The attenuation of rays propagating at nearly grazing incidence within lossless dielectric circles and spheres is given. There are no trapped rays, no matter how great the refractive index of the structure; however, many rays are only very weakly attenuated. These are the ‘leaky rays’ that are predicted, incorrectly, by Fresnel's laws to be trapped.
No takes yet. Share an insight, caveat, or question.
Snyder et al. (1974) studied this question.