Fig. 1. Schematic of the experimental setup for the high-temperature fiber laser sensing system.

Fig. 2. Reflectance spectrum and transmittance spectrum of the seed grating for thermal regeneration.

Fig. 3. Evolution of the refractive index modulation during the regeneration experiment.

Fig. 4. ASE output spectrum and the fiber laser output spectrum before the thermal generation.

Fig. 5. Lasing wavelength evolution at different high temperatures.

Fig. 6. Thermal wavelength shift of the fiber laser output and its linear fitting curves during the cooling and heating process.

Fig. 7. Reflectance spectrum of the RFBG and its laser spectrum after the regeneration.

Fig. 8. Wavelength evolution and power stability of the fiber laser at 700°C.