A study of bending effect on the femtosecond-pulse inscribed fiber Bragg gratings in a dual-core fiber

Fiber Bragg gratings with different reflection wavelengths have been inscribed in different cores of a dual-core fiber section. The effect of fiber bending on the FBG reflection spectra has been studied. Various interrogation schemes are presented, including a single-end scheme based on a cross-talk between the cores that uses only standard optical components. Simultaneous interrogation of the FBGs in both cores allows to achieve a bending sensitivity of 12.8 pm/m−1, being free of temperature and strain influence. The technology enables the development of real-time bending sensors with high spatial resolution based on series of FBGs with different wavelength inscribed along the multi-core fiber.