Fig. 1. Schematic of the femtosecond-grating preparation process

Fig. 2. FBG reflection and transmission spectra

Fig. 3. Schematic of the experimental setup

Fig. 4. Annealing process

Fig. 5. FBG spectra before and after annealing

Fig. 6. Schematic of package structure

Fig. 7. Photo of the sensor

Fig. 8. Temperature calibration experiment system

Fig. 9. Calibration process record

Fig. 10. Fitted result of center wavelength as a function of temperature

Fig. 11. Temperature measurement error distribution

Fig. 12. Sensor actual measurement installation diagram

Fig. 13. System operation interface