Relationship between nonlinear effective core area and backscattering capture fraction for singlemode optical fibres

An exact relationship between the effective core area A_eff and the backscattering capture fraction B, which holds for fibres of arbitrary refractive index profiles, is given. It is shown that the same quantity that describes the dependency of B from the mode field diameter 2w_D, the so called correction factor, can also be used for the relationship between A_eff and 2w_D and vice versa