Distributed Brillouin Sensing: Time-Domain Techniques

Abstract

Distributed optical fiber sensors based on spontaneous and stimulated Brillouin scattering have been a subject of intense research and industrial developments for almost 30 years. Combining interrogation methods based on optical time-domain reflectometry and the dependence of Brillouin scattering on environmental variables, such as temperature and strain, high-performance distributed sensing techniques have been developed over the last decades for a wide range of industrial applications. This chapter presents a comprehensive description of the fundamentals of time-domain techniques exploited for distributed Brillouin optical fiber sensing. This includes the basic principles and limitations of different classical configurations. Theoretical descriptions of sophisticated techniques to overcome the fundamental limitations of classical Brillouin time-domain schemes are also presented. In this way, the most-common advanced approaches to reach high spatial resolution, dynamic, and long-range distributed Brillouin sensing are thoroughly described from theoretical and practical points of view. The material presented in this chapter is intended to serve as a guideline to design and implement state-of-the-art distributed Brillouin optical fiber sensors exploiting time-domain interrogation approaches.