mode field diameter), is above 1.20 for photonic crystal fibers (PCFs) with structural
parameters in the range of d/Λ≅ 0.40 to 0.90 (d/Λ ratio of hole diameter d and pitch Λ). By
using the far-field scanning (FFS) technique and the finite difference method, the results of
experimental measurements and numerical simulations differed by only 0.9 to 3.0% for two
types of PCFs. The finding that kn≠ 1.0 for PCFs indicates that their electrical field …