ABSTRACT
This chapter discusses the mechanisms that used to sense fiber Bragg gratings after reviewing the modeling simulation methods. The incident light on a Bragg grating with a grating period and effective refractive index mode will be reflected back at the wavelength typically named Bragg wavelength. The Bragg wavelength is affected significantly by the change of the ambient temperature, applied strain, and incident wavelength. A shift in Bragg wavelength due to the change in temperature can be done in two ways. The First, due to the thermal expansion/contraction, this leads to change the grating period and thus changes the Bragg wavelength. The second is due to the effective refractive index mode of the fiber, which is temperature dependent, and also affects the Bragg wavelength value. The sensitivity of the fiber Bragg grating due to the temperature and strain variation has been investigated by comparison between silica and polymer optical fibers.
