ABSTRACT
This chapter details the history of fiber Bragg granting, measurement of different physical parameters like temperature, strain, and refractive index, and different methods to discriminate strain and temperature sensed by the fiber Bragg grating (FBG). It discusses several physical parameters like pressure, force, displacement, vibration, liquid level, and magnetic field can be measured indirectly using strain sensing of the FBG. The chapter desctribes working principle of the FBG as sensors. The FBG sensors are one of the most exciting developments in the field of optical fiber sensing. The Bragg wavelength of FBG sensor strongly depends on applied strain to the FBG and local temperature surrounding it. The thermal-induced changes in Bragg wavelength are due to two major contributions: the first due to the change in effective refractive index of the guided mode and the second owing to the change in the grating period.
