This example demonstrates a temperature sensor based on fiber Bragg gratings (FBG). The temperature-dependent change of the refractive indices of the fiber, consequently the shift of its Bragg wavelength, is used as a measure of the temperature. Understand the simulation workflow and key results. High-temperature-resistant fiber Bragg gratings (FBGs) are the main competitors to thermocouples as sensors in applications for high temperature environments defined as being in the 600–1200 °C temperature range. Consequently, reflected light wavelength shifts and temperature.