Abstract
Measurement results of bending diameter dependence of the crosstalk of each core in a multi-core fiber are presented. The crosstalk of cores shows different diameter dependence although the difference in core parameters is very small. The behavior is explained by taking into account the change of propagation constant caused by the fluctuation in the diameter and the refractive index of cores. The diameter dependence simulated with coupled-power theory shows the same tendency with the measured crosstalk.