Quantitative amplitude measuring φ-OTDR using multiple uncorrelated Rayleigh backscattering realizations.

Area of Science:

• Optical Engineering
• Sensing Technology
• Materials Science

Background:

• Standard phase-sensitive optical time-domain reflectometry (φ-OTDR) struggles with quantitative strain measurements due to non-linear Rayleigh backscatter amplitude.
• Existing methods lack the precision required for accurate strain quantification.

Purpose of the Study:

• To develop a quantitative strain sensing technique using Rayleigh backscattered light in a modified φ-OTDR system.
• To overcome the inherent non-linear strain response limitations of conventional φ-OTDR sensors.

Main Methods:

• A modified φ-OTDR system was developed, incorporating frequency and polarization multiplexing.
• The system recorded 18 uncorrelated Rayleigh backscattering measurements in parallel.
• A computational technique was employed to recover a linear strain response from the multiple measurements.

Main Results:

• The developed sensor demonstrated a linear strain response with total harmonic distortion below -35 dB.
• The system achieved immunity to signal fading.
• A minimum detectable strain of 5 pɛ/√Hz and a bandwidth of 500 kHz were realized.

Conclusions:

• The proposed technique enables accurate quantitative strain sensing by computationally processing multiple Rayleigh backscattering measurements.
• This advancement offers a robust and sensitive solution for strain monitoring applications.