This review provides a comprehensive overview of FBG sensor technology, focusing on their operating principles, key advantages such as high sensitivity and immunity to electromagnetic interference, and common challenges like temperature-strain cross-sensitivity and the high. This review provides a comprehensive overview of FBG sensor technology, focusing on their operating principles, key advantages such as high sensitivity and immunity to electromagnetic interference, and common challenges like temperature-strain cross-sensitivity and the high. Fiber Bragg grating (FBG) sensors have emerged as advanced tools for monitoring a wide range of physical parameters in various fields, including structural health, aerospace, biochemical, and environmental applications. These features make high-temperature fiber Bragg gratings (FBGs) suitable for the most complex sensing applications such as turbines, aerospaces, gas and oil explorations. Abstract—Various types of high temperature fibre Bragg gratings (FBGs) for sensing applications, are briefly reviewed, discussing their various figures of merit and performance. References are provided to currently available commercial grade high temperature FBG sensors. Keywords—Fibre Bragg. A fiber Bragg grating is a periodic or aperiodic perturbation of the effective refractive index in the core of an optical fiber (see Figure 1). Typically, the perturbation is approximately periodic over a certain length of e. Roehrl, "Sensing in Extreme High Temperature Environments with Regenerated Fiber Bragg Gratings," in Advanced Photonics Congress 2024, Technical Digest Series.