Numerical investigation of the effects of active length and GeO2 doping concentration on the thermal sensitivity of fiber Bragg grating sensors

In this work, the thermo-optic coefficient is studied in the temperature range between 100 and 800 °C by utilizing fiber Bragg grating technology. The thermo-optical coefficient was found to rise with temperature. Simulation is used for several related parameters. Reflected wavelengths were created by applying coefficients of thermal expansion, thermo-optical coefficients, and induced temperature ranges. The wavelength of light reflected from a specific light source spectrum is determined by the temperature-induced changes in the grating period and refractive index. The effect of sensor length is also studied by the application of specific lengths. A sensor length value of 15 mm represents the length that achieves the ideal balance (optimal balance) between high sensitivity and spectral stability. At this length, the sensitivity is 14.8 pm/°C, a very strong value and very close to the peak, but with greater stability in the waveform.