R&D of optical fiber based sensors and their applications

Two optical sensing technologies that are promising for infrastructure applications are (1) Optical Brillouin Time Domain Analysis /Reflectometry (BOTDA/R) sensors for distributed strain and temperature measurements, and (2) Fiber Bragg Grating (FBG) sensors for localized strain measurements. In this paper, recent advances of these two technologies by the authors' group are introduced for structural health monitoring of infrastructures. This paper is organized into two main parts. The first part presents the latest development of direct optical fiber (OF) based sensors, indirect OF-based sensors, and OF-based smart structures. The second part discusses various case studies of OF-based sensors and smart structures in more than 10 critical infrastructures, including long-span bridges, civil defense structure, pitch road, and protection pipeline of oil drilling wells. Although OF sensors have recently gained increasing acceptances by researchers and engineers, some application-related issues yet to be addressed are pointed out and commented upon.