Curvature sensor based on low-birefringence photonic crystal fiber Sagnac loop

A fiber optic curvature sensor with low-birefringence photonic crystal fiber (PCF) based Sagnac loop is demonstrated experimentally. The low-birefringence PCF is about 40cm long, using as the sensing element. The Sagnac output spectra under different curvatures are measured and analyzed. When the curvature is varied from 0 to 9.9m^-1, the total wavelength shift is about 3.3nm, and it has a linear relationship with the curvature. The curvature sensitivity of about -0.337nm/m^-1 is achieved.