Single-Fiber-Based Brillouin Optical Time Domain Analysis With Far-End Modulation

Abstract

The loop configuration consisting of a lead fiber and a sensing fiber is a common approach to realize Brillouin Optical Time-Domain Analysis (BOTDA), which is however impractical to implement for some field scenarios where only a single fiber is physically available. In this paper, a novel single-fiber-based BOTDA with far-end modulation is proposed and experimentally demonstrated, in which an auxiliary light and a pulse are injected from the near-end of the fiber, and the counter-propagating probe light is generated by modulating the auxiliary light from the far-end. By dedicatedly designing the frequency and temporal profile of each lightwave, Brillouin interaction takes place only between the pulse and the probe light, while stray effects such as four wave mixing and Rayleigh beating noise are avoided, which constitutes the key advantage of the propose technique with respect to traditional single-fiber-based BOTDA techniques. A 80-km-long sensing range, 1.73 MHz frequency accuracy and 2 m spatial resolution is experimentally demonstrated with 4000 trace averages.