Comparative analysis of classical and special single-mode microstructured optical fibers as a sensing element for fiber optic microbend sensors

The influence of microbends on a phase shift and attenuation in a classical Corning SMF-28 fiber and in a special microstructured single-mode fiber with a limited number of air-hole rings in the cladding has been investigated. The largest measured phase shift of 750 deg/mm was obtained for the classical fiber at displacement mag- nitude of 117 m. This corresponds to 1.310 �3 change in the effective refractive index of the fundamental LP01 mode in a microbent optical fiber section with length of 24 mm. The phase shift for the investigated microstructured fibers is in 3.9 times less. The cutoff of radiation intensity takes place at displacement magnitudes of 55 and 270 m for the mi- crostructured fiber and for the SMF-28 fiber, respectively. It is shown that the sensitivity of the microstructured fiber to the displacement magnitude is in about five times higher than that of the Corning SMF-28 fiber. © 2009