Large dynamic strain measurement via slope-assisted Brillouin optical time domain reflectometry using a frequency...

Area of Science:

• Optical Engineering
• Sensing Technology
• Fiber Optics

Background:

• Traditional Brillouin optical time domain reflectometry (BOTDR) methods face limitations in dynamic strain measurement range.
• The Brillouin gain spectrum (BGS) bandwidth restricts the measurable strain range in conventional BOTDR.

Purpose of the Study:

• To propose and demonstrate a novel method for measuring large dynamic strain using slope-assisted Brillouin optical time domain reflectometry (SA-BOTDR).
• To enhance the strain measurement range and accuracy in single-mode fibers.

Main Methods:

• Implemented a linear artificial slope using a frequency equalizer as the linear response region.
• Utilized the relationship between Brillouin frequency shift (BFS) and signal intensity for strain measurement.
• Employed a ∼1.94-km single-mode fiber (SMF) for experimental validation.

Main Results:

• Achieved large dynamic strain measurement up to 3108 µε with a spatial resolution of 5 m.
• Established a strong linear relationship between signal strength and strain at vibration frequencies of 10.3 Hz and 13.1 Hz.
• Demonstrated low maximum measured errors of 0.5 Hz@10.3 Hz and 0.8 Hz@13.1 Hz for vibration frequency.

Conclusions:

• The proposed SA-BOTDR method effectively measures large dynamic strain, overcoming the limitations of traditional BGS bandwidth.
• The technique offers a robust and accurate approach for strain monitoring in optical fibers.
• This advancement has significant implications for structural health monitoring and various sensing applications.