Fiber-Optic Sensing Systems: Fiber-Bragg Grating Sensor and Swept Laser Interrogation Platform

Abstract

• Introduction to Fiber-Optic Sensing • Focus on Fiber Bragg Grating Sensors • Sensor Interrogation Systems • Applications and Field Studies This presentation will focus on key technology components in a Fiber Bragg Grating (FBG) sensing system, including sensor design and construction, interrogation techniques, system integration, and data processing. Fiber Bragg Grating (FBG) sensing systems have emerged to be a practical technology for strain sensing, and are now deployed in a wide variety of applications including health monitoring of civil structures (highways, bridges, buildings, and dams), long-term fatigue assessment in ship hulls, and oil well pressure/temperature monitoring. Moreover, myriad potential applications are under active development, such as smart structures for aerospace vehicles, remote monitoring applications in nuclear plants, power cables, pipelines, and tow-arrays, as well as bio-medical and chemical sensing for trace pollutants, toxic gases, and in vivo temperature profiling in human bodies. FBG sensors are superior in their signal processing simplicity as the information is directly obtained by detecting Bragg wavelength shifts induced by the measurands. The FBG wavelength shift is directly proportional to the induced strain, temperature variation, or refractive index profile. For mechanical sensing, strain and temperature are the typical direct measurands. For sensing electromagnetic fields or bio-chemical agents, the FBGs would be integrated with appropriate materials to tranfer sensing parameters to temperature, strain, or refractive index changes.