Bent induced refractive index profile variation and mode field distribution of step-index multimode optical fiber

The effect of bending of step-index optical fiber on its refractive index profile and the mode field
distribution were investigated. An enhanced slab model is suggested in this investigation. A qualitative
study has been done on a bent step-index optical fiber. A very small radius of bending curvature (R) has
been reached, practically R is 9.25 mm. In this case a dramatic change of the refractive index profile has
been observed with an induced birefringence. The refractive index profile is recovered from the
interferograms which were generated by Mach–Zehnder interferometer. The interferogram has been
analyzed using advanced image analyses software. We have proposed another approach to calculate the
refractive index profile of bent optical fiber. In this approach the fiber is divided into layers and slabs,
simultaneously. The induced refractive index profile variation of the bent optical fiber, for parallel and
perpendicular components of the light beam, is calculated considering the refraction of the light beam
traversing the fiber. The mode field distribution and mode numbers in these two directions of
polarizations are determined for both straight and bent fibers.