While I can understand the longitudinal component from the point of view of reflections in cavity (example of the Zenneck wave), however, the main crux of this idea is that it still needs a medium for the reflections to occur.
In this paper which i cited, they created it in vacuum, or termed...
In Edward Collet's book "Polarized Light: Fundamentals and Applications", Chapter 3 states that:
However, in recent years (as recent as 2008), I came across a paper published in Nature Photonics that a group of scientists, Haifeng Wang et al. from Data Storage Institute based in Singapore...