The possibility of applying a method based on ray optics and modal relations to elliptical graded-index fibers is discussed, and the limits of validity are indicated. Two distinct classes of rays (whispering and bouncing) may be defined, along with a tunneling-radiating effect which both classes of rays may undergo. It turns out that, in the assumed reference system, the evaluation of the modal constants becomes less accurate when the index profile departs from a nearly step shape, especially for high ellipticities. However, when small ellipticities are considered (which correspond to practical cases), it is possible to evaluate the intermodal dispersion with sufficient accuracy.
© 1980 Optical Society of AmericaPDF Article