Analysis on strain and temperature sensing characteristic of sampled fiber grating

摘要

Sampled fiber Bragg grating(SFBG) has caused extensive research interest due to its special filtering characteristic, strict wavelength interval, compact structure, easy integration and low cost etc. Based on coupling-mode theory, the reflective spectrum of sampled fiber Bragg grating was analyzed using transmission matrix method. Strain and temperature sensing characteristics of sampled fiber Bragg grating were discussed in the paper. Wavelength shift and transmission intensity vary linearly with strain and temperature. The change of strain and temperature can be determined simultaneously by a single sampled fiber grating. In the experiment, the strain and temperature of sampled fiber Bragg grating change simultaneously, the photoelastic coefficients of sampled fiber Bragg grating were P_(11)=0.121, P_(12)=0.27. The Poisson ratio of optical fiber core stuff was 0.17, the thermal expansion coefficient was 5.5×l0~(-7)/°C , and the calorescence coefficient of optical fiber was 8.3×10~(-6)/°C. We can get that A, B, C and D were separately -0.00055nm/ε , 0.013nm/°C, -0.00033/ε , -0.00011/°C by calculating. Strain measurement ranged from 0 με to 2500 με. Temperature measurement ranged from 0°C to 300°C.