Radiation loss and mode field distribution in curved holey fibers

We present a method for computing the distortion of the mode field distribution and analyze the radiation loss arising in curved holey fibers with different ratio of air hole dimension to holes separation d/Λ. The analysis shows that the fields of holey fibers with d/Λ>0.35 are strongly concentrated inside the fiber and such holey fibers almost are not exposed by the bend loss. The fields of the holey fibers with d/Λ<0.35 spread wider until the fiber ends. Therefore, they expose substantial radiation loss on their bend. At that, the loss strongly depends on the number of holey fiber lattice periods, bend radius and wavelength of guided radiation.