Research on the elastic-optical coefficient of fiber-optic and the experimental measurement by fiber Bragg grating

The strain characteristics of fiber-optic refractive index (RI) is theoretically investigated, combined with practical application situations, including a systematic theoretical model to explain its physical nature and analyze its functional mechanism. The simplified analytical expression of elastic-optical coefficient is obtained, which is more direct than the existing ones. Besides, the change in RI of fiber-optic with strain is measured by a succinct method based on fiber Bragg grating (FBG) that is simple in structure and easy to operate. We got the conclusion that the variation of RI is negative linearly proportional to strain when optical fiber is stretched from the experimental results. As a result, the theoretical and experimental reduction rate of 0.45 × 10−6/μe and 0.44 × 10−6/μe, respectively. The elastic-optical coefficient of fiber-optic is measured and the measurement results agree well with the previous theoretical analysis. Furthermore, our work shows major application potential in fiber-optic strain sensor systems.