Systematic-error suppression in low-coherence Brillouin optical correlation-domain reflectometry

Abstract

Brillouin optical correlation-domain analysis (BOCDA) utilizing low-coherence light sources offers high-resolution distributed strain and temperature sensing. However, conventional BOCDA requires dual-end injection of pump and probe light into the sensing fiber. To overcome this limitation, low-coherence Brillouin optical correlation-domain reflectometry (BOCDR) based on spontaneous Brillouin scattering has emerged, enabling single-end light injection. While a pilot demonstration has shown a spatial resolution of 19 cm, a comparison of its measurement accuracy with standard BOCDR systems is yet to be explored. This study presents a distributed measurement with ~ 3 cm spatial resolution and demonstrates that low-coherence BOCDR eliminates systematic errors caused by direct sinusoidal modulation, offering enhanced measurement precision.

Fiber-tip temperature sensing probe based on standard Brillouin optical correlation-domain reflectometry with sinusoidal modulation

“…The measurement range in BOCDR is represented by the distance d m between correlation peaks. In contrast, a LC-BOCDR, [29][30][31] which uses a noisemodulated light source, has been recently developed. This noise modulation ensures that the reference and Brillouinscattered light waves coincide only near the isochronous point, generating a single correlation peak (zeroth-order only).…”

“…A variable delay line in the reference path allows for sweeping this peak, enabling distributed measurement. The spatial resolution in LC-BOCDR is primarily dictated by the coherence length of the light source and is given by 30,31)…”