Structure and propagation of modes of large mode area holey fibers.

We report cross-section measurement and propagation measurement of modes of large mode area holey fibers using near-field scanning optical microscopy (NSOM). Mode profiles are measured at the fiber end face using a scanning optical fiber tip held 10 nm from the surface, and compared to theoretical models. Both amplitude and phase of the electric field of the propagating light is measured using NSOM techniques as a function of distance from the fiber end, from 10 nm to 150 microm. Good agreement is found between the data and simple scalar paraxial beam propagation simulations of theoretical mode profiles.