Fig. 1. Experimental equipment of fiber Bragg grating temperature sensor

Fig. 2. Variation of temperature with time measured by silicon diode reference thermometer

Fig. 3. Temperature response curves of bare grating and ORMOCER coated grating

Fig. 4. Comparison of characteristic curves of wavelength variation of two FBGs with temperature during heating process（The insert shows a linear fitting curve of wavelength and temperature of bare grating and OMOCER coating grating in the range 210-293 K）