Radiation loss in curved holey fibres

We analyse the distortion of the mode field distribution and radiation losses arising in curved holey fibres with different guidance mechanisms. The analysis shows that the fields of holey fibres with band gap guidance are strongly concentrated inside of the fibre and such holey fibres almost are not exposed by the bend loss. The fields of the holey fibres with effective index difference guiding spread wider until the fibre ends. Therefore, they expose substantial radiation loss on their bend. At that, these losses strongly depend on the number of holey fibre lattice periods, air hole diameter and hole separation.