic strain measurement without frequency sweeping.
• To achieve high acquisition rates and immunity to polarization fading.

Main Methods:

• Utilizing a chirped pulse as a pump signal in BOTDA.
• Extracting relative Brillouin frequency shift (BFS) changes via real-time delays between adjacent Brillouin traces.
• Employing single-shot measurement and electrical delay time measurement.

Main Results:

• Demonstrated BFS measurement resolution of 0.42 MHz.
• Achieved a spatial resolution of 4.5 m over a 5 km non-uniform fiber.
• System exhibits a high acquisition rate, limited only by sensor length, and is immune to polarization fading.

Conclusions:

• The proposed chirped pulse BOTDA method offers an efficient solution for ultra-fast dynamic strain sensing.
• The technique eliminates the need for time-consuming frequency sweeping, enhancing measurement speed.
• The system demonstrates robust performance with high resolution and immunity to common sensing issues.