Super-speed high-resolution distributed Brillouin sensor for mapping strain waves propagating an optical fiber

Abstract

Distributed fiber sensors based on Brillouin scattering have recently advanced into high-speed and high-resolution systems, aimed at identifying and characterizing dynamic strain events in civil structures and materials. This article introduces a super-speed, high-resolution distributed Brillouin sensor implemented through the utilization of lock-in-free balanced detection of orthogonally-polarized probe sidebands. The proposed system achieves a sampling rate exceeding 106 Sa/s (1 MSa/s) with a centimeter-level spatial resolution, surpassing the capabilities of previous Brillouin sensors. In test experiments, we demonstrate the polarization-independent measurement of the local Brillouin gain spectrum at a sampling rate of 2 MSa/s with a spatial resolution of 5 cm. Additionally, we acquire the full distribution map of Brillouin frequency along a 5.2 m standard single-mode fiber, utilizing a 10 kHz repetition rate and 144 sampling points. This high-performance system allows us to analyze the occurrence and propagation of the axial strain waves in a suspended optical fiber, induced by the popping noise of a powered speaker.