Sagnac interferometer based on low-birefringence photonic crystal fiber for strain measurement

An optical fiber strain sensor by using low-birefringence photonic crystal fiber (PCF) based Sagnac loop is demonstrated. A fiber Sagnac loop is formed by the low-birefringence PCF of about 40cm, and a section of about 140mm PCF is used as the strain sensing element. The output spectra of Sagnac loop under different strain levels are measured and analyzed. The sensitivity of the strain measurement of -0.457pm/με is achieved within the range of 0-2520με.