Averaging-free vector Brillouin optical time domain analyzer assisted by reference probe lightwave

Area of Science:

• Optoelectronics
• Fiber Optic Sensing
• Photonics

Background:

• Distributed Brillouin optical time domain analysis (BOTDA) is crucial for fiber optic sensing.
• Existing BOTDA systems often require trace averaging, limiting measurement speed and efficiency.
• Simultaneous measurement of Brillouin gain spectrum (BGS) and Brillouin phase-shift spectrum (BPS) is challenging.

Purpose of the Study:

• To propose and demonstrate a vector BOTDA system for simultaneous BGS and BPS measurements.
• To eliminate the need for trace averaging in BOTDA systems.
• To enhance the signal-to-noise ratio (SNR) for improved measurement accuracy.

Main Methods:

• A vector BOTDA system was designed, incorporating a reference light and Stokes probe light.
• A commercial integrated coherent receiver with single sideband (SSB) modulation was utilized.
• Analysis of receiver outputs at specific intermediate frequencies (IF) allowed simultaneous amplitude and phase signal retrieval.

Main Results:

• The system successfully performed simultaneous distributed BGS and BPS measurements without trace averaging.
• Improved SNR was achieved, negating the need for repeated signal acquisitions.
• Experiments over an 18.2 km fiber under test (FUT) demonstrated a spatial resolution of 2 m.

Conclusions:

• The developed vector BOTDA system enables efficient and accurate simultaneous distributed BGS and BPS measurements.
• The proposed scheme offers a significant advancement in fiber optic sensing capabilities.
• The system's performance was validated through experimental demonstration with high spatial resolution.