Fig. 1. Coating structure of single grating temperature and humidity sensor

Fig. 2. Physical image of the photoelectric microscope

Fig. 3. Semi-coated grating and coating effect

Fig. 4. Principle of the experimental test platform

Fig. 5. Reflectance spectra of the FBG at different temperatures

Fig. 6. Gaussian fitted curve of uncoated grating peak

Fig. 7. Variation curve of temperature with wavelength

Fig. 8. Calculation of spectral area

Fig. 9. Relationship between curve area and temperature

Fig. 10. Reflectance spectra of grating under different humidity

Fig. 11. Function curve of spectral area and relative humidity

Fig. 12. Repeatability test of the humidity

Fig. 13. Variation curve of humidity response with time