Following are the drawbacks or disadvantages of a Fiber Bragg Grating (FBG) Sensor: It is thermally sensitive. It is difficult to demodulate wavelength shift. Fiber optic sensors work by modulating one or more properties of the light wave, such as intensity, phase, polarization, and frequency. This microscopic structure. A fiber Bragg grating (FBG) is a type of distributed Bragg reflector constructed in a short segment of optical fiber that reflects particular wavelengths of light and transmits all others. This review provides a comprehensive overview of FBG sensor technology.