where a is the outer diameter of a fiber, f ( r ) is the initial shape of the dopant distribution, J0 and J1 are Bessel functions of the first kind with orders of zero and one, respectively, n
where a is the outer diameter of a fiber, f ( r ) is the initialshape of the dopant distribution, J0 and J1 are Bessel functions ofthe first kind with orders of zero and one, respectively, n